Laser welding apparatus and method for high nitrogen stainless steel

Abstract

The application relates to the technical field of welding, and discloses a laser welding device and method for high-nitrogen stainless steel. The device comprises a cabin, a laser and a laser welding head connected to the cabin, a vacuum gas charging system, a side blowing system, a magnetic field generator, a power supply and a sliding rheostat. A moving platform is arranged in the cabin. The laser and the laser welding head are used for emitting a laser beam to a workpiece. The vacuum gas charging system is used for discharging air in the cabin and charging nitrogen into the cabin. The magnetic field generator is used for forming a magnetic field in the cabin. The laser welding head, the power supply, the sliding rheostat and the moving platform can form an electric field in the cabin. In the process of laser welding the workpiece, the side blowing nozzle and the magnetic field and the electric field formed in the cabin cooperate to reduce the plasma density floating on the surface of the workpiece, improve the welding energy, enhance the coupling efficiency of the laser beam and the workpiece, and further improve the welding seam depth and quality.

Description

Technical Field

[0001] This application belongs to the field of welding technology, specifically relating to a laser welding apparatus and method for high-nitrogen stainless steel. Background Technology

[0002] High-nitrogen stainless steel, as a new type of engineering material, incorporates nitrogen, an inexpensive and environmentally friendly alloying element, into stainless steel. The dissolved nitrogen significantly improves the strength, toughness, and corrosion resistance of stainless steel and can partially or completely replace expensive nickel, thus reducing costs. Therefore, it is widely used in aerospace, petrochemical, power industry, marine engineering, transportation, and other fields.

[0003] Because the nitrogen content in high-nitrogen stainless steel exceeds its solubility under normal pressure, nitrogen escape and nitrogen porosity will occur during fusion welding, reducing the nitrogen content in the weld and causing deterioration of the weld joint's performance. Increasing the nitrogen partial pressure can suppress nitrogen escape, avoid defects such as porosity and microporousness, and thus improve the quality of the welded parts. Therefore, welding under pressurized nitrogen atmosphere is one way to solve the problem of nitrogen loss and performance deterioration in high-nitrogen stainless steel fusion weld joints.

[0004] Currently, commonly used welding methods include gas inert gas welding (MIG), gas metal arc welding (GMAW), and laser welding. Among these, MIG and GMAW, as arc welding methods, have a large heat-affected zone, which can easily lead to problems such as coarse grains and thermal deformation of the weld area. In contrast, laser welding offers high precision, low heat input, and a large aspect ratio, resulting in a smaller heat-affected zone, less workpiece deformation, excellent surface quality, high weld strength, and ease of automation. Therefore, it has become a replacement technology for some traditional welding methods.

[0005] However, during the laser welding of high-nitrogen stainless steel, metal vapor ionizes at high temperatures to generate dense plasma plumes that are difficult to predict and control. These plasmas float on the metal surface and absorb, scatter, and reflect the energy of the high-energy laser beam, significantly reducing the welding energy and decreasing the coupling efficiency between the laser beam and the metal, resulting in a decrease in weld depth and quality. Summary of the Invention

[0006] This application aims to address at least one of the technical problems existing in the related art.

[0007] Therefore, the first aspect of this application provides a laser welding apparatus for high-nitrogen stainless steel.

[0008] The second aspect of this application provides a laser welding method for high-nitrogen stainless steel.

[0009] In view of the above, according to a first aspect of the embodiments of this application, a laser welding apparatus for high-nitrogen stainless steel is provided, comprising: a chamber, wherein a movable platform is disposed within the chamber, and a workpiece is placed on the movable platform; a laser and a laser welding head connected to each other, disposed outside the chamber, for emitting a laser beam toward the workpiece; a vacuum filling system, connected to the chamber, for discharging air from the chamber and filling the chamber with nitrogen, providing a pressurized nitrogen environment for laser welding of the workpiece; a side-blowing system, including side-blowing nozzles disposed within the chamber; and a magnetic field generator, disposed within the chamber, for... A magnetic field is formed inside the chamber; a power supply, the positive terminal of which is electrically connected to the laser welding head; a sliding rheostat, one end of which is electrically connected to the negative terminal of the power supply, and the other end of which is electrically connected to the moving platform; wherein, the laser welding head, the power supply, the sliding rheostat, and the moving platform as a whole can form an electric field inside the chamber; wherein, during the laser welding of the workpiece, the side-blowing nozzle blows auxiliary gas onto the workpiece to disperse at least a portion of the plasma generated during the laser welding process; the magnetic field and electric field formed inside the chamber work together to accelerate and deflect at least a portion of the plasma floating on the surface of the workpiece.

[0010] In one possible implementation, the angle between the blowing direction of the side-blowing nozzle and the surface of the workpiece is 30° to 50°; and / or, the distance between the blowing port of the side-blowing nozzle and the surface of the workpiece is 12 mm to 18 mm; and / or, the blowing flow rate of the side-blowing system is 40 L / min to 60 L / min.

[0011] In one possible implementation, the laser welding apparatus further includes: a transmission window disposed on the bulkhead of the cabin; a laser beam emitted by the laser welding head passes through the transmission window to the welding area of ​​the workpiece.

[0012] In one possible implementation, the laser welding apparatus further includes: a purification tube with its inlet facing the workpiece; a fan disposed inside the purification tube for drawing in fumes generated during the welding process; and a filter assembly disposed inside the purification tube and located on the outlet side of the fan, the filter assembly including a first filter, a second filter, and a third filter arranged sequentially along the gas flow direction inside the purification tube; wherein the fumes, after being filtered by the filter assembly, flow out from the purification tube into the chamber.

[0013] In one possible implementation, the laser welding apparatus further includes a wire feeding device disposed within the chamber for feeding welding wire during the laser welding process.

[0014] In one possible implementation, the vacuum filling system includes: a vacuum system comprising a mechanical pump and a Roots pump, the inlet of the Roots pump being connected to the chamber, and the outlet of the Roots pump being connected to the inlet of the mechanical pump, the vacuum system being used to vent air from the chamber; and a filling system, connected to the chamber, for filling the chamber with nitrogen.

[0015] According to a second aspect of the embodiments of this application, a laser welding method for high-nitrogen stainless steel is proposed, comprising the following steps: in response to a welding request, acquiring operating parameters of a laser welding apparatus, the operating parameters including a target operating pressure inside the chamber, a target gas flow rate of a side-blowing system, an operating current of a magnetic field generator, an operating resistance of a sliding rheostat, and a laser power of a laser; controlling the operation of a vacuum filling system according to the target operating pressure to expel air from the chamber and fill the chamber with nitrogen, so that the pressure inside the chamber reaches the target operating pressure; controlling the operation of the side-blowing system according to the target gas flow rate to blow auxiliary gas onto the workpiece at the target gas flow rate; controlling the magnetic field generator to operate at the operating current according to the operating current to form a magnetic field inside the chamber; controlling the sliding rheostat to operate at the operating resistance according to the operating resistance to form an electric field inside the chamber; and controlling the operation of the laser according to the laser power to emit a laser beam toward the workpiece and perform laser welding on the welding area of ​​the workpiece.

[0016] In one possible implementation, the operating parameters also include the moving speed of the moving platform. While controlling the operation of the laser based on the laser power, the laser welding method further includes: controlling the moving platform to move at the moving speed to move the workpiece.

[0017] In one possible implementation, the operating parameters further include the wire feeding speed of the wire feeding device. While controlling the operation of the laser according to the laser power, the laser welding method further includes: controlling the operation of the wire feeding device according to the wire feeding speed, and feeding welding wire to the welding area of ​​the workpiece at the wire feeding speed.

[0018] In one possible implementation, the workpiece is made of high-nitrogen stainless steel, the chemical composition of which includes N, C, Si, Ni, Mn, Mo, V, and Cr, and the target working pressure is calculated according to the following formula:

[0019]

[0020] in,

[0021]

[0022]

[0023] In the formula, Work pressure to achieve goals To balance the calculated pressure under nitrogen solubility, The pressure is standard atmosphere, and k is an empirical coefficient. T [%N] represents the temperature of the molten pool formed by the laser beam acting on the workpiece; [%N] represents the mass percentage of nitrogen (N) in the high-nitrogen stainless steel; [%C] represents the mass percentage of carbon (C) in the high-nitrogen stainless steel; [%Si] represents the mass percentage of silicon (Si) in the high-nitrogen stainless steel; [%Ni] represents the mass percentage of nitrogen (Ni) in the high-nitrogen stainless steel; [%Mn] represents the mass percentage of mn (Mn) in the high-nitrogen stainless steel; [%Mo] represents the mass percentage of molybdenum (Mo) in the high-nitrogen stainless steel; [%V] represents the mass percentage of v (V) in the high-nitrogen stainless steel; and [%Cr] represents the mass percentage of chromium (Cr) in the high-nitrogen stainless steel. denoted as the coefficient of influence of the target working pressure on nitrogen activity, and H is the correction coefficient for nitrogen solubility.

[0024] The laser welding apparatus and method for high-nitrogen stainless steel provided in this application can achieve at least the following technical effects:

[0025] In this application, a chamber provides a working space for laser welding of high-nitrogen stainless steel workpieces. A moving platform can move relative to the chamber to move the workpiece relative to the chamber. A vacuum filling system expels air from the chamber and fills it with nitrogen, providing a pressurized nitrogen environment for laser welding to improve welding quality. The laser and laser welding head are located outside the chamber, i.e., outside the pressurized environment, protecting the laser and laser welding head to facilitate pressurized laser welding. The laser and laser welding head emit laser beams towards the welding area of ​​the workpiece to achieve welding. A side-blowing system includes side-blowing nozzles located inside the chamber, blowing auxiliary gas onto the workpiece to disperse at least a portion of the plasma generated during welding. A magnetic field generator is located inside the chamber to create a magnetic field inside the chamber, causing at least a portion of the plasma to deflect. The laser welding head, power supply, sliding rheostat, and moving platform together create an electric field inside the chamber to increase the movement speed of at least a portion of the charged plasma. In this application, the side-blowing system, along with the magnetic and electric fields formed within the chamber, work together to guide at least a portion of the plasma generated during laser welding away from the workpiece surface, reducing the plasma density on the weld surface, increasing welding energy, enhancing the coupling efficiency between the laser beam and the workpiece, and thus improving the weld depth and quality.

[0026] The above general description and the description below are exemplary and illustrative only and are not intended to limit this application. Attached Figure Description

[0027] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations and drawings do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are shown as similar elements. The drawings are not to be scaled. And wherein:

[0028] Figure 1 This is a schematic diagram of the structure of the laser welding apparatus provided in the embodiments of this disclosure;

[0029] Figure 2 for Figure 1 Enlarged view of point F in the middle;

[0030] Figure 3 A flowchart illustrating a welding method provided in one embodiment of this disclosure;

[0031] Figure 4 A flowchart of a welding method provided in another embodiment of this disclosure;

[0032] Figure 5 This is a schematic diagram of the controller provided in an embodiment of the present disclosure.

[0033] The reference numerals in the attached figures are as follows:

[0034] 100: Laser welding device; 101: Cabin; 102: Cabin body; 103: Pressure-resistant door; 104: Sealing ring; 105: Vacuum filling system; 106: Mechanical pump; 107: Roots pump; 108: Connecting pipeline; 109: Laser system; 110: Laser welding head; 111: Laser; 112: Side-blowing nozzle; 113: Air outlet; 114: Moving platform; 115: Power supply; 116: Sliding rheostat; 117: Transmission window; 118: Purification pipe; 119: Fan; 120: Filter assembly; 121: First filter; 122: Second filter; 123: Third filter; 124: Wire feeding device;

[0035] 200: Workpiece;

[0036] 800: Controller; 802: Processor; 804: Memory; 806: Communication interface; 808: Bus. Detailed Implementation

[0037] To provide a more detailed understanding of the features and technical content of the embodiments of this disclosure, the implementation of the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this disclosure. In the following technical description, for ease of explanation, several details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be simplified in their depiction to simplify the drawings.

[0038] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0039] In this disclosure, the terms "upper," "lower," "inner," "middle," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for better description of the embodiments of this disclosure and their implementations, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to require them to be constructed and operated in a specific orientation. Furthermore, some of the aforementioned terms may be used to indicate other meanings besides orientation or positional relationship; for example, the term "upper" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in the embodiments of this disclosure according to the specific circumstances.

[0040] Furthermore, the terms "set up," "connect," and "fix" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this disclosure according to the specific circumstances.

[0041] Unless otherwise stated, the term "multiple" means two or more.

[0042] The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0043] It should be noted that, unless otherwise specified, the embodiments and features described in the present disclosure can be combined with each other.

[0044] Combination Figure 1 and Figure 2As shown, according to a first aspect of the embodiments of this application, a laser welding apparatus 100 for high-nitrogen stainless steel is proposed, including a chamber 101, a laser 111 and a laser welding head 110 connected to each other, a vacuum filling system 105, a side-blowing system, a magnetic field generator, a power supply 115, and a sliding rheostat 116. A moving platform 114 is provided inside the chamber 101, and a workpiece 200 is placed on the moving platform 114. The laser 111 and the laser welding head 110 are located outside the chamber 101 and are used to emit laser beams towards the workpiece 200. The vacuum filling system 105 is connected to the chamber 101 and is used to exhaust the air inside the chamber 101 and fill the chamber 101 with nitrogen, providing a pressurized nitrogen environment for laser welding the workpiece 200. The side-blowing system includes a side-blowing nozzle 112 disposed inside the chamber 101. The magnetic field generator is disposed in the chamber 101 and is used to generate a magnetic field inside the chamber 101. The positive terminal of power supply 115 is electrically connected to laser welding head 110. One end of sliding rheostat 116 is electrically connected to the negative terminal of power supply 115, and the other end of sliding rheostat 116 is electrically connected to moving platform 114. The laser welding head 110, power supply 115, sliding rheostat 116, and moving platform 114 together can form an electric field inside the chamber 101. During laser welding of workpiece 200, side-blowing nozzle 112 blows auxiliary gas onto workpiece 200 to disperse at least a portion of the plasma generated during laser welding. The magnetic and electric fields formed within chamber 101 work together to accelerate and deflect at least a portion of the plasma floating on the surface of workpiece 200.

[0045] The chamber 101 provides a working space for laser welding of high-nitrogen stainless steel workpiece 200. A movable platform 114 is movably disposed inside the chamber 101. The movement of the movable platform 114 relative to the chamber 101 moves the workpiece 200 relative to the chamber 101, thereby performing welding on the welding area of ​​the workpiece 200. The specific structure of the movable platform 114 is not limited. For example, a trolley can be used. Alternatively, a slide rail can be installed inside the chamber 101, with the movable platform 114 slidably mounted on the slide rail. A motor is connected to the movable platform 114, driving the movable platform 114 to move relative to the chamber 101.

[0046] The vacuum filling system 105 is connected to the chamber 101. The vacuum filling system 105 expels air from the chamber 101 and fills it with nitrogen, providing a pressurized nitrogen environment for laser welding to improve welding quality. Specifically, the laser welding process is carried out in a pure high-pressure nitrogen environment. Pressurization significantly increases the saturated solubility of nitrogen in the molten steel. During the fusion welding process to form the weld, it reduces nitrogen escape from the weld and the formation of nitrogen pores, resulting in a weld with high nitrogen content and excellent quality.

[0047] The laser 111 and the laser welding head 110 are located outside the chamber 101, that is, the laser 111 and the laser welding head 110 are located outside the pressurized environment to protect the laser 111 and the laser welding head 110 so as to successfully realize pressurized laser welding. The laser 111 and the laser welding head 110 are used to emit laser beams to the welding area of ​​the workpiece 200 to realize welding of the workpiece 200.

[0048] The side-blowing system includes a side-blowing nozzle 112 disposed within the chamber 101. The nozzle 112's air outlet 113 is oriented towards the workpiece 200 to blow auxiliary gas onto the workpiece 200, dispersing at least a portion of the plasma generated during laser welding and reducing the plasma density floating on the surface of the workpiece 200. The auxiliary gas can be nitrogen. Other structures of the side-blowing system are not limited, as long as they can provide nitrogen to the side-blowing nozzle 112 and allow nitrogen to be ejected from the nozzle 112.

[0049] A magnetic field generator is installed in the chamber 101 to generate a magnetic field inside the chamber 101, thereby deflecting at least a portion of the plasma. The magnetic field generator may be an electromagnetic coil, which may be located inside the moving platform 114. Figure 1 The Y in the figure indicates the direction of the magnetic field, which is perpendicular to the plane of the paper and inwards. That is, the electromagnetic coil can generate a magnetic field inside the housing 101, distributed above the workpiece 200, with the direction of the magnetic field perpendicular to the plane of the paper and inwards. During laser welding, the workpiece 200 moves along... Figure 1 When the magnetic field moves left or right, it causes at least a portion of the plasma to shift. In practical applications, the magnetic flux density of the magnetic field can be controlled by adjusting the current in the electromagnetic coil.

[0050] The positive terminal of power supply 115 is electrically connected to laser welding head 110, one end of sliding rheostat 116 is electrically connected to the negative terminal of power supply 115, and the other end of sliding rheostat 116 is electrically connected to moving platform 114. This allows the laser welding head 110, power supply 115, sliding rheostat 116, and moving platform 114 to form an electric field inside cabin 101, thereby increasing the movement speed of at least a portion of the charged plasma. In practical applications, the magnitude of the electric field formed by power supply 115 can be controlled by changing the resistance value of sliding rheostat 116.

[0051] During the laser welding of workpiece 200, the side-blowing nozzle 112 blows auxiliary gas onto workpiece 200 to disperse at least part of the plasma generated during laser welding. Combined with the synergistic effect of the magnetic and electric fields formed within the chamber 101, at least part of the plasma floating on the surface of workpiece 200 is accelerated and deflected, thereby controlling the morphology and spatial distribution of the plasma, reducing the absorption, scattering, and reflection of laser energy by the plasma, reducing the loss of the high-energy laser beam, increasing the coupling efficiency between the laser beam and workpiece 200, and improving welding efficiency and quality.

[0052] In this embodiment, the side-blowing system and the magnetic and electric fields formed in the chamber 101 work together to guide at least part of the plasma generated during the laser welding process away from the surface of the workpiece 200, reduce the plasma density on the weld surface, increase the welding energy, enhance the coupling efficiency between the laser beam and the workpiece 200, and thus improve the weld depth and quality.

[0053] Specifically, the interaction between the high-energy laser beam, workpiece 200, and shielding gas (nitrogen) generates a dense plasma. This plasma shields some of the laser's energy, affecting the welding quality. The plasma consists of electrons, ions, and neutral atoms. During laser deep-penetration welding, after the plasma is generated, it diffuses outwards due to the concentration difference between charged particles and their surroundings. The diffusion rate is related to its average thermal velocity and concentration gradient. Because the mass of an electron is much smaller than that of a positive ion, the average thermal velocity of electrons is much higher than that of positive ions. That is, the diffusion rate of electrons is much higher than that of positive ions. This causes positive ions to accumulate above the workpiece 200, while electrons are distributed near the walls of the chamber 101, forming an electric field from the workpiece 200 to the chamber walls. If an external load is applied, a small amount of plasma current will be generated. In this embodiment, the side-blowing nozzle 112 blows auxiliary gas onto the workpiece 200 to disperse at least some of the plasma generated during the laser welding process. The magnetic field generator can generate a magnetic field inside the chamber 101. Moving charged particles in the magnetic field are deflected by electromagnetic forces, causing at least a portion of the plasma to shift away from the workpiece 200, thus reducing the plasma density floating on the surface of the workpiece 200. The laser welding head 110, power supply 115, sliding rheostat 116, and moving platform 114 together can generate an electric field inside the chamber 101. The applied positive electric field increases the moving speed of the charged particles, thereby increasing the degree of deflection. Through the synergistic effect of the side-blowing system and the magnetic and electric fields formed within the chamber 101, the distribution and movement of charged particles in the plasma can be altered, guiding at least a portion of the plasma generated during laser welding away from the surface of the workpiece 200, dispersing at least a portion of the plasma, reducing the plasma density on the weld surface, increasing welding energy, enhancing the coupling efficiency between the laser beam and the workpiece 200, and thus improving the weld depth and quality.

[0054] Combination Figure 1 As shown, in one possible implementation, the cabin 101 includes a cabin body 102, a pressure-resistant door 103, and a sealing ring 104. The pressure-resistant door 103 is closable and mounted on the cabin body 102. The sealing ring 104 is mounted on the cabin body 102. The sealing ring 104 is used to lock the pressure-resistant door 103 to achieve a seal on the cabin 101. The structure of the sealing ring 104 is not limited; it can be used to lock the pressure-resistant door 103 to the cabin body 102. For example, the door can be locked by rotating the teeth of the sealing ring 104. In practical applications, the pressure-resistant door 103 may have pre-drilled terminal holes to provide power to electrical components inside the cabin 101. The pressure-resistant door 103 can also be used to connect to a vacuum inflation system 105.

[0055] In one possible implementation, the cabin 101 can be a horizontal stainless steel furnace shell with a hollow interior.

[0056] In one possible implementation, the hull 101 is provided with multiple viewing holes. The location of the viewing holes is not limited. For example, they can be located at the end of the hull 102 opposite to the pressure-resistant hatch 103.

[0057] For example, the cabin 101 is provided with 6 viewing holes. Among them, 3 viewing holes are used for visual observation. High-speed cameras are installed on the outside of the 3 viewing holes. The high-speed cameras can be used to monitor the welding process, weld morphology and plasma arc generated during laser welding in real time, so as to improve the level of intelligence and automation.

[0058] Combination Figure 1 As shown, in one possible implementation, the laser welding apparatus 100 may include a laser system 109 that can convert electrical energy into a high-energy laser beam. The laser system 109 includes a laser 111 and a laser welding head 110 connected together.

[0059] The specific structure of the laser system 109 and the laser welding head 110 is not limited, as long as they can emit a laser beam to the welding area of ​​the workpiece 200 to weld the workpiece 200. The laser welding head 110 can be an oscillating welding head, a direct fusion welding head, etc.

[0060] Laser 111 can serve as an external source to generate a laser beam. This beam is transmitted via optical fiber to laser welding head 110. Upon receiving the optical signal, laser welding head 110 uses a collimating lens, focusing lens, and protective lens to provide a high-energy laser beam for pressure laser welding of high-nitrogen stainless steel. The laser beam exits from the laser outlet of laser welding head 110, passes through transmission window 117, enters chamber 101, and irradiates workpiece 200 within chamber 101. The energy loss rate along the path is ≤0.5%. Laser 111 can be an all-solid-state design; for example, it can be an all-solid-state laser. The specific structure of the all-solid-state laser 111 is not limited; for example, it can consist of a transmission optical fiber, optical coupler, a complete set of optical components, power supply 115, pump source, and control electronics.

[0061] Laser 111 can be a gas laser, a solid-state laser, a fiber laser, a semiconductor laser, etc. Laser 111 can be equipped with a voltage regulator to achieve power protection.

[0062] In one possible implementation, the laser system 109 also includes a water-cooled heat dissipation structure. The water-cooled heat dissipation structure can be an industrial-grade closed-loop water-cooling system used to circulate heat dissipation for the laser 111 and the laser welding head 110, keeping the temperature of the core components ≤40 ℃.

[0063] In one possible implementation, the laser system 109 may further include a laser collimation and positioning system and a clamping system. Before welding, the position of the workpiece 200 can be fixed by the clamping system, and the welding path can be calibrated by the laser collimation and positioning system with a laser collimation and positioning accuracy ≤0.1 mm, so as to control the workpiece 200 to remain on the same horizontal line during welding.

[0064] In one possible implementation, the monitoring system may further include a camera to monitor the welding process, weld morphology, and plasma arc behavior in real time. The camera may be a charge-coupled device (CCD) camera or a complementary metal-oxide-semiconductor (CMOS) camera. The monitoring system may also include thermocouples, deployed on the moving platform 114, for recording temperature data during the welding process.

[0065] In one possible implementation, the laser welding apparatus 100 may further include a controller 800. Components of the monitoring system, such as cameras, thermocouples, and pressure gauges, can be integrated into the controller 800 via a data bus for monitoring, recording, and automated operation. The controller 800 may also be connected to a screen to display parameters and images.

[0066] In one possible implementation, the laser welding device 100 may also be equipped with an explosion-proof valve and a pressure relief valve. During laser welding, localized overheating can cause a sudden pressure surge. Protection is achieved by controlling the opening of the explosion-proof valve and the pressure relief valve. For example, when the pressure inside the chamber 101 reaches twice the target working pressure, the controller 800 controls the opening of the explosion-proof valve and the pressure relief valve, and can also control the laser welding device 100 to shut down, thus achieving protection.

[0067] In one possible implementation, the laser welding apparatus 100 also includes a monitoring system. The monitoring system includes a pressure gauge that can display the pressure inside the chamber 101 in real time to monitor pressure changes within the chamber 101. For example, it can achieve nitrogen pressure regulation from 0 to 3 MPa. The installation location of the pressure gauge is not limited; for example, it can be installed on the pressure-resistant door 103.

[0068] In practical applications, a clamping structure can be installed on the mobile platform 114 to clamp the workpiece 200 and position it. A weld penetration protection plate can be installed under the mobile platform 114 to prevent weld penetration or damage to the housing 101 during the welding process.

[0069] In practical applications, a lifting structure can be installed below the moving platform 114 to drive the moving platform 114 to move up and down. For example, the lifting structure can be manually adjusted to raise or lower the moving platform 114 by ±3 cm. The moving platform 114 can move back and forth, which can be understood as perpendicular to the vertical and horizontal directions. For example, the moving platform 114 can move back and forth by ±5 cm. By adjusting the position of the moving platform 114, the laser beam emitted by the laser welding head 110 can be focused on the welding area of ​​the workpiece 200.

[0070] Combination Figure 1 and Figure 2 As shown, in some embodiments, the angle between the blowing direction of the side-blowing nozzle 112 and the surface of the workpiece 200 is 30° to 50°. And / or, the distance between the air outlet 113 of the side-blowing nozzle 112 and the surface of the workpiece 200 is 12 mm to 18 mm. And / or, the air flow rate of the side-blowing system is 40 L / min to 60 L / min.

[0071] like Figure 2 As shown, θ is used to indicate the angle between the blowing direction of the side-blowing nozzle 112 and the surface of the workpiece 200. l This is used to illustrate the distance between the air outlet 113 of the side-blowing nozzle 112 and the surface of the workpiece 200.

[0072] The plasma is effectively dispersed by the angle between the blowing direction of the side-blowing nozzle 112 and the surface of the workpiece 200 being 30° to 50° (for example, 45°).

[0073] By using the distance between the air outlet 113 of the side-blowing nozzle 112 and the surface of the workpiece 200, which is 12mm to 18mm (e.g., 15mm), the plasma above the workpiece 200 is dispersed, thereby improving the weld quality.

[0074] The side-blowing system has a blowing flow rate of 40 L / min to 60 L / min, which effectively disperses the plasma during welding and improves the weld quality.

[0075] Combination Figure 1 As shown, in some embodiments, the laser welding apparatus 100 further includes a transmission window 117 disposed on the bulkhead of the housing 101. The laser beam emitted by the laser welding head 110 passes through the transmission window 117 to the welding area of ​​the workpiece 200.

[0076] Specifically, the bulkhead of the cabin 101 has openings, into which double-sided coated pressure-resistant quartz glass is embedded to form a transmission window 117. Through the high-transmittance, high-pressure-resistant, double-sided coated pressure-resistant quartz glass, a laser beam is guided into the interior of the cabin 101 for pressurized laser welding. This achieves the goal of guiding a laser beam into the interior of the cabin 101 while minimizing heat generation and laser reflection.

[0077] Because the laser 111 and the laser welding head 110 have a precise structure and contain a sealed structure, they cannot be placed directly in a pressurized environment. By assembling the laser system 109 on the outside of the cabin 101, the laser beam is introduced into the interior of the cabin 101 through the transmission window 117 for pressurized laser welding, thus ensuring the safety of equipment use.

[0078] Combination Figure 1 and Figure 2 As shown, in some embodiments, the laser welding apparatus 100 further includes a purification pipe 118, a fan 119, and a filter assembly 120. The inlet of the purification pipe 118 faces the workpiece 200. The fan 119 is disposed inside the purification pipe 118 to draw the fumes generated during the welding process into the purification pipe 118. The filter assembly 120 is disposed inside the purification pipe 118 and located on the outlet side of the fan 119. The filter assembly 120 includes a first filter 121, a second filter 122, and a third filter 123 arranged sequentially along the gas flow direction inside the purification pipe 118. The fumes, after being filtered by the filter assembly 120, flow out from the purification pipe 118 into the chamber 101.

[0079] Specifically, the fan 119 is used to draw the fumes generated during welding into the purification pipe 118 and deliver them from the outlet side of the fan 119 to the filter assembly 120. In the filter assembly 120, the first filter 121 is a screen, the second filter 122 is an activated carbon screen, and the third filter 123 is a high-efficiency particulate air (HEPA) filter. The fumes drawn into the purification pipe 118 flow sequentially through the first filter 121, the second filter 122, and the third filter 123, achieving three-stage filtration. This process can absorb over 98% of the welding fumes, achieving efficient absorption and removal of fumes, providing good visibility within the chamber, thus providing a good observation and welding environment, and enabling high-quality welding of high-nitrogen stainless steel.

[0080] In practical applications, a fan can also be used to draw the fumes generated during the welding process into the purification pipe 118.

[0081] Combination Figure 1 and Figure 2 As shown, in some embodiments, the laser welding apparatus 100 further includes a wire feeding device 124. The wire feeding device 124 is disposed inside the chamber 101 and is used to feed the welding wire during the laser welding process.

[0082] The welding wire is fed during the welding process via the wire feeding device 124. The specific structure of the wire feeding device 124 is not limited. The wire feeding speed of the wire feeding device 124 can be from 0.1 m / min to 2 m / min.

[0083] During laser welding, the laser beam emitted by the laser welding head 110 remains focused. The workpiece 200 is moved approximately by controlling the moving platform 114, while the wire feeding device 124 feeds the welding wire to the welding area of ​​the workpiece 200 for welding. The moving speed of the moving platform 114 and the wire feeding speed of the wire feeding device 124 can be adjusted as needed.

[0084] Combination Figure 1 As shown, in some embodiments, the vacuum filling system 105 includes a vacuum system and a filling system. The vacuum system includes a mechanical pump 106 and a Roots pump 107. The inlet of the Roots pump 107 is connected to the chamber 101, and the outlet of the Roots pump 107 is connected to the inlet of the mechanical pump 106. The vacuum system is used to vent air from the chamber 101. The filling system is connected to the chamber 101 and is used to fill the chamber 101 with nitrogen gas.

[0085] Specifically, the inlet of the Roots pump 107 is connected to the chamber 101, and the outlet of the Roots pump 107 is connected to the inlet of the mechanical pump 106, thus connecting the mechanical pump 106 and the Roots pump 107 in series. The Roots pump 107 can be connected to the chamber 101 via the connecting pipe 108. Through the operation of the mechanical pump 106 and the Roots pump 107, air inside the chamber 101 is expelled, providing a vacuum environment for subsequent filling with high-pressure nitrogen. For example, this can achieve an ultimate vacuum of 2 Pa inside the chamber 101.

[0086] The gas filling system is connected to the chamber 101 and is used to fill the chamber 101 with high-pressure nitrogen. Other structures of the gas filling system are not limited, as long as they can fill the chamber 101 with nitrogen and provide a pressurized nitrogen environment for welding.

[0087] In one possible implementation, the controller 800 includes a processor 802 and a memory 804 storing program instructions. The processor 802 is configured to execute the laser welding method for high-nitrogen stainless steel described below when the program instructions are executed.

[0088] Combination Figures 1 to 3 As shown, according to a second aspect of the embodiments of this application, a laser welding method for high-nitrogen stainless steel is provided, wherein a high-nitrogen stainless steel workpiece 200 is laser welded using the aforementioned laser welding apparatus 100 for high-nitrogen stainless steel. The laser welding method includes the following steps:

[0089] S301. In response to a welding request, obtain the operating parameters of the laser welding device, including the target operating pressure inside the chamber, the target gas flow rate of the side blowing system, the operating current of the magnetic field generator, the operating resistance of the sliding rheostat, and the laser power of the laser.

[0090] In response to a welding request, the processor 802 acquires the operating parameters of the laser welding apparatus 100, providing parameter preparation for controlling the laser welding apparatus 100 to perform laser welding of the high-nitrogen stainless steel workpiece 200.

[0091] In some embodiments, the workpiece 200 is made of high-nitrogen stainless steel, the chemical composition of which includes N, C, Si, Ni, Mn, Mo, V, and Cr. The target working pressure is calculated according to the following formula:

[0092] in,

[0093]

[0094]

[0095] In the formula, Work pressure to achieve goals To balance the calculated pressure under nitrogen solubility, The pressure is standard atmosphere, and k is an empirical coefficient. T The value represents the temperature of the molten pool formed when the laser beam acts on the workpiece 200. [%N] represents the mass percentage of nitrogen (N) in the high-nitrogen stainless steel, [%C] represents the mass percentage of carbon (C) in the high-nitrogen stainless steel, [%Si] represents the mass percentage of silicon (Si) in the high-nitrogen stainless steel, [%Ni] represents the mass percentage of nitrogen (Ni) in the high-nitrogen stainless steel, [%Mn] represents the mass percentage of mn (Mn) in the high-nitrogen stainless steel, [%Mo] represents the mass percentage of molybdenum (Mo) in the high-nitrogen stainless steel, [%V] represents the mass percentage of v (V) in the high-nitrogen stainless steel, and [%Cr] represents the mass percentage of chromium (Cr) in the high-nitrogen stainless steel. denoted as the coefficient of influence of the target working pressure on nitrogen activity, and H is the correction coefficient for nitrogen solubility.

[0096] In this embodiment, the chemical composition of the high-nitrogen stainless steel also includes Fe, etc. However, C, Si, Ni, Mn, Mo, V, and Cr elements have a significant impact on the solubility of nitrogen. Therefore, the target working pressure is calculated by the mass percentage of N, C, Si, Ni, Mn, Mo, V, and Cr in the high-nitrogen stainless steel to obtain a roughly optimal pressure value, thereby improving welding quality and reducing costs.

[0097] In one possible implementation, k is between 1.2 and 1.3.

[0098] S302. Based on the target working pressure, control the operation of the vacuum inflation system to expel the air inside the chamber and fill it with nitrogen, so that the pressure inside the chamber reaches the target working pressure.

[0099] The processor 802 controls the operation of the vacuum filling system 105 according to the target working pressure. By bringing the pressure inside the chamber 101 to the target working pressure, a pressurized nitrogen environment is provided for the laser welding of the high-nitrogen stainless steel workpiece 200, thereby improving the welding quality.

[0100] For example, the target vacuum level and target working pressure inside the chamber 101 can be obtained. Based on the target vacuum level, the vacuum inflation system 105 is controlled to operate to expel the air inside the chamber 101, so that the vacuum level inside the chamber 101 reaches the target vacuum level. Based on the target working pressure, the vacuum inflation system 105 is controlled to operate to fill the chamber 101 with nitrogen, so that the pressure inside the chamber 101 reaches the target working pressure.

[0101] S303. Control the operation of the side-blowing system according to the target gas flow rate, and blow auxiliary gas onto the workpiece at the target gas flow rate.

[0102] The processor 802 controls the operation of the side-blowing system according to the target gas flow rate, and blows auxiliary gas (nitrogen) onto the workpiece 200 at the target gas flow rate to disperse at least part of the plasma generated during the laser welding process, thereby reducing the plasma density floating on the surface of the workpiece 200, thereby increasing the welding energy, enhancing the coupling efficiency between the laser beam and the workpiece 200, and thus improving the weld depth and quality.

[0103] S304. Based on the operating current, control the magnetic field generator to operate at the operating current to generate a magnetic field inside the cabin.

[0104] The processor 802 controls the magnetic field generator to operate at the operating current to generate a magnetic field inside the chamber 101. It can also ensure that the magnetic induction intensity within the chamber 101 reaches and maintains a target magnetic induction intensity. This causes moving charged particles to be deflected by electromagnetic forces in the magnetic field, thereby deflecting at least a portion of the plasma, reducing the plasma density floating on the surface of the workpiece 200, increasing welding energy, enhancing the coupling efficiency between the laser beam and the workpiece 200, and ultimately improving weld depth and quality. The device used to measure the magnetic induction intensity is not limited.

[0105] S305. Based on the working resistance, control the sliding rheostat to operate at the working resistance to create an electric field inside the cabin.

[0106] The processor 802 controls the sliding rheostat 116 to operate at its operating resistance, based on the operating resistance, to create an electric field inside the chamber 101. It can also ensure that the electric field strength within the chamber 101 reaches and maintains a target electric field strength. This achieves the goal of increasing the velocity of charged particles through an external electric field, thereby increasing the degree of deflection and dispersing at least a portion of the plasma.

[0107] S306. Control the operation of the laser according to the laser power to emit a laser beam to the workpiece and perform laser welding on the welding area of ​​the workpiece.

[0108] The processor 802 controls the operation of the laser 111 based on the laser power, emitting a laser beam towards the welding area of ​​the workpiece 200 to perform laser welding on the welding area of ​​the workpiece 200, realizing laser welding under a pressurized nitrogen environment and improving welding quality. Specifically, the processor 802 can control the operation of the laser 111 and the laser welding head 110 to emit a laser beam with the target laser power towards the welding area of ​​the workpiece 200 to weld the workpiece 200.

[0109] The welding method in this embodiment is applicable to I-type, V-type, U-type and other welding bevels, and does not require additional special tooling or other auxiliary measures.

[0110] The welding method in this embodiment is simple, easy to implement, flexible, and highly safe. It can effectively reduce energy loss caused by plasma shielding, improve the stability of welding technology, significantly enhance the performance of welded joints, and reduce nitrogen escape and nitrogen porosity formation during the fusion welding of high-nitrogen stainless steel, thereby obtaining good weld structure and welding performance.

[0111] In some embodiments, the operating parameters also include the moving speed of the moving platform 114. While controlling the operation of the laser 111 according to the laser power, the laser welding method also includes: controlling the moving platform 114 to move at the moving speed to drive the workpiece 200 to move.

[0112] In this embodiment, the moving platform 114 is controlled to move at the moving speed to move the workpiece 200, so as to realize welding of the welding area of ​​the workpiece 200.

[0113] In some embodiments, the operating parameters also include the wire feeding speed of the wire feeding device 124. While controlling the operation of the laser 111 according to the laser power, the laser welding method also includes: controlling the operation of the wire feeding device 124 according to the wire feeding speed to feed welding wire to the welding area of ​​the workpiece 200 at the wire feeding speed.

[0114] In this embodiment, the wire feeding device 124 is controlled to operate according to the wire feeding speed, so as to feed the welding wire to the welding area of ​​the workpiece 200 at the wire feeding speed, thereby achieving smooth welding.

[0115] Combination Figure 4 As shown, this disclosure also provides a laser welding method for high-nitrogen stainless steel, comprising the following steps:

[0116] S401. In response to a welding request, obtain the operating parameters of the laser welding device, including the target operating pressure inside the chamber, the target gas flow rate of the side blowing system, the operating current of the magnetic field generator, the operating resistance of the sliding rheostat, and the laser power of the laser.

[0117] S402. Based on the target working pressure, control the operation of the vacuum inflation system to expel the air inside the chamber and fill it with nitrogen, so that the pressure inside the chamber reaches the target working pressure.

[0118] S403. Control the operation of the side-blowing system according to the target gas flow rate, and blow auxiliary gas onto the workpiece at the target gas flow rate.

[0119] S404. Based on the operating current, control the magnetic field generator to operate at the operating current to generate a magnetic field inside the cabin.

[0120] S405. Based on the working resistance, control the sliding rheostat to operate at the working resistance to create an electric field inside the cabin.

[0121] Steps S403, S404, and S405 can be executed simultaneously to prepare for welding.

[0122] S406. Based on the laser power, control the laser to operate, emitting a laser beam towards the workpiece to perform laser welding on the welding area of ​​the workpiece; simultaneously, based on the wire feeding speed, control the wire feeding device to operate, feeding welding wire to the welding area of ​​the workpiece at the wire feeding speed; simultaneously, based on the moving speed, control the moving platform to move at the moving speed to move the workpiece. The welding of the workpiece is then completed.

[0123] Example 1

[0124] (1) Perform workpiece 200 assembly and laser system 109 calibration.

[0125] Specifically, workpiece 200 uses two high-nitrogen stainless steel plates with a thickness of 6 mm. As shown in Table 1, the chemical composition and percentage of the high-nitrogen stainless steel plates by mass percentage are as follows: C 0.1wt%, Si 0.80wt%, Mn 18wt%, N 0.98wt%, Cr 18wt%, Ni 0.3wt%, Mo 2wt%, P 0.01wt%, S 0.001wt%, V 0.2wt%, with the remainder being Fe.

[0126] Table 1. Chemical composition and percentage (wt%) of high-nitrogen stainless steel sheet

[0127]

[0128] The V-shaped bevel is prepared by mechanical processing, with a bevel angle of 65°. Stainless steel wool and anhydrous ethanol are used to remove oxide scale, oil, and other impurities from the bevel and surrounding area.

[0129] Two processed high-nitrogen stainless steel plates are clamped together on a dedicated fixture of the welding moving platform 114. The center line of the bevel is calibrated using a laser collimation and positioning system to ensure that the butt joint deviation of the two high-nitrogen stainless steel plates is ≤0.1 mm. The laser 111 and laser welding head 110 are fixed outside the chamber 101. The laser beam emitted by the laser welding head 110 is guided into the chamber 101 through the double-sided coated pressure-resistant quartz glass of the transmission window 117 on the top of the chamber 101. The optical path is adjusted so that the laser beam is vertically focused on the center of the bevel, and the optical path offset is ≤0.2 mm.

[0130] (2) Expel the air from the cabin 101 and fill the cabin 101 with high-pressure nitrogen.

[0131] Specifically, mechanical pump 106 and Roots pump 107 are started to evacuate the air from chamber 101, creating a vacuum of 2 Pa. Then, high-purity nitrogen is introduced into chamber 101 at a flow rate of 0.1 MPa / min through the inflation system, maintaining a pressure of 1.2 MPa within chamber 101. The pressure inside chamber 101 is monitored in real time using a pressure gauge to ensure pressure fluctuations are ≤0.02 MPa, thus achieving pressure stability within chamber 101.

[0132] The pressure of 1.2 MPa inside the chamber 101 is obtained in the following manner.

[0133] The core molten pool temperature (i.e., the temperature of the liquid molten pool formed by the laser beam acting on the workpiece 200) obtained by infrared thermometry was 2100 ℃. As shown in Table 1, [%N] is 0.98 wt%, [%C] is 0.1 wt%, [%Si] is 0.80 wt%, [%Mn] is 18 wt%, [%Ni] is 0.3 wt%, [%Mo] is 2 wt%, [%V] is 0.2 wt%, and [%Cr] is 18 wt%. Standard atmospheric pressure. The pressure is 1.01325 MPa. Because nitrogen was introduced into chamber 101, the pressure inside chamber 101 is greater than standard atmospheric pressure. When > hour, The empirical coefficient k is set to 1.2.

[0134] The nitrogen solubility is calculated using the following formula. This equals 2.1 MPa, meaning that the optimal pressure required for this high-nitrogen stainless steel system to suppress nitrogen escape and the formation of nitrogen porosity defects is approximately 2.1 MPa.

[0135]

[0136] in,

[0137]

[0138]

[0139] (3) Welding process.

[0140] The industrial-grade closed-loop water cooling system is activated to circulate heat dissipation for the laser 111 and the laser welding head 110.

[0141] Turn on the magnetic field generator to create a magnetic field inside the chamber 101. Turn on the power supply 115 to create an electric field inside the chamber 101. Turn on the side-blowing system to blow nitrogen gas onto the workpiece 200 through the side-blowing nozzles 112.

[0142] The laser power is set to 6 kW, and the moving platform 114 is simultaneously started to move horizontally along the guide rail at a speed of 1.0 m / min. The wire feeder (wire feeding device 124) feeds the welding wire at a preset wire feeding speed, so that the end of the welding wire is always located 1 mm to 2 mm from the front edge of the molten pool.

[0143] Start the fan 119, and remove the welding fumes through the three-stage filtration assembly 120 consisting of a filter screen, activated carbon, and a HEPA high-efficiency filter.

[0144] Three high-speed cameras can simultaneously capture dynamic images of the laser-molten pool. Thermocouples can record temperature changes in real time during the welding process.

[0145] (4) Post-weld treatment and quality inspection.

[0146] After welding, maintain nitrogen pressure, cool for 10 minutes, and then slowly depressurize to atmospheric pressure to avoid stress cracks in the workpiece due to sudden pressure drop.

[0147] Open the pressure chamber door 103, remove the welded workpiece 200, and remove the fixture using special tools. Inspect the double-sided coated pressure-resistant quartz glass of the transmission window 117 and clean any spatter inside the chamber 101. Apply special grease to moving parts such as the guide rails and wire feeder to extend equipment life. Shut down all systems, record complete parameters and monitoring data such as pressure, power, and speed of this welding operation, and archive the data.

[0148] The weld surface is photographed using a high-definition camera to check for defects such as porosity, cracks, and undercut. The nitrogen content of the workpiece is then tested.

[0149] The inspection results showed that the 6 mm high-nitrogen stainless steel sheet was completely penetrated, with clear fusion lines on both sides of the weld, a weld reinforcement of 0.3 mm, a width uniformity deviation of 0.1 mm, and virtually no macroscopic defects such as porosity, cracks, or undercut on the surface. Real-time observation through the monitoring system showed high molten pool stability, controllable laser plasma behavior, and virtually no nitrogen porosity caused by nitrogen escape. Post-weld testing indicated that the nitrogen content in the weld zone was 0.96%, reaching 98% of the base material, meeting the requirements for the use of high-nitrogen stainless steel in transportation, marine engineering, and other fields.

[0150] Comparative Example 1

[0151] The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 does not form a magnetic field and an electric field inside the cabin 101.

[0152] The rest of the contents of Comparative Example 1 are the same as those of Example 1.

[0153] The welded workpiece 200 was inspected, and the results are as follows:

[0154] The 6 mm high-nitrogen stainless steel sheet was not fully penetrated, resulting in a gap on the back of the weld. The fusion lines on both sides of the weld were clear, the weld reinforcement was 0.5 mm, the width uniformity deviation was 0.3 mm, and there were a few pores and cracks on the surface. Real-time monitoring showed fluctuations in the molten pool, indicating uncontrollable laser plasma behavior. Post-weld testing revealed that the nitrogen content in the weld zone was 0.89%, reaching 91% of the base material, which does not meet the requirements for the use of high-nitrogen stainless steel in transportation, marine engineering, and other fields.

[0155] Comparative Example 2

[0156] The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 did not involve side-blowing nitrogen gas inside the cabin 101.

[0157] The rest of the contents of Comparative Example 2 are the same as those of Example 1.

[0158] The welded workpiece 200 was inspected, and the results are as follows:

[0159] The 6 mm high-nitrogen stainless steel sheet was not fully penetrated, resulting in a gap on the back of the weld. The fusion lines on both sides of the weld were clear, the weld reinforcement was 0.4 mm, the width uniformity deviation was 0.4 mm, and there were a few pores and cracks on the surface. Real-time observation through the monitoring system showed fluctuations in the molten pool, indicating uncontrollable laser plasma behavior. Post-weld testing showed that the nitrogen content in the weld zone was 0.89%, reaching 91% of the base material, which does not meet the requirements for the use of high-nitrogen stainless steel in transportation, marine engineering, and other fields.

[0160] Comparative Example 3

[0161] The difference between Comparative Example 3 and Example 1 is that Comparative Example 3 does not form a magnetic field or electric field inside the cabin 101, nor does it have a side-blowing system.

[0162] The welded workpiece 200 was inspected, and the results are as follows:

[0163] The 6 mm high-nitrogen stainless steel sheet was not fully penetrated, resulting in a gap on the back of the weld. The fusion lines on both sides of the weld were clear, the weld reinforcement was 1 mm, and the width uniformity deviation was 2 mm. Macroscopic defects such as localized porosity, cracks, and undercut were observed on the surface. Real-time monitoring showed violent fluctuations in the molten pool and periodic occurrences of laser plasma, which reduced the laser energy transmission to the workpiece, affecting the welding process and quality. Post-weld testing indicated that the nitrogen content in the weld zone was 0.88%, only 90% of that in the base material, failing to meet the requirements for high-nitrogen stainless steel in transportation, marine engineering, and other fields.

[0164] This disclosure provides a controller 800, the structure of which is as follows: Figure 5 As shown, it includes:

[0165] The processor 802 and memory 804 may further include a communication interface 806 and a bus 808. The processor 802, communication interface 806, and memory 804 can communicate with each other via the bus 808. The communication interface 806 can be used for information transmission. The processor 802 can call logical instructions in the memory 804 to execute the laser welding method for high-nitrogen stainless steel described in the above embodiment.

[0166] The memory 804, as a computer-readable storage medium, can be used to store software programs and computer-executable programs, such as the program instructions / modules corresponding to the methods in the embodiments of this disclosure. The processor 802 executes functional applications and data processing by running the program instructions / modules stored in the memory 804, thereby implementing the laser welding method for high-nitrogen stainless steel in the above method embodiments. Therefore, it possesses all the beneficial effects of the above embodiments, which will not be elaborated further here.

[0167] The memory 804 may include a program storage area and a data storage area. The program storage area may store the operating system and application programs required for at least one function; the data storage area may store data created based on the use of the terminal device. Furthermore, the memory 804 may include high-speed random access memory and may also include non-volatile memory.

[0168] This disclosure provides a computer-readable storage medium storing computer-executable instructions configured to perform the aforementioned laser welding method for high-nitrogen stainless steel.

[0169] The aforementioned computer-readable storage medium may be a transient computer-readable storage medium or a non-transitory computer-readable storage medium.

[0170] The foregoing description and accompanying drawings fully illustrate embodiments of the present disclosure to enable those skilled in the art to practice them. Other embodiments may include structural, logical, electrical, procedural, and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Parts and features of some embodiments may be included in or replace parts and features of other embodiments. The scope of the embodiments of this disclosure includes the entire scope of the claims and all available equivalents of the claims. When used in this application, although the terms “first,” “second,” etc., may be used in this application to describe elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, a first element may be called a second element without changing the meaning of the description, and similarly, a second element may be called a first element, provided that all occurrences of “first element” are consistently renamed and all occurrences of “second element” are consistently renamed. First element and second element are both elements, but may not be the same element. Moreover, the terminology used in this application is only for describing embodiments and is not intended to limit the claims. As used in the description of the embodiments and claims, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” are intended to also include the plural forms. Similarly, the term “and / or” as used herein means including one or more of the associated listed elements and all possible combinations thereof. Additionally, when used in this application, the terms “comprise” and its variations “comprises” and / or “comprising” refer to the presence of stated features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof. Without further limitations, an element defined by the phrase “comprising an…” does not exclude the presence of additional identical elements in the process, method, or apparatus that includes said element. In this document, each embodiment may focus on the differences from other embodiments, and similar or identical parts between embodiments can be referred to mutually. For methods, products, etc., disclosed in the embodiments, if they correspond to the method section disclosed in the embodiments, the relevant parts can be referred to the description of the method section.

[0171] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the embodiments of this disclosure. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0172] The methods and products disclosed in the embodiments herein (including but not limited to devices and equipment) can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of units may be merely a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. In addition, the coupling or direct coupling or communication connection shown or discussed between each other may be through some interfaces, and the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to implement this embodiment according to actual needs. In addition, the functional units in the embodiments of this disclosure may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0173] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions marked in the blocks may occur in a different order than that shown in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, or they may be executed in reverse order, depending on the functions involved. In the descriptions corresponding to the flowcharts and block diagrams in the accompanying drawings, the operations or steps corresponding to different blocks may also occur in a different order than disclosed in the description, and in some cases, there is no specific order between different operations or steps. For example, two consecutive operations or steps may actually be executed substantially in parallel, or they may be executed in reverse order, depending on the functions involved. Each block in a block diagram and / or flowchart, and combinations of blocks in a block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

Claims

1. A laser welding apparatus for high nitrogen stainless steel, characterized by, The laser welding device comprises: a cabin, a moving platform is arranged in the cabin, and a workpiece is placed on the moving platform; a laser and a laser welding head connected to each other are arranged outside the cabin and used for emitting a laser beam to the workpiece; a vacuum gas charging system in communication with the cabin is used for discharging air in the cabin and charging nitrogen into the cabin, so as to provide a pressurized nitrogen environment for laser welding of the workpiece; a side blowing system comprising a side blowing nozzle arranged in the cabin; a magnetic field generator arranged in the cabin is used for forming a magnetic field in the cabin; a power supply, a positive electrode of the power supply is electrically connected to the laser welding head; a sliding rheostat, one end of the sliding rheostat is electrically connected to a negative electrode of the power supply, and the other end of the sliding rheostat is electrically connected to the moving platform; wherein the laser welding head, the power supply, the sliding rheostat and the moving platform can form an electric field in the cabin; wherein, during laser welding of the workpiece, the side blowing nozzle blows auxiliary gas to the workpiece to disperse at least part of the plasma generated in the laser welding process; the magnetic field and the electric field formed in the cabin act in concert to accelerate and deviate at least part of the plasma floating on the surface of the workpiece.

2. The laser welding device according to claim 1, wherein: an included angle between a blowing direction of the side blowing nozzle and a surface of the workpiece is 30° to 50°; and / or a distance between a blowing port of the side blowing nozzle and the surface of the workpiece is 12 mm to 18 mm; and / or a blowing flow rate of the side blowing system is 40 L / min to 60 L / min.

3. The laser welding apparatus of claim 1, wherein, Further comprising: a transmission window arranged on a cabin wall of the cabin; the laser beam emitted by the laser welding head passes through the transmission window to a welding area of the workpiece.

4. The laser welding apparatus of claim 1, wherein, Further comprising: a purification pipe, an inlet of the purification pipe is directed to the workpiece; a fan arranged in the purification pipe is used for sucking smoke and dust generated in the welding process into the purification pipe; a filter assembly arranged in the purification pipe and located on an air outlet side of the fan, the filter assembly comprises a first filter, a second filter and a third filter arranged in sequence along a gas flow direction in the purification pipe; wherein the smoke and dust are filtered by the filter assembly and then flow out of the purification pipe into the cabin.

5. The laser welding apparatus of claim 1, wherein, Further comprising: a wire feeding device arranged in the cabin and used for conveying a welding wire during laser welding.

6. The laser welding apparatus of claim 1, wherein, The vacuum gas charging system comprises: a vacuum system comprising a mechanical pump and a Roots pump, an inlet of the Roots pump is in communication with the cabin, an outlet of the Roots pump is in communication with an inlet of the mechanical pump, and the vacuum system is used for discharging air in the cabin; a gas charging system in communication with the cabin is used for charging nitrogen into the cabin.

7. A laser welding method for high-nitrogen stainless steel, applied to the laser welding apparatus for high-nitrogen stainless steel according to any one of claims 1 to 6, characterized by, The laser welding method comprises the following steps: in response to a welding request, obtaining working parameters of a laser welding device, the working parameters comprising a target working pressure in the cabin, a target gas flow rate of a side blowing system, a working current of a magnetic field generator, a working resistance of a sliding rheostat and a laser power of a laser; According to the target working pressure, the vacuum charging system is controlled to operate to discharge air in the cabin and charge nitrogen into the cabin, so that the pressure in the cabin reaches the target working pressure; According to the target gas flow rate, the side blowing system is controlled to operate to blow auxiliary gas to the workpiece at the target gas flow rate; According to the working current, the magnetic field generator is controlled to operate at the working current to form a magnetic field in the interior of the cabin; According to the working resistance, the slide rheostat is controlled to operate at the working resistance to form an electric field in the interior of the cabin; According to the laser power, the laser is controlled to operate to emit a laser beam to the workpiece to perform laser welding on the welding area of the workpiece.

8. The laser welding method according to claim 7, characterized in that, The working parameters further include a moving speed of a moving platform, and when the step of controlling the laser to operate according to the laser power is performed, the laser welding method further includes: According to the moving speed, the moving platform is controlled to move at the moving speed to drive the workpiece to move.

9. The laser welding method according to claim 7, characterized by, The working parameters further include a wire feeding speed of a wire feeding device, and when the step of controlling the laser to operate according to the laser power is performed, the laser welding method further includes: According to the wire feeding speed, the wire feeding device is controlled to operate to feed a welding wire to the welding area of the workpiece at the wire feeding speed.

10. The laser welding method according to claim 7, wherein the material of the workpiece is a high nitrogen stainless steel, and a chemical composition of the high nitrogen stainless steel includes N, C, Si, Ni, Mn, Mo, V, and Cr, characterized in that, The target working pressure is calculated according to the following formula: wherein, wherein Ptarget is the target working pressure, Pcal is the calculated pressure at equilibrium nitrogen solubility, P0 is the standard atmospheric pressure, and k is an empirical coefficient, T T is the temperature of the liquid melt pool formed by the laser beam acting on the workpiece, [%N] is the mass percentage of N in the high-nitrogen stainless steel, [%C] is the mass percentage of C in the high-nitrogen stainless steel, [%Si] is the mass percentage of Si in the high-nitrogen stainless steel, [%Ni] is the mass percentage of Ni in the high-nitrogen stainless steel, [%Mn] is the mass percentage of Mn in the high-nitrogen stainless steel, [%Mo] is the mass percentage of Mo in the high-nitrogen stainless steel, [%V] is the mass percentage of V in the high-nitrogen stainless steel, and [%Cr] is the mass percentage of Cr in the high-nitrogen stainless steel, Ptarget is the target working pressure, and H is the nitrogen solubility correction coefficient.

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