Laser-electric arc hybrid welding method for high-grade silicon steel

Abstract

The invention relates to the technical field of strip steel welding technologies and material science, in particular to a laser-arc hybrid welding method for high-grade silicon steel. The method comprises the following steps that two to-be-welded strip steel plates are clamped; the welding ends of the two to-be-welded strip steel plates are sheared respectively; splicing the two cut strip steel plates to be welded; and the two to-be-welded strip steel plates are subjected to preheating, laser-arc hybrid welding and heat treatment. According to the laser-arc hybrid welding method for the high-grade silicon steel, the hot-rolled high-grade silicon steel is welded through the combined process of laser-arc hybrid welding, preheating and postweld heat treatment, the quality of a welded joint can be effectively improved, and the welded joint of a product is good in toughness and not prone to strip breakage. The method is simple in process, convenient to operate and low in production cost.

Description

Technical Field

[0001] The present invention relates to the fields of strip steel welding technology and material science and technology, and in particular to a laser arc composite welding method for high-grade silicon steel. Background Art

[0002] The silicon steel normalizing pickling unit uses a laser welder to weld the head and tail of the strip to ensure the continuity of the production line. The raw material entering the normalizing pickling unit is hot-rolled silicon steel. There are three types of laser welding processes: laser, laser welding with wire, and laser arc hybrid welding. However, the weld performance of high-grade silicon steel welded by pure laser and laser welding with wire is unstable, and the welding success rate is low, which cannot meet the requirements of large-scale, efficient, and continuous production. In addition, the carbon dioxide gas lasers currently used in steel mills are gradually being replaced by high-power solid-state lasers represented by fiber lasers and disk lasers due to their high price, complex structure, difficult maintenance, and high operating costs. Therefore, the original welding process based on carbon dioxide gas lasers can no longer meet the application requirements of solid-state lasers.

[0003] Hot-rolled high-grade non-oriented silicon steel has a high Si content, the weld structure after welding is coarse, the heat-affected zone structure is greatly affected by the welding heat input, the structure uniformity is poor, and the weld joint toughness is poor. When using this welding process to weld silicon steel welds, even if the surface morphology is full, it will fail to pass the bending test on the weld inspection bending machine. This type of weld is prone to cracking and breaking along the weld or heat-affected zone when the unit is running, reducing production efficiency. Summary of the Invention

[0004] In order to solve the above-mentioned deficiencies in the prior art, the present invention provides a laser arc hybrid welding method for high-grade silicon steel.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: A laser arc hybrid welding method for high-grade silicon steel comprises the following steps: Clamp the second steel plate to be welded; Shearing the welding ends of the two steel plates to be welded respectively; Splicing the two sheared steel plates to be welded; The two steel plates to be welded are preheated, laser arc hybrid welded, and heat treated.

[0006] In one embodiment, the thicknesses of the two steel plates to be welded are h1 and h2 respectively; wherein, h1≤h2, h2-h1≤0.8mm, and h2≤1.3h1.

[0007] In one embodiment, the preheating is online preheating; the preheating temperature is above 300° C. and below 400° C.

[0008] In one embodiment, the heat treatment is an online heat treatment; the temperature of the heat treatment is above 700° C. and below 800° C.

[0009] In one embodiment, the distance between the laser and the welding wire in the laser arc hybrid welding is greater than 2 mm and less than 5 mm.

[0010] In one embodiment, the gap between the two steel plates to be welded after being sheared and butted is greater than 0.2 mm and less than 0.3 mm.

[0011] In one embodiment, the laser arc hybrid welding is a single-sided welding method for welding the inter-plate gap between the two steel strips.

[0012] In one embodiment, the laser arc hybrid welding is performed by a laser arc hybrid welding head; Induction heating coils are respectively arranged in front of and behind the laser arc hybrid welding head along the extending direction of the weld to perform preheating and heat treatment.

[0013] In one embodiment, the laser arc hybrid welding adopts a single-sided welding method to weld the gap between two steel strips to be welded.

[0014] In one embodiment, during welding, a shielding gas is blown toward the welding part; The shielding gas blown toward the front of the weld is a mixed shielding gas; The shielding gas blown to the back of the weld is a single-component shielding gas; Preferably, the mixed protective gas consists of argon and 18% carbon dioxide; Preferably, the flow rate of the mixed protective gas is greater than 25 L / min and less than 30 L / min; Preferably, the pressure of the mixed protective gas is greater than 0.4 MPa and less than 0.6 MPa; Preferably, the single-component protective gas is argon; Preferably, the flow rate of the single-component protective gas is greater than 8 L / min and less than 15 L / min; Preferably, the pressure of the single-component protective gas is greater than or equal to 0.4 MPa and less than or equal to 0.6 MPa.

[0015] Based on the above, compared with existing technologies, the laser arc hybrid welding method for high-grade silicon steel provided by the present invention utilizes a combined process of laser arc hybrid welding, preheating, and post-weld heat treatment to weld hot-rolled high-grade silicon steel. This method effectively improves the quality of welded joints, resulting in welded joints with excellent toughness and resistance to breakage. The method also features simple processing, easy operation, and low production costs.

[0016] Other features and beneficial effects of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The objectives and other beneficial effects of the present invention can be achieved and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work. The positional relationships shown in the drawings in the following description are based on the directions of the components drawn in the drawings unless otherwise specified.

[0018] Figure 1 Shown is a process flow chart of a laser arc hybrid welding method for high-grade silicon steel provided by an embodiment of the present invention; Figure 2 What is shown is a schematic diagram of the welding process structure provided by an embodiment of the present invention; Figure 3 What is shown is the microstructure image of the weld of the product according to the embodiment of the present invention; Figure 4 Shown is a photo of the weld of the product of the embodiment of the present invention after the cupping test; Figure 5 Shown is a photo of the weld of the product of Comparative Example 1 of the present invention after the cupping test; Figure 6 Shown is a photo of the weld of the product of Comparative Example 2 of the present invention after the cupping test; Figure 7 Shown is a photo of the weld of the product of Comparative Example 3 of the present invention after the cupping test; Figure 8 Shown is a photograph of the weld of the product of Comparative Example 4 of the present invention after the cupping test. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments; the technical features designed in different implementation modes of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0020] In the description of the present invention, it should be noted that all terms used in the present invention (including technical terms and scientific terms) have the same meanings as those generally understood by ordinary technicians in the field to which the present invention belongs, and should not be understood as limiting the present invention; it should be further understood that the terms used in the present invention should be understood to have the same meanings as these terms in the context of this specification and the relevant field, and should not be understood in an idealized or overly formal sense, unless explicitly defined as such in the present invention.

[0021] Please refer to Figure 1 The embodiment of the present invention provides a laser arc hybrid welding method for high-grade silicon steel, comprising the following steps: Step 1, clamping the second steel plate to be welded; In this embodiment, the two steel strips to be welded are clamped by a clamping device on the welding machine to fix the position of the steel strips to be welded, ensuring that the steel strips will not shift or shake during the subsequent shearing, seaming, and welding processes, thereby ensuring the accuracy and quality of the welding. The high-grade silicon steel refers to silicon steel with a silicon content of 2.7% or above (mass ratio). Such silicon steel grades require a laser welder to weld the head and tail of the silicon steel strips during continuous production in normal pickling units and continuous rolling mills to ensure the continuity of the production line. Specific operations include but are not limited to: Choose the right clamp: Based on the size, shape, and thickness of the steel strip to be welded, select a clamp with sufficient clamping force and stability. For example, for thinner steel strips, a magnetic clamp can be used, which can apply the clamping force evenly to avoid deformation of the steel strip; for thicker steel strips, a mechanical clamp, such as a hydraulic clamp, may be required to provide greater clamping force. Determine the clamping position: The clamp should be placed at the appropriate position of the steel plate to ensure a secure clamping without affecting the subsequent shearing and welding operations. Generally speaking, the clamp should be close to the part to be welded, but leave enough space for the operation of the shearing tool and the movement of the welding head; Adjust the clamping force: The clamping force should be moderate. Too much may cause the strip to deform, while too little may not ensure the fixation of the strip. The clamp adjustment device can be used to adjust the clamping force to the appropriate level according to the material and thickness of the strip.

[0022] In some preferred embodiments, the thicknesses of the two steel plates to be welded are h1 and h2, respectively, wherein h1≤h2, h2-h1≤0.8mm, and h2≤1.3h1. It should be noted that the steel strips to be welded are welded with the lower surface flush. The greater the thickness difference of the steel strips to be welded, the greater the difference in cross-sectional stress on both sides of the thin and thick plates. Compared with thick plate materials, thin plates have lower resistance to deformation and withstand greater deformation during deformation. The tensile stress of the thin plates in the area near the weld is also greater. With reference to the metal cupping test standard (GB / T4156-2020), a cupping test is performed on the weld. When the weld cups, the cracks at the rupture do not tear along the weld, ensuring that the strength at the weld is greater than the strength of the parent material. Combined with the actual cupping test results, the preferred thickness difference and thickness ratio, within this range, this welding method can achieve a good cupping effect.

[0023] Step 2: Shearing the welding ends of the two steel plates to be welded respectively; In this embodiment, the welding ends of the two steel plates to be welded are sheared separately to provide the welding ends with flat and vertical shear surfaces, thereby removing possible defects such as burrs and oxide layers, and ensuring the quality of the welded joint and the stability of the welding. Specific operations include but are not limited to: Selecting shearing equipment: Choose the appropriate shearing equipment based on the thickness and material of the strip. For thinner strips, a double shear can be used, which has a fast shearing speed and high precision. For thicker strips, a hydraulic shear may be required to provide sufficient shearing force.

[0024] Adjust shearing parameters, including shear gap and shear speed. The shear gap must be precisely adjusted based on the thickness of the strip. A gap that is too small may cause increased tool wear, while a gap that is too large may result in an uneven shear surface. The shearing speed should be moderate; a speed that is too fast may cause tearing on the shear surface, while a speed that is too slow may affect production efficiency.

[0025] Perform shearing operations: During the shearing process, ensure that the position of the steel strip is fixed and the tool movement trajectory is accurate. At the same time, the shearing surface should be inspected. If there are any defects such as burrs and cracks, they should be cleaned and repaired in time.

[0026] Step 3, joining the two sheared steel plates to be welded; In this embodiment, the two sheared steel plates to be welded are seamed to ensure that the welded ends of the steel plates to be welded fit tightly together, forming a good weld joint, reducing the occurrence of welding defects, and improving welding quality. Specific operations include but are not limited to: Check the gap between the weld seams: The gap between the weld seams should be kept within a small range, generally not exceeding a certain percentage of the strip steel plate thickness (e.g., 0.1-0.2 times). If the gap between the weld seams is too large, the weld seam will be poorly formed during welding, and defects such as insufficient weld filler and weld leakage may occur. If the gap between the weld seams is too small, the filler metal melted by the welding wire at the weld seam will not fully fuse with the base metal in the molten pool, and the filler metal will accumulate on the upper surface of the weld seam, resulting in excessive weld reinforcement.

[0027] Adjust the position of the strip steel plates: Use the fine-tuning device to align the weld ends of the two strip steel plates to ensure the straightness and verticality of the joint. Displacement sensors or other instruments and equipment can be used to assist in adjustment and improve the accuracy of the joint.

[0028] Fix the joint position: After the joint is adjusted, use a temporary fixing device (such as a clamp, etc.) to fix the steel plate to prevent the joint position from changing during the welding process.

[0029] It is worth noting that for the above-mentioned step 1 of "clamping the two steel plates to be welded", step 2 of "shearing the welding ends of the two steel plates to be welded respectively", and step 3 of "joining the sheared two steel plates to be welded", those skilled in the art can also refer to other existing hot-rolled high-grade non-oriented silicon steel welding related operating procedures, which will not be elaborated here.

[0030] Step 4: preheating, laser arc hybrid welding, and heat treatment of the two steel plates to be welded.

[0031] In this embodiment, the laser arc hybrid welding process uses a push-pull wire system CMT process for arc welding, a solid-state laser for laser welding, and an induction heater for induction heating that is driven by a trolley and ensures coordinated movement with the arc welder and the laser welder. The laser arc hybrid welding process can use laser arc paraxial hybrid welding. The molten pool of laser-guided arc hybrid welding is relatively stable, and when the arc acts from the rear, the heat input brought in by the arc, combined with preheating before welding, can effectively reduce the cooling rate of the molten pool, which is conducive to the overflow of pores and reduces the probability of pore defects. In laser-guided arc hybrid welding, the role of the laser is mainly to attract and stabilize the arc in the front, reducing the deviation of the arc during welding to obtain better weld formation.

[0032] The preheating is online, and the heat treatment is online. During laser arc hybrid welding, the unwelded seam is preheated, and the completed weld undergoes post-weld heat treatment. Laser arc hybrid welding is performed using a laser arc hybrid welding head. An electromagnetic induction coil is positioned in front of the head along the weld extension for online preheating, and an induction heating coil is positioned behind the head for online post-weld heat treatment.

[0033] It should be noted that preheating before welding, by preheating the weld zone and preheating the steel plates to be welded, can improve the laser's absorption rate while reducing the heat input required for subsequent laser and arc welding. More importantly, preheating before welding reduces the impact of rapid temperature changes in the weld zone caused by the heat input of laser-arc hybrid welding during actual welding, while also reducing welding stress in the weld zone and avoiding the formation of hardened microstructures. Furthermore, the CMT process used in arc welding significantly reduces the heat input during welding, thereby reducing the thermal impact on the weld microstructure and better ensuring the microstructure and properties of the weld.

[0034] Please refer to Figure 2 In this embodiment, the preheating and heat treatment can be achieved through the following structure: the laser arc hybrid welding is performed using a laser arc hybrid welding head, and induction heating coils are respectively positioned in front of and behind the laser arc welding head along the weld extension direction to perform online preheating and post-weld heat treatment operations. It can be understood that the front of the laser arc hybrid welding head is the unwelded side of the joint, and the rear is the formed side of the weld. The laser arc hybrid welding head, online preheating, and online post-weld heat treatment devices are all mounted on a welding carriage, which is driven by the carriage and moves along the weld direction. The laser arc hybrid welding head is mounted above the steel strip, and the induction heating coil is mounted on the underside of the steel strip. The online preheating and post-weld heat treatment devices operate at the same speed as the welding speed. The three devices work together to ensure weld quality.

[0035] In the embodiment of the present invention, the pre-welding preheating induction coil, the laser welding head, the arc welding gun hybrid welding device and the post-welding heat treatment induction coil are all arranged on the welding carriage. The pre-welding preheating + intermediate laser arc hybrid welding + post-welding heat treatment three parts are carried out simultaneously without waiting time. The pre-welding preheating is followed by the intermediate welding and finally the post-welding heat treatment. After the welding is completed, the heat treatment is also completed. In an embodiment of the present invention, the heating temperature range of the preheating induction coil used for preheating is above 300°C and below 400°C, and the heating temperature of the preheating induction coil is, for example, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, etc., but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable; the heating temperature range of the post-weld heat treatment is above 700°C and below 800°C, and the heating temperature of the post-weld heat treatment is, for example, 700°C, 710°C, 720°C, 730°C, 740°C, 750°C, etc. ℃, 760℃, 770℃, 780℃, 790℃, 800℃ or any value therebetween; through preheating before welding, on the one hand, the preheating can slow down the cooling rate after welding and reduce the welding stress in the welding area; on the other hand, it can increase the laser absorption efficiency, reduce the laser input power, increase the molten pool depth, maintain the heat input of the molten pool, make the molten pool area more fluid, facilitate the arc stirring of the molten pool, accelerate the fusion of the wire droplet and the base material, and enable the phase change to proceed fully, further improve the weld microstructure and performance, facilitate the escape of gas in the welding molten pool, reduce defects such as pores, cracks, and undercuts, improve the weld quality, and be more conducive to the improvement of the weld microstructure and performance. Post-weld heat treatment further releases welding stress, reduces the formation of hardened structure, improves weld microstructure and performance, improves weld toughness and cold crack resistance, and reduces the risk of broken belts on the production line. In addition, the cooling of the post-weld heat treatment in the present invention can be directly cooled in the air without the need to specifically control the cooling rate, which greatly simplifies the heat treatment process.

[0036] The laser arc hybrid welding used in the present invention has the following advantages over the laser wire welding process: (1) Higher welding stability: The optical plasma provides sufficient charged particles for stable arc combustion, making the arc burning stable and attracting the arc, making it less likely for the arc to drift or break during high-speed welding. At the same time, the filler material enters the molten pool in the form of molten droplets, and the laser beam has a strong pulling effect on the arc and the droplets, thus effectively overcoming the disadvantage of the high relative position accuracy requirement of the laser beam and the welding wire in solid laser-filler wire welding; (2) Better weld formation and joint quality: The composite heat source can effectively slow down the solidification rate of the molten pool metal during welding, allowing the phase transformation to proceed fully, which is conducive to the escape of gas in the welding pool and improves the weld quality. It reduces defects such as pores, cracks, and undercuts. The weld is fuller and the weld width is increased by 50%. Combined with the melting of the welding wire droplet, it effectively improves and enhances the weld structure and properties, thereby obtaining better weld quality and meeting the welding requirements of difficult-to-weld materials such as high-grade silicon steel.

[0037] (3) Higher welding efficiency and lower welding cost: The arc provides preheating and directly melts the welding wire without consuming laser energy, thus enhancing the laser keyhole penetration ability, thereby increasing the welding penetration depth and welding speed. The welding efficiency is increased by 20%-30%, and the welding thickness can reach 10mm. At the same time, the reflectivity of the molten metal surface is lower than that of the solid metal surface. When the laser irradiates the liquid molten pool of the base material, the base material can absorb more laser energy and increase the melting depth. Compared with single laser welding of the same power, the composite heat source welding increases the penetration depth by more than 50% on average, ensuring that the welding speed can be increased by 1-2 times under the same penetration depth conditions. This means reducing the power level of the laser, improving efficiency, and thus reducing welding costs.

[0038] (4) Higher process adaptability: The addition of the arc increases the width of the fusion zone on the workpiece surface, making laser-arc hybrid welding less sensitive to assembly gaps, centering, and misalignment. Compared with laser welding or laser wire welding, it has a higher tolerance for joint gaps and misalignment, and can tolerate a joint gap of 0.5 mm and a misalignment of 50%.

[0039] The welding process parameters are selected as follows: Obtain the thicknesses of the two strips to be welded, h1 and h2, respectively, which must meet the following preset conditions: h1 ≤ h2, h2-h1 ≤ 0.8 mm, and h2 ≤ 1.3 h1. Based on the total thickness of the two strips to be welded, obtain the corresponding welding process parameters from the welding database, including welding speed, laser power, laser defocus, seam gap, welding voltage, welding current, preheating power, and post-weld heat treatment power. The specific welding parameters are as follows: Table 1

[0040] In this embodiment, the laser arc hybrid welding speed is 3 m / min. The laser is a fiber laser. The laser defocus is 5 ± 0.5 mm. The distance between the laser (laser) and the wire (welding wire) in the laser arc hybrid welding is greater than 3 mm and less than 5 mm, for example, 3 mm, 4 mm, 5 mm, or any value therebetween. The gap between the two steel plates to be welded after shearing and butting is greater than 0.2 mm and less than 0.3 mm, for example, 0.21 mm, 0.22 mm, 0.23 mm, 0.24 mm, 0.25 mm, 0.26 mm, 0.27 mm, 0.28 mm, 0.29 mm, 0.30 mm, or any value therebetween. The welding wire is a carbon steel wire (50C6) with a diameter of 1.0 mm. The wire dry extension is 10-15 mm, for example, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, or any value therebetween.

[0041] The laser arc hybrid welding is a single-sided welding method for welding the inter-plate gap between the two steel strips. The distance between the preheating and post-weld heat treatment station and the welding station is 3±0.5mm. During the laser arc hybrid welding process, a shielding gas is blown toward the welding part, wherein the shielding gas blown toward the front of the weld is a mixed shielding gas; the shielding gas blown toward the back of the weld is a single-component shielding gas; the shielding gas toward the front of the weld is blown out by an electric welding gun, and is a mixed gas (argon + 18% carbon dioxide), with a flow rate of more than 25L / min and less than 30L / min, such as 25L / min, 26L / min, 27L / min, 28L / min, 29L / min, 30L / min or any value therebetween, and a pressure of more than 0.4MPa and less than 0.6MPa. The shielding gas on the back of the weld is argon (purity 99.99%) with a flow rate of 8 L / min or more and 15 L / min or less, such as 8 L / min, 9 L / min, 10 L / min, 11 L / min, 12 L / min, 13 L / min, 14 L / min, 15 L / min or any value therebetween; the pressure is 0.4 MPa or more and 0.6 MPa or less, such as 0.4 MPa, 0.5 MPa, 0.6 MPa or any value therebetween.

[0042] Experimental results showing the technical advantages of the present invention will be described below using Examples and Comparative Examples.

[0043] Example Laser welding uses a fiber solid-state laser. The two steel strips to be welded are W250 and W300, with Si contents of 3.25% and 2.95% respectively. The thicknesses h1 and h2 are 2.2 mm and 2.5 mm respectively, with a total thickness of 4.7 mm. Two steel strips are clamped, sheared, and seamed, with the seam then welded using laser arc hybrid welding. During the welding process, shielding gas is blown to protect the upper and lower surfaces of the weld area. The welding method is single-sided, and online preheating and post-weld heat treatment are implemented during the welding process.

[0044] The welding process parameters are as follows: The laser arc hybrid welding speed is 3m / min, the laser power is 2.5kW, the laser defocus is 5mm, the welding voltage is 15.4V, the welding current is 127A, the online preheating temperature is about 350℃, the matching online preheating power is 7±0.5kW, the online post-heating temperature is about 750℃, and the online post-weld heat treatment power is 12±0.5kW.

[0045] There are no cracks in the weld, no cracks in the weld, the weld and heat-affected zone have uniform structure, the weld performance is good, and no weld breakage occurs during product operation.

[0046] For example, the microstructure image of the weld is as follows Figure 3 As shown in the figure, the grain size of the weld fusion zone and heat affected zone is relatively uniform.

[0047] Weld performance is primarily assessed through a cupping test combined with a weld bend test, based on the Metal Cupping Test Standard (GB / T4156-2020). The cupping test is performed based on the absence of cracks along the weld seam. This method is widely used to assess weld quality in plate and strip production and will not be elaborated on here.

[0048] See also Figure 4 When the online preheating power is 7kW and the online post-weld annealing power is 12kW, the cracks did not tear along the weld during the cupping test and the weld performance was qualified.

[0049] Comparative Example 1 The difference between this comparative example and the embodiment is that the preheating temperature is 250° C., and the preheating temperature here corresponds to a preheating power of 5 kW.

[0050] See also Figure 5 ,When the preheating power is reduced to 5kW, the weld morphology is poor, and cracks are likely to appear along the weld during the ,cupping test.

[0051] Comparative Example 2 The difference between this comparative example and the embodiment is that the preheating temperature is 450° C., and the preheating temperature here corresponds to a preheating power of 9 kW.

[0052] See also Figure 6 ,When the preheating power is increased to 9kW, the weld morphology is not good, and cracks are likely to appear along the weld during the cupping test.

[0053] Comparative Example 3 The difference between this comparative example and the embodiment is that the post-weld heat treatment temperature is 650° C., and the post-weld heat treatment temperature here corresponds to a post-weld heat treatment power of 10 kW.

[0054] See also Figure 7 ,When the post-weld heat treatment power is reduced to 10kW, cracks will appear along the weld during the cupping test, as shown in the figure.

[0055] Comparative Example 4 The difference between this comparative example and the embodiment is that the post-weld heat treatment temperature is 850° C., and the post-weld heat treatment temperature here corresponds to a post-weld heat treatment power of 15 kW.

[0056] See also Figure 8 When the post-weld heat treatment power is increased to 15kW, cracks are likely to appear along the weld during the cupping test.

[0057] In summary, the present invention utilizes a combined process of laser arc hybrid welding, preheating, and post-weld heat treatment to weld hot-rolled high-grade silicon steel, effectively improving the quality of welded joints. The resulting welded joints exhibit excellent toughness and are less prone to breakage. This method is simple, easy to operate, and offers low production costs.

[0058] In addition, those skilled in the art should understand that, although there are many problems in the prior art, each embodiment or technical solution of the present invention may be improved in only one or several aspects, without having to simultaneously solve all the technical problems listed in the prior art or background art. Those skilled in the art should understand that any content not mentioned in a claim should not be construed as limiting the claim.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A laser arc hybrid welding method for high-grade silicon steel, characterized in that: The following steps are involved: Clamp the second steel plate to be welded; Shearing the welding ends of the two steel plates to be welded respectively; Splicing the two sheared steel plates to be welded; The two steel plates to be welded are preheated, laser arc hybrid welded, and heat treated.

2. The laser arc hybrid welding method for high-grade silicon steel according to claim 1, characterized in that: The thicknesses of the steel plates to be welded are h1 and h2 respectively; wherein, h1≤h2, h2-h1≤0.8mm, and h2≤1.3h1.

3. The laser arc hybrid welding method for high-grade silicon steel according to claim 1, characterized in that: The preheating is online preheating; the preheating temperature is above 300° C. and below 400° C.

4. The laser arc hybrid welding method for high-grade silicon steel according to claim 1, characterized in that: The heat treatment is an online heat treatment; the temperature of the heat treatment is above 700° C. and below 800° C.

5. The laser arc hybrid welding method for high-grade silicon steel according to claim 1, characterized in that: The distance between the laser and the welding wire in the laser arc hybrid welding is greater than 2 mm and less than 5 mm.

6. The laser arc hybrid welding method for high-grade silicon steel according to claim 1, characterized in that:

2. The gap between the welded steel plates after shearing and butting is greater than 0.2 mm and less than 0.3 mm.

7. The laser arc hybrid welding method for high-grade silicon steel according to claim 1, characterized in that: The laser arc hybrid welding is a single-sided welding method for welding the inter-plate gap between the two steel strips.

8. The laser arc hybrid welding method for high-grade silicon steel according to claim 1, characterized in that: The laser arc hybrid welding is performed by a laser arc hybrid welding head; Induction heating coils are respectively arranged in front of and behind the laser arc hybrid welding head along the extending direction of the weld to perform preheating and heat treatment.

9. The laser arc hybrid welding method for high-grade silicon steel according to claim 1, characterized in that: The laser arc hybrid welding adopts a single-sided welding method to weld the gap between two steel strips to be welded.

10. The laser arc hybrid welding method for high-grade silicon steel according to claim 1, characterized in that: When welding, blow shielding gas toward the welding part; The shielding gas blown toward the front of the weld is a mixed shielding gas; The shielding gas blown to the back of the weld is a single-component shielding gas; Preferably, the mixed protective gas consists of argon and 18% carbon dioxide; Preferably, the flow rate of the mixed protective gas is greater than 25 L / min and less than 30 L / min; Preferably, the pressure of the mixed protective gas is above 0.4 MPa and below 0.6 MPa; Preferably, the single-component protective gas is argon; Preferably, the flow rate of the single-component protective gas is greater than 8 L / min and less than 15 L / min; Preferably, the pressure of the single-component protective gas is greater than 0.4 MPa and less than 0.6 MPa.

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