A welding material for 1500MPa deep-sea steel with a thickness greater than 30mm and its welding method

Abstract

This invention relates to a welding material for 1500MPa deep-sea steel with a thickness greater than 30mm and a welding method thereof. The welding wire comprises the following components and mass percentages: C: 0.08%–0.13%, Mn: 1.2%–1.6%, Si: 0.3%–0.6%, S≤0.002%, P≤0.005%, Ni: 4.5%–8.5%, Co: 5%–11%, Mo: 0.1%–0.3%, Cr: 0.1%–0.3%, Ti: 0.05%–0.08%, with the remainder being Fe and unavoidable impurities. The welding method includes: bevel design, bevel processing, and confirmation of the assembly gap of the weld joint based on the steel plate thickness; welding, during which high-pressure gas is used to cool the weld surface online; after completing one weld, monitoring the weld temperature until it reaches the preset value, and then starting laser remelting; after the weld undergoes laser remelting, monitoring the weld temperature until it reaches the preset value, and then starting the next welding operation; after completing one weld, welding continues according to the above process until the entire welding operation is completed.

Description

Technical Field

[0001] This invention relates to the field of metal material welding technology, and more particularly to a welding material for 1500MPa deep-sea steel with a thickness greater than 30mm and a welding method thereof. Background Technology

[0002] In recent years, global economic development has led to a surge in human demand for energy, prompting energy exploration to extend into the open ocean and deep sea. Generally, the marine engineering field defines the waters below 300 meters above sea level as the "deep sea," while the international marine science community defines it as the area below the permanent thermocline at a depth of 1000 meters. If 1000 meters is used as the boundary, the deep sea occupies three-quarters of the total ocean volume. Deep-sea ultra-high-strength steel is a key basic material for future deep-sea industrial development. Existing deep-sea titanium alloy structures often employ vacuum electron beam welding, resulting in huge equipment costs and limited welding methods. Furthermore, titanium alloys are expensive and have poor processing capabilities, making the manufacturing cost of titanium alloy deep-sea equipment extremely high, thus limiting its large-scale application. High-strength steel possesses advantages such as high strength, low cost, and good processing performance. Among them, Co-Ni series ultra-high-strength steel exhibits ultra-high strength, excellent fracture toughness, and good weldability, showing promising application prospects in the field of deep-sea equipment. Therefore, developing welding materials and processes to support Co-Ni series ultra-high strength steel for deep-sea equipment is of great significance for expanding the development and utilization of deep-sea energy.

[0003] Regarding the development of welding materials and processes for ultra-high strength steel, Chinese patent application CN 117259990 A discloses a laser-arc composite welding method for tempered ultra-high strength steel plates with a yield strength of 1400MPa; Chinese patent application CN 116100130 A discloses a welding method for ultra-high strength steel plates with a yield strength of 1400MPa; and Chinese patent application CN 105598596 A discloses a non-preheating combined welding method for 1200MPa high strength steel. The aforementioned patents primarily use 90KG grade low-strength welding wire for welding, and the strength of the joints does not reach the strength of the base material, significantly impacting the load-bearing capacity and safety of the high-strength steel welded structures.

[0004] Chinese patent application CN 108637524 A discloses a flux-cored welding wire for welding 1500MPa grade ultra-high strength alloy steel, and Chinese patent application CN 105234587 A discloses a solid core welding wire without copper plating for gas shielded welding of 1500MPa grade ultra-high strength steel. The welding material compositions disclosed in these patents primarily focus on the 1500MPa strength index, without considering the comprehensive performance of 1500MPa ultra-high strength steel under the special working conditions of deep sea applications. High-strength steel welded structures operating in the high-pressure, oxygen-free, low-temperature, or locally high-temperature (400℃) environments of the deep sea place even higher demands on their strength and low-temperature toughness.

[0005] Welding 1500MPa deep-sea steel presents several challenges: 1) Hydrogen (H) from the marine environment can enter the deep-sea steel structure. If the H content in the weld is high, the combined effect of H inside the weld and H in the deep sea reduces the material's plasticity, leading to hydrogen embrittlement. 2) When welding thicker steel plates (≥30mm), large-angle beveling and multi-layer, multi-pass welding are often required, resulting in long welding cycles, difficult interlayer cleaning, and high labor intensity. The poor fluidity of high-strength welding materials can easily lead to poor weld formation and a high rework rate. 3) Ultra-high-strength steel has a high carbon equivalent and high hardenability, often requiring pre- and post-weld heat treatment to reduce welding stress and welding cracking tendency, increasing welding costs. Summary of the Invention

[0006] To address the aforementioned technical problems, a welding material for 1500MPa deep-sea steel with a thickness greater than 30mm and its welding method are provided. This method involves designing and matching a 1500MPa deep-sea steel solid core welding wire, and employing a narrow-gap hot-wire arc welding method combined with laser remelting. This ensures good weld formation, improves welding efficiency, and better eliminates moisture adsorbed on the welding wire surface, reducing the source of hydrogen in the weld and minimizing the superposition of hydrogen within the weld and in the deep sea, thereby reducing the hydrogen embrittlement sensitivity of the weld. The weld metal deposited by this wire has a tensile strength >1500MPa, a yield strength >1380MPa, an elongation >12%, and an impact energy >75J at -60℃, ensuring excellent comprehensive performance of the weld.

[0007] The technical means employed in this invention are as follows:

[0008] A 1500MPa deep-sea steel welding material with a thickness greater than 30mm has the following composition and mass percentage: C: 0.08%–0.13%, Mn: 1.2%–1.6%, Si: 0.3%–0.6%, S≤0.002%, P≤0.005%, Ni: 4.5%–8.5%, Co: 5%–11%, Mo: 0.1%–0.3%, Cr: 0.1%–0.3%, Ti: 0.05%–0.08%, with the remainder being Fe and unavoidable impurities.

[0009] Further, as a more preferred embodiment, the composition and mass percentage are as follows: C: 0.09%–0.12%, Mn: 1.25%–1.35%, Si: 0.35%–0.55%, S≤0.002%, P≤0.005%, Ni: 5%–8%, Co: 6.5%–9%, ​​Mo: 0.15%–0.3%, Cr: 0.15%–0.3%, Ti: 0.06%–0.08%, with the remainder being Fe and unavoidable impurities.

[0010] From the perspective of alloy composition, the welding wire deposited metal used in this invention is a high-Co-Ni secondary hardening steel. The selection principle and content design reasons are as follows:

[0011] C: The C content ensures high strength of the weld metal. A C content higher than 0.2% will severely deteriorate the weldability of the weld metal, while a C content lower than 0.07% will not guarantee a weld metal strength greater than 1000 MPa. Maintaining a certain C content and a specific Cr / Mo ratio in the weld ensures that fine M2C-type carbides precipitate in the weld metal during subsequent heating, achieving secondary strengthening. Considering all factors, the preferred C content in this invention is 0.08%–0.13%; Mo: 0.1%–0.3%; Cr: 0.1%–0.3%.

[0012] Ni: High Ni content can improve the hardenability of steel, lower the ductile-brittle transition temperature and cleavage fracture tendency of the weld metal, and improve the toughness of the weld metal. Adding Ni can improve the strength of steel welds without significantly reducing their toughness. A Ni content greater than 3.5% can ensure that the weld metal has good impact toughness at -40℃. Considering other elements, the preferred Ni content in this invention is 4.5%-8.5%.

[0013] Co: High Co content can delay the recovery of dislocation substructures in martensite, ensuring the formation of fine and dispersed alloy carbides at dislocation sites; Co can increase the Ms temperature, and a high Co content (greater than 5%) can inhibit the formation of retained austenite, making it easier for the weld to form a fully martensitic structure, resulting in ultra-high hardness and good comprehensive mechanical properties. Considering other elements, the preferred Co content in this invention is 5% to 11%.

[0014] The combined deoxidation using Si and Mn produces MnO·SiO2, which has a low melting point (approximately 1270℃) and low density. This allows it to agglomerate into large slag masses in the molten pool and float to the surface, achieving a good deoxidation effect. Furthermore, Mn combines with S to form MnS, which reduces the tendency for S-induced hot cracking. To ensure effective deoxidation of the weld, the Si content should be no less than 0.3%, but a Si content greater than 0.6% will cause solution hardening and an increase in the number of secondary phases, leading to weld brittleness. This invention preferably uses a Si content of 0.3%–0.6% and an Mn / Si ratio in the range of 2.3–3.8, resulting in welds with good overall performance.

[0015] Mo: Mo has a significant impact on weld strength, but a Mo content greater than 0.5% is detrimental to the weld elongation and impact performance. When the Mn content is low, the low Mo content can balance the weld strength and toughness. Considering other elements, the preferred Mo content in this invention is 0.1% to 0.3%.

[0016] Ti: Trace amounts of Ti easily form TiO inclusions during welding, promoting nucleation within austenite grains and improving the toughness of the weld metal. Ti content greater than 0.1% promotes the formation of hard phases such as bainite and MA components in the weld microstructure, deteriorating the weld toughness. Considering other elements, the preferred Ti content in this invention is 0.05%-0.08%.

[0017] The present invention also discloses a welding method using the above-mentioned welding materials, comprising the following steps:

[0018] Step 1: Design the bevel for each steel to be welded, process the bevel, and clean the oil and impurities from the bevel.

[0019] Step 2: Determine the assembly gap of the welded joint based on the steel plate thickness;

[0020] Step 3: Set welding process parameters, introduce welding shielding gas, adjust the high-pressure gas injection position and flow rate, and carry out welding. During the welding process, the high-pressure gas is sprayed onto the surface of the weld to cool it. After completing one weld, monitor the weld temperature until it reaches the preset value, and then start laser remelting.

[0021] Step 4: After the weld is laser remelted, monitor the weld temperature until it reaches the preset value, then proceed with the next welding operation. After one weld is completed, continue welding according to the above process until the entire welding operation is finished.

[0022] Furthermore, in step 1, the bevel angle α is 5° to 20°.

[0023] Further, in step 1, the bevel is cleaned by grinding with a grinding wheel to remove iron oxide scale and iron filings, and the surface rust and oil stains within 20-40mm on both sides of the bevel are cleaned.

[0024] Furthermore, in step 2, the assembly (root) gap D of the welded joint is controlled according to the plate thickness T. When T≤50mm, D=5~13mm, and when 50mm<T, D=13~18mm.

[0025] Furthermore, in step 3, the welding process parameters include: welding shielding gas flow rate of 20-25 L / min, hot wire current of 20-50 A, welding current of 250-350 A, welding voltage of 15-20 V, and welding torch moving speed of 300-500 mm / min.

[0026] Furthermore, in step 3, while starting welding, the adjusting wheel behind the welding torch is adjusted so that high-pressure gas is blown onto the weld surface. The flow rate of the high-pressure gas is 100-300 L / min, and the pressure of the high-pressure gas is 0.1-1 MPa.

[0027] Furthermore, in step 4, when the temperature of the weld reaches 100-160°C, the reciprocating sweeping laser remelting process begins; in step 5, after the weld undergoes laser remelting, when the temperature of the weld is monitored to be 100-160°C, the next welding operation begins.

[0028] Furthermore, the laser remelting processing parameters include: the laser focusing mode is defocused, the laser power is 1.5 to 3 kW, and the laser scanning speed is 3 to 8 m / s.

[0029] Furthermore, the composition and mass percentage of the 1500MPa grade deep-sea steel to be welded are as follows: C: 0.1%–0.5%, Mn: 0.2%–1.0%, Si: 0.1%–0.8%, S≤0.002%, P≤0.005%, Ni: 6%–15%, Co: 6%–15%, Mo: 0.5%–2.5%, Cr: 1%–5%, Ti: 0.02%–0.30%, with the remainder being Fe and unavoidable impurities.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] 1. This invention is designed for 1500MPa deep-sea steel. The welding wire used in this invention adopts the design principle of high Co-Ni secondary hardening steel weld metal, which can control the low C content to ensure that the weld microstructure is high-toughness lath martensite. Therefore, pre-weld heat treatment is not required, and the weld still has excellent crack resistance. Furthermore, through synchronous online cooling treatment during welding, the residual austenite in the weld is transformed into martensite as completely as possible to obtain a full martensitic microstructure, ensuring that the weld has excellent comprehensive performance.

[0032] 2. This invention controls the assembly gap D of the welded joint based on the plate thickness T, employing a hot-wire narrow-gap welding process. The welding wire fed into the molten pool carries a low-voltage current, which effectively preheats the wire, better eliminating moisture adsorbed on the wire surface and reducing the source of hydrogen in the weld. Therefore, in marine environments (high-H environments), welds with low H content have lower susceptibility to hydrogen-induced cracking, eliminating the need for pre-weld heat treatment. Furthermore, the narrow gap significantly reduces the filler metal in the weld, improving welding efficiency.

[0033] 3. During the welding process of this invention, the high-pressure gas behind the welding torch can rapidly increase the cooling rate of the weld. The baffle prevents the high-pressure gas from affecting the arc combustion, effectively subjecting the weld to online quenching heat treatment, thus improving its strength. The online heat treatment process formed by spraying high-pressure gas during welding can eliminate the need for lengthy post-weld heat treatment, reducing welding costs.

[0034] 4. In this invention, the weld surface undergoes laser remelting to form a remelted layer, which develops a fine-grained structure. For multi-layer, multi-pass welding of thick plates, the welding heat flow and heat dissipation direction can lead to significant orientation characteristics in the coarse dendrites within the weld, easily causing alloy element segregation and cracking. Furthermore, the heat-affected zone during welding can coarsen the grain structure of the previous weld pass, resulting in a deterioration of the overall weld performance. The fine equiaxed grain structure of the remelted layer after laser treatment hinders the growth of coarse dendrites between passes in the weld. Laser remelting also provides a short-term tempering treatment to the weld, promoting the precipitation of fine M2C carbides in the remelted layer and improving the strength and toughness of the weld metal. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a frontal schematic diagram of the welding process of the present invention.

[0037] Figure 2 This is a side view of the welding process of the present invention.

[0038] Figure 3 This is a schematic diagram of laser remelting according to the present invention.

[0039] Figure 4 This is a schematic diagram of the connector assembly of the present invention.

[0040] Figure 5 This is a macroscopic photograph of the cross-section of the 80mm thick joint of the present invention.

[0041] Figure 6 This is a micro-area scanning image of the weld seam of the present invention.

[0042] In the diagram: 1-base material; 2-liner plate; 31-motor; 32-drive gear; 33-driven gear; 34-bent tungsten electrode; 35-gun body; 4-weld; 5-wire guide tube; 6-hot wire; 7-molten pool; 8-baffle; 9-adjusting wheel; 10-nozzle; 11-high-pressure gas; 12-weld plane; 13-laser head; 14-laser remelting position. Detailed Implementation

[0043] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0046] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0047] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0048] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0049] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0050] A 1500MPa deep-sea steel welding material with a thickness greater than 30mm has the following composition and mass percentage: C: 0.08%–0.13%, Mn: 1.2%–1.6%, Si: 0.3%–0.6%, S≤0.002%, P≤0.005%, Ni: 4.5%–8.5%, Co: 5%–11%, Mo: 0.1%–0.3%, Cr: 0.1%–0.3%, Ti: 0.05%–0.08%, with the remainder being Fe and unavoidable impurities.

[0051] Furthermore, as a more preferred embodiment, the composition and mass percentage of the steel welding material are as follows: C: 0.09%–0.12%, Mn: 1.25%–1.35%, Si: 0.3%–0.6%, S≤0.002%, P≤0.005%, Ni: 4.5%–8.5%, Co: 6.5%–9%, ​​Mo: 0.1%–0.3%, Cr: 0.1%–0.3%, Ti: 0.05%–0.08%, with the remainder being Fe and unavoidable impurities.

[0052] like Figures 1-4 As shown, the present invention also discloses a welding method using the above-mentioned welding material, comprising the following steps:

[0053] Step 1: Design the bevel for the steel base material 1 to be welded, process the bevel, and clean the oil and impurities at the bevel.

[0054] Step 2: Confirm the assembly gap of the welded joint based on the thickness of the steel plate; a liner plate 2 of preset length and thickness is set under the two base materials;

[0055] Step 3: Set welding process parameters, introduce welding shielding gas, and begin welding. Specifically, use 99.99% argon as the shielding gas. Turn on the motor 31 that controls the oscillation of the bent tungsten electrode 34 of the welding torch. The motor 31 drives the drive gear 32 and the driven gear 33, which in turn drives the oscillation of the bent tungsten electrode 34 at the end of the torch body 35, causing the heated tungsten electrode to form a fan-shaped arc micro-region. Adjust the position of the wire guide tube 5, and the dry extension of the hot wire 6 is 15-25mm. After being heated, the wire enters the molten pool 7 formed by the arc, reducing the H content in the weld. Simultaneously with the start of welding, adjust the adjusting wheel at the rear of the welding torch to direct high-pressure gas towards the weld surface. The online heat treatment process formed by spraying high-pressure gas during welding can eliminate the need for a lengthy post-weld heat treatment process, reducing welding costs.

[0056] Step 4: After completing one weld seam 4, shut off the high-pressure gas and monitor the weld seam temperature until it reaches the preset value, then begin laser remelting treatment. The laser remelts the weld seam surface, forming a remelted zone on the weld seam surface, improving the surface roughness of the weld seam, removing impurities from the weld seam surface, making the weld seam cleaner, and also eliminating the need for weld bead cleaning. In addition, the thermal effect of the laser will also perform short-term heat treatment on the micro-regions below the surface of the weld seam, forming a heat treatment effect similar to tempering, promoting the precipitation of fine precipitates in the weld seam, and improving the comprehensive mechanical properties of the weld seam.

[0057] Step 5: After the weld is laser remelted, monitor the weld temperature until it reaches the preset value (see relevant embodiments for details). Then proceed with the next welding operation. After one weld is completed, continue welding according to the above process until the entire welding operation is completed.

[0058] Furthermore, in step 1, the bevel angle α is 5° to 20°.

[0059] Further, in step 1, the bevel is cleaned by grinding with a grinding wheel to remove iron oxide scale and iron filings, and the surface rust and oil stains within 25±1mm on both sides of the bevel are cleaned.

[0060] Furthermore, in step 2, the assembly gap D of the welded joint is controlled according to the plate thickness T. When T≤50mm, D=5mm~12mm, and when 50mm<T, D=13~18mm.

[0061] Furthermore, in step 3, the welding process parameters include: gas flow rate of 20-25 L / min, hot wire current of 20-50 A, welding current of 250-350 A, welding voltage of 15-20 V, and welding torch moving speed of 300-500 mm / min.

[0062] Furthermore, in step 3, simultaneously with the start of welding, the adjusting wheel 9 behind the welding torch is adjusted so that high-pressure gas (compressed air) 11 is blown onto the weld surface 12 through the nozzle 10. The baffle 8 is adjusted to ensure that the high-pressure airflow does not affect the molten arc pool. The flow rate of the high-pressure gas is 100–300 L / min, and the pressure is 0.1–1 MPa. The deposited metal of the weld undergoes rapid cooling, achieving a heat treatment effect similar to quenching.

[0063] Furthermore, in step 4, when the temperature of the weld reaches 100-160°C, the reciprocating sweeping laser remelting process 14 is started; in step 5, after the weld undergoes laser remelting, when the temperature of the weld is monitored to be 100-160°C, the next welding operation is started.

[0064] Furthermore, the laser remelting processing parameters include: the laser focusing mode is defocused, the laser power of the laser head 13 is 1.5 to 3 kW, and the laser scanning speed is 3 to 8 m / s.

[0065] Furthermore, the composition and mass percentage of the 1500MPa grade deep-sea steel to be welded are as follows: C: 0.1%–0.5%, Mn: 0.2%–1.0%, Si: 0.1%–0.8%, S≤0.002%, P≤0.005%, Ni: 6%–15%, Co: 6%–15%, Mo: 0.5%–2.5%, Cr: 1%–5%, Ti: 0.02%–0.30%, with the remainder being Fe and unavoidable impurities.

[0066] Example 1

[0067] In this embodiment, 1500MPa deep-sea steel with a plate thickness of 50mm is welded. The alloy composition and mass percentage of the base material are as follows: C: 0.2%, Mn: 0.25%, Si: 0.2%, S≤0.002%, P≤0.005%, Ni: 8%, Co: 9%, Mo: 0.65%, Cr: 1.5%, Ti: 0.06%, with the remainder being Fe and unavoidable impurities.

[0068] 1) Design the composition of the welding wire deposited metal: C: 0.11%; Mn: 1.3%; Si: 0.35%; Mn / Si = 3.7, S ≤ 0.002%; P ≤ 0.005%; Ni: 5.5%; Co: 6.5%; Mo: 0.15%; Cr: 0.15%; Ti: 0.06%; the remainder is Fe and unavoidable impurities.

[0069] 2) Beveling and pre-welding treatment: The beveling angle α is 8°; use a grinding wheel to grind and clean the beveling, remove iron oxide scale and iron filings, and clean the surface rust and oil within 25mm on both sides of the beveling; control the assembly gap D of the welded joint according to the plate thickness T, D = 8mm.

[0070] 3) Set welding parameters and begin welding. Use 99.99% argon as the shielding gas, with a flow rate of 20 L / min and a hot wire current of 25 A. The hot wire current effectively preheats the welding wire, better eliminating moisture adsorbed on the wire surface and reducing the source of hydrogen in the weld. In marine environments (high-H environments), welds with low H content have lower susceptibility to hydrogen-induced cracking. The welding current is 270 A, the welding voltage is 17 V, and the welding torch movement speed is 350 mm / min. Turn on the motor controlling the bending and oscillation of the tungsten electrode in the welding torch, causing the heated tungsten electrode to form a fan-shaped arc micro-region. Simultaneously with the start of welding, adjust the adjusting wheel at the rear of the welding torch to direct high-pressure gas onto the weld surface. The gas flow rate is 150 L / min, and the gas pressure is 0.6 MPa.

[0071] 4) After completing a weld, when the temperature of the weld is monitored to be 110℃, laser remelting is started. The laser focusing mode is defocused, the laser power is adjusted to 1.8kW, and the laser scanning speed is 3.5m / s to complete the remelting sweeping of the entire weld surface.

[0072] 5) After laser remelting of the weld, when the weld temperature reaches 110℃, begin the next welding operation. Once one weld is completed, continue welding according to the above process until the entire welding operation is finished. The tensile strength of the weld metal deposited by this welding wire is 1535MPa, the yield strength is 1396MPa, the elongation is 13%, and the impact energy at -60℃ is 85J.

[0073] Example 2

[0074] In this embodiment, 1500MPa deep-sea steel with a plate thickness of 42mm is welded. The alloy composition and mass percentage of the base material are as follows: C: 0.2%, Mn: 0.25%, Si: 0.2%, S≤0.002%, P≤0.005%, Ni: 8%, Co: 9%, Mo: 0.65%, Cr: 1.5%, Ti: 0.06%, with the remainder being Fe and unavoidable impurities.

[0075] 1) Design the composition of the weld metal deposited on the welding wire: C: 0.12%; Mn: 1.3%; Si: 0.35%; Mn / Si = 3.7.

[0076] S≤0.002%; P≤0.005%; Ni: 8%; Co: 9%; Mo: 0.15%; Cr: 0.15%;

[0077] Ti: 0.06%; the remainder is Fe and unavoidable impurities.

[0078] 2) Beveling and pre-welding treatment: The beveling angle α is 6°; use a grinding wheel to grind and clean the beveling, remove iron oxide scale and iron filings, and clean the surface rust and oil within 25mm on both sides of the beveling; control the assembly gap D of the welding joint according to the plate thickness T, D = 6mm.

[0079] 3) Set the welding parameters and begin welding. Use 99.99% argon as the shielding gas, with a gas flow rate of 20 L / min, a hot wire current of 20 A, a welding current of 260 A, a welding voltage of 16 V, and a welding torch movement speed of 400 mm / min. Turn on the motor that controls the bending and oscillation of the tungsten electrode in the welding torch, so that the heated tungsten electrode forms a fan-shaped arc micro-area. Simultaneously with the start of welding, adjust the adjusting wheel at the rear of the welding torch to direct high-pressure gas onto the weld surface. The gas flow rate is 200 L / min, and the gas pressure is 0.4 MPa.

[0080] 4) After completing a weld, when the temperature of the weld is monitored to be 110℃, laser remelting is started. The laser focusing mode is defocused, the laser power is adjusted to 1.5kW, and the laser scanning speed is 3.5m / s to complete the remelting of the entire weld surface.

[0081] 5) After laser remelting of the weld, when the weld temperature reaches 110℃, begin the next welding operation. Once one weld is completed, continue welding according to the above process until the entire welding operation is finished. The tensile strength of the weld metal deposited by this welding wire is 1549MPa, the yield strength is 1410MPa, the elongation is 13.5%, and the impact energy at -60℃ is 92J.

[0082] Example 3

[0083] In this embodiment, 1500MPa deep-sea steel with a plate thickness of 35mm is welded. The alloy composition and mass percentage of the base material are as follows: C: 0.2%, Mn: 0.25%, Si: 0.2%, S≤0.002%, P≤0.005%, Ni: 7.5%, Co: 8%, Mo: 0.65%, Cr: 1.5%, Ti: 0.06%, with the remainder being Fe and unavoidable impurities.

[0084] 1) Design the composition of the welding wire deposited metal: C: 0.11%; Mn: 1.25%; Si: 0.35%; Mn / Si = 3.6, S ≤ 0.002%; P ≤ 0.005%; Ni: 8%; Co: 8%; Mo: 0.15%; Cr: 0.15%; Ti: 0.06%; the remainder is Fe and unavoidable impurities.

[0085] 2) Beveling and pre-welding treatment: The beveling angle α is 5°; use a grinding wheel to grind and clean the beveling, remove iron oxide scale and iron filings, and clean the surface rust and oil within 25mm on both sides of the beveling; control the assembly gap D of the welded joint according to the plate thickness T, D = 5mm.

[0086] 3) Set the welding parameters and begin welding. Use 99.99% argon as the shielding gas, with a gas flow rate of 20 L / min, a hot wire current of 22 A, a welding current of 265 A, a welding voltage of 15 V, and a welding torch movement speed of 360 mm / min. Turn on the motor that controls the bending and oscillation of the tungsten electrode in the welding torch, so that the heated tungsten electrode forms a fan-shaped arc micro-area. Simultaneously with the start of welding, adjust the adjusting wheel at the rear of the welding torch to direct high-pressure gas onto the weld surface. The gas flow rate is 200 L / min, and the gas pressure is 0.4 MPa.

[0087] 4) After completing a weld, when the temperature of the weld is monitored to be 120℃, laser remelting is started. The laser focusing mode is defocused, the laser power is adjusted to 1.6kW, and the laser scanning speed is 3.5m / s to complete the remelting and sweeping remelting of the entire weld surface.

[0088] 5) After laser scanning remelting of the weld, when the weld temperature reaches 120℃, begin the next welding operation. Once one weld is completed, continue welding according to the above process until the entire welding operation is finished. The tensile strength of the weld metal deposited by this welding wire is 1533MPa, the yield strength is 1405MPa, the elongation is 13.5%, and the impact energy at -60℃ is 96J.

[0089] Example 4

[0090] In this embodiment, 1500MPa deep-sea steel with a plate thickness of 60mm is welded. The alloy composition and mass percentage of the base material are as follows: C: 0.23%, Mn: 0.35%, Si: 0.25%, S≤0.002%, P≤0.005%, Ni: 7.5%, Co: 10%, Mo: 0.65%, Cr: 1.5%, Ti: 0.06%, with the remainder being Fe and unavoidable impurities.

[0091] 1) Design the composition of the welding wire deposited metal: C: 0.1%; Mn: 1.35%; Si: 0.40%; Mn / Si = 3.4, S ≤ 0.002%; P ≤ 0.005%; Ni: 5.5%; Co: 7%; Mo: 0.30%; Cr: 0.25%; Ti: 0.08%; the remainder is Fe and unavoidable impurities.

[0092] 2) Beveling and pre-welding treatment: The beveling angle α is 10°; use a grinding wheel to grind and clean the beveling, remove iron oxide scale and iron filings, and clean the surface rust and oil within 30mm on both sides of the beveling; control the assembly gap D of the welded joint according to the plate thickness T, D = 15mm.

[0093] 3) Set the welding parameters and begin welding. Use 99.99% argon as the shielding gas, with a gas flow rate of 25 L / min, a hot wire current of 30 A, a welding current of 290 A, a welding voltage of 18 V, and a welding torch movement speed of 400 mm / min. Turn on the motor that controls the bending and oscillation of the tungsten electrode in the welding torch, so that the heated tungsten electrode forms a fan-shaped arc micro-area. Simultaneously with the start of welding, adjust the adjusting wheel at the rear of the welding torch to direct high-pressure gas onto the weld surface. The gas flow rate is 200 L / min, and the high-pressure gas pressure is 1 MPa.

[0094] 4) After completing a weld, when the temperature of the weld is monitored to be 130℃, laser remelting is started. The laser focusing mode is defocused, the laser power is adjusted to 2.5kW, and the laser scanning speed is 3m / s to complete the remelting of the entire weld surface.

[0095] 5) After laser remelting of the weld, when the weld temperature reaches 130℃, begin the next welding operation. Once one weld is completed, continue welding according to the above process until the entire welding operation is finished. The tensile strength of the weld metal deposited by this welding wire is 1547MPa, the yield strength is 1403MPa, the elongation is 12.5%, and the impact energy at -60℃ is 88J.

[0096] Example 5

[0097] In this embodiment, 1500MPa deep-sea steel with a plate thickness of 65mm is welded. The alloy composition and mass percentage of the base material are as follows: C: 0.22%, Mn: 0.35%, Si: 0.35%, S≤0.002%, P≤0.005%, Ni: 7%, Co: 7.5%, Mo: 0.65%, Cr: 2.0%, Ti: 0.05%, with the remainder being Fe and unavoidable impurities.

[0098] 1) Design the composition of the welding wire deposited metal: C: 0.09%; Mn: 1.27%; Si: 0.45%; Mn / Si = 2.8, S ≤ 0.002%; P ≤ 0.005%; Ni: 6.5%; Co: 7.5%; Mo: 0.18%; Cr: 0.30%; Ti: 0.06%; the remainder is Fe and unavoidable impurities.

[0099] 2) Beveling and pre-welding treatment: The beveling angle α is 11°; use a grinding wheel to grind and clean the beveling, remove iron oxide scale and iron filings, and clean the surface rust and oil within 40mm on both sides of the beveling; control the assembly gap D of the welding joint according to the plate thickness T, D = 15mm.

[0100] 3) Set the welding parameters and begin welding. Use 99.99% argon as the shielding gas, with a gas flow rate of 22 L / min, a hot wire current of 30 A, a welding current of 290 A, a welding voltage of 18 V, and a welding torch movement speed of 300 mm / min. Turn on the motor that controls the bending and oscillation of the tungsten electrode in the welding torch, so that the heated tungsten electrode forms a fan-shaped arc micro-area. Simultaneously with the start of welding, adjust the adjusting wheel at the rear of the welding torch to direct high-pressure gas onto the weld surface. The gas flow rate is 250 L / min, and the gas pressure is 0.5 MPa.

[0101] 4) After completing a weld, when the temperature of the weld is monitored to be 110℃, laser remelting is started. The laser focusing mode is defocused, the laser power is adjusted to 2.5kW, and the laser scanning speed is 3.5m / s to complete the remelting of the entire weld surface.

[0102] 5) After laser remelting of the weld, when the weld temperature reaches 110℃, begin the next welding operation. Once one weld is completed, continue welding according to the above process until the entire welding operation is finished. The tensile strength of the weld metal deposited by this welding wire is 1526MPa, the yield strength is 1378MPa, the elongation is 13%, and the impact energy at -60℃ is 85J.

[0103] Example 6

[0104] In this embodiment, 1500MPa deep-sea steel with a plate thickness of 80mm was welded. The alloy composition and mass percentage of the base material are as follows: C: 0.2%, Mn: 0.25%, Si: 0.2%, S≤0.002%, P≤0.005%, Ni: 8%, Co: 9%, Mo: 0.65%, Cr: 1.8%, Ti: 0.06%, with the remainder being Fe and unavoidable impurities. Macroscopic photographs and weld micro-area scanning photographs of this embodiment are shown below. Figure 5 , Figure 6 As shown.

[0105] 1) Design the composition of the welding wire deposited metal: C: 0.09%; Mn: 1.25%; Si: 0.55%; Mn / Si = 2.3, S ≤ 0.002%; P ≤ 0.005%; Ni: 6.5%; Co: 8.5%; Mo: 0.15%; Cr: 0.30%; Ti: 0.07%; the remainder is Fe and unavoidable impurities.

[0106] 2) Beveling and pre-welding treatment: The beveling angle α is 13°; use a grinding wheel to grind and clean the beveling, remove iron oxide scale and iron filings, and clean the surface rust and oil within 40mm on both sides of the beveling; control the assembly gap D of the welding joint according to the plate thickness T, D = 16mm.

[0107] 3) Set the welding parameters and begin welding. Use 99.99% argon as the shielding gas, with a gas flow rate of 25 L / min, a hot wire current of 32 A, a welding current of 300 A, a welding voltage of 19 V, and a welding torch movement speed of 350 mm / min. Turn on the motor that controls the bending and oscillation of the tungsten electrode in the welding torch, so that the heated tungsten electrode forms a fan-shaped arc micro-area. Simultaneously with the start of welding, adjust the adjusting wheel at the rear of the welding torch to direct high-pressure gas onto the weld surface. The gas flow rate is 250 L / min, and the gas pressure is 0.5 MPa.

[0108] 4) After completing a weld, when the temperature of the weld is monitored to be 130℃, laser remelting is started. The laser focusing mode is defocused, the laser power is adjusted to 2.8kW, and the laser scanning speed is 3.7m / s to complete the remelting of the entire weld surface.

[0109] 5) After laser remelting of the weld, when the weld temperature reaches 130℃, begin the next welding operation. Once one weld is completed, continue welding according to the above process until the entire welding operation is finished. The tensile strength of the weld metal deposited by this welding wire is 1516MPa, the yield strength is 1398MPa, the elongation is 12.8%, and the impact energy at -60℃ is 81J.

[0110] 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 1500MPa deep-sea steel welding material with a thickness greater than 30mm, characterized in that, The composition and mass percentage are as follows: C: 0.08%–0.13%, Mn: 1.2%–1.6%, Si: 0.3%–0.6%, S≤0.002%, P≤0.005%, Ni: 4.5%–8.5%, Co: 5%–11%, Mo: 0.1%–0.3%, Cr: 0.1%–0.3%, Ti: 0.05%–0.08%, with the remainder being Fe and unavoidable impurities.

2. The 1500MPa deep-sea steel welding material with a thickness greater than 30mm according to claim 1, characterized in that, The composition and mass percentage are as follows: C: 0.09%–0.12%, Mn: 1.25%–1.35%, Si: 0.35%–0.55%, S≤0.002%, P≤0.005%, Ni: 5%–8%, Co: 6.5%–9%, ​​Mo: 0.15%–0.3%, Cr: 0.15%–0.3%, Ti: 0.06%–0.08%, with the remainder being Fe and unavoidable impurities, and Mn / Si = 2.3–3.

8.

3. A welding method using any one of the welding materials of claim 1 or 2, characterized in that, Includes the following steps: Step 1: Design the bevel for each steel to be welded, process the bevel, and clean the oil and impurities from the bevel. Step 2: Determine the assembly gap of the welded joint based on the steel plate thickness; Step 3: Set the welding process parameters, introduce the welding shielding gas, and adjust the high-pressure gas injection position and flow rate to carry out welding. During the welding process, turn on the high-pressure gas to spray and cool the surface of the weld formed by welding. After completing a weld, once the weld temperature reaches the preset value, laser remelting is initiated. Step 4: After the weld is laser remelted, monitor the weld temperature until it reaches the preset value, then proceed with the next welding operation. After one weld is completed, continue welding according to the above process until the entire welding operation is finished.

4. The method according to claim 3, characterized in that, In step 1, the bevel angle α is 5° to 20°.

5. The method according to claim 3, characterized in that, In step 2, the assembly gap D of the welding joint is controlled according to the plate thickness T. When T≤50mm, D=5~13mm, and when 50mm<T, D=13~18mm.

6. The method according to claim 3, characterized in that, In step 3, the welding process parameters include: welding shielding gas flow rate of 20-25 L / min, hot wire current of 20-50 A, welding current of 250-350 A, welding voltage of 15-20 V, and welding torch moving speed of 300-500 mm / min.

7. The method according to claim 3, characterized in that, In step 3, while starting welding, adjust the adjusting wheel behind the welding torch to blow high-pressure gas onto the weld surface. The flow rate of the high-pressure gas is 100-300 L / min, and the pressure of the high-pressure gas is 0.1-1 MPa.

8. The method according to claim 3, characterized in that, In step 4, when the temperature of the weld reaches 100-160℃, the reciprocating sweeping laser remelting process begins; in step 5, after the weld undergoes laser remelting, when the temperature of the weld is monitored to be 100-160℃, the next welding operation begins.

9. The method according to claim 3, characterized in that, The laser remelting process parameters This includes: the laser focusing method is defocused, the laser power is 1.5 to 3 kW, and the laser scanning speed is 3 to 8 m / s.

10. The method according to claim 3, characterized in that, The composition and mass percentage of the 1500MPa grade deep-sea steel to be welded are as follows: C: 0.1%~0.5%, Mn: 0.2%~1.0%, Si: 0.1%~0.8%, S≤0.002%, P≤0.005%, Ni: 6%~15%, Co: 6%~15%, Mo: 0.5%~2.5%, Cr: 1%~5%, Ti: 0.02%~0.30%, with the remainder being Fe and unavoidable impurities.

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