1500MPa deep sea steel welding material with thickness larger than 30mm and welding method of 1500MPa deep sea steel welding material

Abstract

The invention relates to a 1500MPa deep sea steel welding material with the thickness larger than 30mm and a welding method of the 1500MPa deep sea steel welding material. The welding wire is prepared from, by mass, 0.08%-0.13% of C, 1.2%-1.6% of Mn, 0.3%-0.6% of Si, smaller than or equal to 0.002% of S, smaller than or equal to 0.005% of P, 4.5%-8.5% of Ni, 5%-11% of Co, 0.1%-0.3% of Mo, 0.1%-0.3% of Cr, 0.05%-0.08% of Ti and the balance Fe and inevitable impurities. The welding method comprises the steps of designing a groove, machining the groove, and confirming an assembly gap of a welding joint based on the thickness of a steel plate; in the welding process, high-pressure gas cools the surface of a weld joint on line; after one welding seam is completed and the temperature of the welding seam is monitored to reach a preset value, laser remelting treatment is started; and after the welding seam is subjected to laser remelting treatment and the temperature of the welding seam is monitored to reach a preset value, next welding work is carried out, and after one welding seam is welded, welding continues according to the process till the whole welding work is finished.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material welding, and in particular to a 1500MPa deep-sea steel welding material with a thickness greater than 30mm and a welding method thereof. Background Art

[0002] In recent years, the development of the global economy has led to an increasing demand for energy, and human energy development has gradually moved towards the open sea and deep sea. Generally, the marine engineering field calls the sea area below 300m below sea level the "deep sea", while the international marine science community calls the area below the 1000m permanent thermocline the deep sea. If 1000m is used as the boundary, the deep sea accounts for 3 / 4 of the total volume of the ocean. Deep-sea ultra-high-strength steel is the key basic material for the future development of the deep-sea industry. Existing deep-sea titanium alloy structures often use vacuum electron beam welding, which has huge equipment cost investment and limited welding methods. However, titanium alloys are expensive and have poor processing technology. Therefore, the manufacturing cost of titanium alloy deep-sea equipment is very high, which limits the large-scale application of titanium alloy deep-sea equipment. High-strength steel has the advantages of high strength, low cost, and good processing performance. Among them, Co-Ni ultra-high-strength steel has ultra-high strength, excellent fracture toughness and good weldability, and has good application prospects in the field of deep-sea equipment. Therefore, the development of Co-Ni ultra-high strength steel supporting welding materials and welding processes for deep-sea equipment is of great significance for expanding the development and utilization of deep-sea energy.

[0003] Regarding the development of ultra-high strength steel welding materials and processes, Chinese patent CN 117259990 A discloses a laser arc hybrid welding method for quenched and tempered ultra-high strength steel plates with a yield strength of 1400MPa, Chinese patent CN 116100130 A discloses a welding method for ultra-high strength steel plates with a yield strength of 1400MPa, and Chinese patent CN 105598596 A discloses a 1200MPa high strength steel combined welding method without preheating. The above patents mainly use 90KG-grade low-strength welding wire for welding, and the strength of the joints cannot reach the strength of the parent material, which greatly affects the bearing capacity and safety of the high-strength steel welded structure.

[0004] Chinese patent application CN 108637524 A discloses a flux-cored welding wire for 1500MPa ultra-high strength alloy steel welding, and Chinese patent application CN 105234587 A discloses a solid copper-free welding wire for gas shielded welding of 1500MPa ultra-high strength steel. The welding material composition disclosed in the above patents is mainly aimed at the strength index of 1500MPa, without considering the comprehensive performance of 1500MPa ultra-high strength steel under special working conditions in the deep sea. High-strength steel welded structures serve in high-pressure, oxygen-free, low-temperature or locally high-temperature (400°C) environments in the deep sea, which places higher requirements on their strength and low-temperature toughness.

[0005] There are several challenges in welding 1500MPa deep-sea steel: 1) H elements in the marine environment may enter deep-sea steel structures. If the H content in the weld is high, the combined effect of H inside the weld and H in the deep sea will reduce the plasticity of the metal material and cause hydrogen embrittlement. 2) When welding thicker steel plates (≥30mm), it is often necessary to open a larger angle groove and perform multi-layer and multi-pass welding. The welding cycle is long, the interlayer cleaning is difficult, and the labor intensity is high. The fluidity of the deposited metal of high-strength welding materials is poor, which can easily cause poor weld formation and lead to a high rework rate. 3) Ultra-high-strength steel has a high carbon equivalent and high hardenability, and often requires pre- and post-weld heat treatment to reduce welding stress and welding crack tendency, increasing welding costs. Summary of the invention

[0006] According to the technical problems raised above, a 1500MPa deep-sea steel welding material with a thickness greater than 30mm and a welding method thereof are provided. The method is designed to match a 1500MPa deep-sea steel solid welding wire, and adopts a narrow gap hot wire arc welding method and a composite laser remelting process to ensure good weld formation and improve welding efficiency. It can better eliminate moisture adsorbed on the surface of the welding wire, reduce the source of H elements in the weld, reduce the superposition effect of H inside the weld and H in the deep sea, and thus reduce the hydrogen embrittlement sensitivity of the weld. The tensile strength of the deposited metal of the welding wire is greater than 1500MPa, the yield strength is greater than 1380MPa, the elongation is greater than 12%, and the impact energy at -60℃ is greater than 75J, ensuring that the weld has excellent comprehensive performance.

[0007] The technical means adopted by the present invention are as follows:

[0008] A 1500MPa deep-sea steel welding material with a thickness greater than 30mm, the components and mass percentages of which are: 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%, and the rest are Fe and unavoidable impurities.

[0009] Furthermore, as a more preferred scheme, the components and mass percentages are: 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%, and the rest are Fe and unavoidable impurities.

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

[0011] C: The C content ensures that the deposited metal has a high strength. A C content higher than 0.2% will seriously deteriorate the weldability of the deposited metal, and a C content lower than 0.07% will not ensure that the strength of the weld deposited metal is greater than 1000MPa. The weld can ensure a certain C content and a certain Cr and Mo ratio to ensure that the deposited metal precipitates fine M2C carbides during the subsequent heating process, achieving the purpose of secondary strengthening; after comprehensive consideration, the preferred C content of the present invention is 0.08% to 0.13%; Mo: 0.1% to 0.3%, Cr: 0.1% to 0.3%.

[0012] Ni: High Ni content can improve the hardenability of steel, reduce the toughness-brittleness transition temperature and cleavage fracture tendency of the deposited metal, and improve the toughness of the deposited metal; adding Ni can improve the strength of the steel weld without significantly reducing its toughness. A Ni content greater than 3.5% can ensure that the weld metal has good impact toughness at -40°C. After considering other elements, the preferred Ni content of the present invention is 4.5%-8.5%.

[0013] Co: High Co content can delay the recovery of dislocation substructure in martensite, ensuring the formation of fine and dispersed alloy carbides at the dislocation; Co element can increase Ms temperature, and high Co content (greater than 5%) can inhibit the formation of residual austenite, and the weld is easy to form full martensite structure, obtaining ultra-high hardness and good comprehensive mechanical properties. After considering other elements, the preferred Co content of the present invention is 5% to 11%.

[0014] The combined deoxidation of Si and Mn forms MnO·SiO2, which has a low melting point (about 1270°C) and a low density. It can condense into large pieces of slag in the molten pool and float out, achieving a good deoxidation effect. In addition, Mn will react with S to form MnS, which can reduce the tendency of thermal cracks caused by S. In order to ensure the deoxidation effect of the weld, the Si content is not less than 0.3%, but if the Si content is greater than 0.6%, it will cause solid solution hardening of the weld and an increase in the number of secondary phases, causing the weld to become brittle. The preferred Si content of the present invention is 0.3% to 0.6%; the Mn / Si is in the range of 2.3 to 3.8, and the weld can obtain good comprehensive performance.

[0015] Mo: Mo has a great influence on the strength of the weld, but a Mo content greater than 0.5% is detrimental to the elongation and impact performance of the weld. When the Mn content is low, the low content of Mo can balance the strength and toughness of the weld. After comprehensive consideration of other elements, the preferred Mo content of the present invention is 0.1% to 0.3%.

[0016] Ti: A trace amount of Ti is easy to form TiO inclusions during welding, which promotes nucleation in austenite grains and is beneficial to improving the toughness of the deposited metal. When Ti is greater than 0.1%, it will promote the formation of hard phases such as bainite and MA components in the weld structure, which will deteriorate the toughness of the weld. After considering other elements, the preferred Ti content of the present invention is 0.05%-0.08%.

[0017] The present invention also discloses a welding method using the welding material, comprising the following steps:

[0018] Step 1: Design and process the grooves of the steel to be welded, and clean the oil and impurities at the grooves;

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

[0020] Step 3, set welding process parameters, introduce welding shielding gas, adjust the high-pressure gas injection position and flow rate, and perform welding. During the welding process, open the high-pressure gas to spray and cool the weld surface formed by welding; after completing a weld, monitor the weld temperature and start laser remelting after it reaches the preset value;

[0021] Step 4: After the weld is laser remelted, monitor the temperature of the weld until it reaches a preset value before proceeding to the next welding process. After one weld is completed, continue welding according to the above process until the entire welding process is completed.

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

[0023] Furthermore, in step 1, a grinding wheel is used to grind and clean the groove to remove iron oxide and iron filings, and the surface rust and oil stains within 20 to 40 mm on both sides of the groove are cleaned.

[0024] Furthermore, in step 2, the group (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 gun moving speed of 300-500 mm / min.

[0026] Furthermore, in step 3, when welding starts, the adjusting wheel at the rear of the welding gun is adjusted so that high-pressure gas is blown toward the weld surface, the gas flow rate of the high-pressure gas is 100 to 300 L / min, and the pressure of the high-pressure gas is 0.1 to 1 MPa.

[0027] Furthermore, in step 4, when the temperature of the monitored weld reaches 100-160°C, the reciprocating scanning process of laser remelting is started; in step 5, after the weld is laser remelted, when the temperature of the monitored weld is 100-160°C, the next welding work is started.

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

[0029] Further, the components and mass percentages of the 1500MPa deep-sea steel to be welded are: C: 0.1% to 0.5%, Mn: 0.2% to 1.0%, Si: 0.1% to 0.8%, S≤0.002%, P≤0.005%, Ni: 6%-15%, Co: 6% to 15%, Mo: 0.5% to 2.5%, Cr: 1% to 5%, Ti: 0.02% to 0.30%, and the rest are Fe and unavoidable impurities. The rest are Fe and unavoidable impurities.

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

[0031] 1. The present invention is aimed at 1500MPa deep-sea steel. The matching welding wire adopts the design principle of high Co-Ni secondary hardening steel deposited metal, which can control the lower C content to ensure that the weld structure is high-toughness lath martensite. Therefore, no pre-weld heat treatment is required, and the weld still has excellent crack resistance. In addition, through the 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 structure, ensuring that the weld has excellent comprehensive performance.

[0032] 2. The present invention controls the gap D of the weld joint according to the plate thickness T, adopts the hot wire narrow gap welding process, and the welding wire fed into the molten pool carries a low-voltage current, which effectively preheats the welding wire, can better eliminate the moisture adsorbed on the surface of the welding wire, and reduce the source of H elements in the weld. Therefore, in the marine environment (high H environment), the weld with a small amount of H content has a lower sensitivity to hydrogen-induced cracking, eliminating the heat treatment process before welding; in addition, the narrow gap can greatly reduce the filling amount of weld metal and improve welding efficiency.

[0033] 3. During the welding process of the present invention, the high-pressure gas behind the welding gun can quickly increase the cooling speed of the weld, and the baffle will not allow the high-pressure gas to affect the arc burning. The weld is equivalent to undergoing online quenching heat treatment, which improves the strength of the weld. The online heat treatment process formed by spraying high-pressure gas during welding can save a long post-weld heat treatment process and reduce welding costs.

[0034] 4. The surface of the weld of the present invention is subjected to laser remelting treatment to form a remelted layer, and the remelted layer forms a fine grain structure. For multi-layer and multi-pass welding of thick plates, the welding heat flow and heat dissipation direction will cause the coarse dendrite structure in the weld to have obvious orientation characteristics, which can easily cause alloy element segregation and cracking in the weld, and the thermal effect during welding will cause the grain structure of the previous weld to coarsen, resulting in deterioration of the overall performance of the weld. The fine equiaxed grain structure of the remelted layer after the weld surface is laser treated will hinder the growth behavior of coarse dendrites between each pass in the weld, and laser remelting will also perform a short-term tempering treatment on the weld, promoting the precipitation of fine M2C carbides in the remelted layer and improving the strength and toughness of the weld metal. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 paying creative labor.

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

[0037] Figure 2 It is a side schematic diagram of the welding process of the present invention.

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

[0039] Figure 4 It 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 80 mm thick plate joint of the present invention.

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

[0042] In the figure: 1-base material; 2-liner; 31-motor; 32-driving 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 DESCRIPTION

[0043] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0044] 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 only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

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

[0046] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, the numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0047] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

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

[0049] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0050] A 1500MPa deep-sea steel welding material with a thickness greater than 30mm, the components and mass percentages of which are: 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%, and the rest are Fe and unavoidable impurities.

[0051] Further, as a more preferred embodiment, the components and mass percentages of the steel welding material are: 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%, and the rest is Fe and unavoidable impurities.

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

[0053] Step 1, respectively designing grooves for the steel base material 1 to be welded, processing the grooves, and cleaning the oil stains and impurities at the grooves;

[0054] Step 2: confirm the gap between the welded joints based on the thickness of the steel plate; a lining plate 2 with a preset length and thickness is arranged below the two base materials;

[0055] Step 3, set welding process parameters, introduce welding shielding gas, and perform welding; specifically, use 99.99% argon as shielding gas, turn on the motor 31 that controls the swing of the bent tungsten pole 34 of the welding gun, the motor 31 drives the driving gear 32 and the driven gear 33, and then drives the bent tungsten pole 34 at the end of the gun body 35 to swing, so that the heated tungsten pole forms an arc micro-area similar to a fan. Adjust the position of the wire guide tube 5, the dry extension length of the hot wire 6 is 15 to 25 mm, and the wire enters the molten pool 7 formed by the arc after heating, reducing the H content in the weld. At the beginning of welding, adjust the adjustment wheel at the rear of the welding gun so that the high-pressure gas is blown to the weld surface. The online heat treatment process formed by spraying high-pressure gas during welding can save a long post-weld heat treatment process and reduce welding costs.

[0056] Step 4: After completing a weld 4, turn off the high-pressure gas, monitor the temperature of the weld and start laser remelting after it reaches the preset value; the laser remelts the weld surface to form a remelting zone on the weld surface, improves the roughness of the weld surface, removes impurities on the weld surface, makes the weld purer, and eliminates the need for weld cleaning; in addition, the thermal effect of the laser will also perform short-term heat treatment on the micro-area below the weld surface, forming a heat treatment effect similar to tempering, promoting the precipitation of fine precipitates in the weld and improving the comprehensive mechanical properties of the weld.

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

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

[0059] Furthermore, in step 1, a grinding wheel is used to grind and clean the groove to remove iron oxide and iron filings, and the surface rust and oil stains within 25±1 mm on both sides of the groove 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 gun moving speed of 300-500 mm / min.

[0062] Furthermore, in step 3, while welding is started, the adjusting wheel 9 behind the welding gun is adjusted so that the high-pressure gas (compressed air) 11 is blown toward the weld surface 12 through the nozzle 10, and the baffle 8 is adjusted so that the high-pressure gas flow does not affect the arc molten pool, and the gas 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. The deposited metal of the weld is rapidly cooled to achieve a heat treatment effect similar to quenching.

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

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

[0065] Furthermore, the components and mass percentages of the 1500MPa grade deep-sea steel to be welded are: 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%, and the rest are Fe and unavoidable impurities.

[0066] Embodiment 1

[0067] In this embodiment, for welding of 1500MPa deep-sea steel with a plate thickness of 50mm, the alloy composition and mass percentage of the base material are: 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%, and the rest are Fe and unavoidable impurities.

[0068] 1) The composition of the weld metal of the designed welding wire is as follows: 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 rest is Fe and unavoidable impurities.

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

[0070] 3) Set the welding parameters and start welding. Use 99.99% argon as the shielding gas, the gas flow rate is 20L / min, and the hot wire current is 25A. The hot wire current effectively preheats the welding wire, which can better eliminate the moisture adsorbed on the surface of the welding wire and reduce the source of H elements in the weld. In the marine environment (high H environment), welds with a small amount of H content have lower hydrogen-induced cracking sensitivity; the welding current is 270A, the welding voltage is 17V, and the welding gun movement speed is 350mm / min. Turn on the motor that controls the swing of the bent tungsten electrode of the welding gun, so that the heating tungsten electrode forms a fan-like arc micro-area. At the beginning of welding, adjust the adjustment wheel behind the welding gun so that the high-pressure gas blows to the weld surface. The gas flow rate is 150L / min and the gas pressure is 0.6MPa.

[0071] 4) After completing a weld, when the temperature of the weld is monitored to be 110°C, laser remelting treatment 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 sweep of the entire weld surface.

[0072] 5) After the weld is laser remelted, when the temperature of the weld is monitored to be 110°C, the next welding process is started. After one weld is completed, welding is continued according to the above process until the entire welding process is completed. The tensile strength of the weld metal is 1535MPa, the yield strength is 1396MPa, the elongation is 13%, and the impact energy at -60°C is 85J.

[0073] Embodiment 2

[0074] In this embodiment, for welding of 1500MPa deep-sea steel with a plate thickness of 42mm, the alloy composition and mass percentage of the base material are: 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%, and the rest are Fe and unavoidable impurities.

[0075] 1) Design the composition of the weld metal: 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 rest is Fe and inevitable impurities.

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

[0079] 3) Set the welding parameters and start welding. Use 99.99% argon as the shielding gas, the gas flow rate is 20L / min, the hot wire current is 20A, the welding current is 260A, the welding voltage is 16V, and the welding gun moves at a speed of 400mm / min. Turn on the motor that controls the swing of the bent tungsten electrode of the welding gun so that the heated tungsten electrode forms a fan-like arc micro-area. At the beginning of welding, adjust the adjustment wheel at the rear of the welding gun so that the high-pressure gas blows toward the weld surface. The gas flow rate is 200L / min and the gas pressure is 0.4MPa.

[0080] 4) After completing a weld, when the temperature of the weld is monitored to be 110°C, 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 the weld is laser remelted, when the temperature of the weld is monitored to be 110°C, the next welding process is started. After one weld is completed, welding is continued according to the above process until the entire welding process is completed. The tensile strength of the weld metal is 1549MPa, the yield strength is 1410MPa, the elongation is 13.5%, and the impact energy at -60°C is 92J.

[0082] Embodiment 3

[0083] In this embodiment, for welding of 1500MPa deep-sea steel with a plate thickness of 35mm, the alloy composition and mass percentage of the base material are: 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%, and the rest are Fe and unavoidable impurities.

[0084] 1) The composition of the weld metal of the designed welding wire is as follows: 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 rest is Fe and unavoidable impurities.

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

[0086] 3) Set the welding parameters and start welding. Use 99.99% argon as the shielding gas, the gas flow rate is 20L / min, the hot wire current is 22A, the welding current is 265A, the welding voltage is 15V, and the welding gun movement speed is 360mm / min. Turn on the motor that controls the swing of the bent tungsten electrode of the welding gun so that the heating tungsten electrode forms a fan-like arc micro-area. At the beginning of welding, adjust the adjustment wheel at the rear of the welding gun so that the high-pressure gas blows to the weld surface. The gas flow rate is 200L / min and the gas pressure is 0.4MPa.

[0087] 4) After completing a weld, when the temperature of the weld is monitored to be 120°C, 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 the weld is laser-sweep remelted, when the temperature of the weld is monitored to be 120°C, the next welding process is started. After one weld is completed, welding is continued according to the above process until the entire welding process is completed. The tensile strength of the weld metal is 1533MPa, the yield strength is 1405MPa, the elongation is 13.5%, and the impact energy at -60°C is 96J.

[0089] Embodiment 4

[0090] In this embodiment, for welding of 1500MPa deep-sea steel with a plate thickness of 60mm, the alloy composition and mass percentage of the base material are: 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%, and the rest are Fe and unavoidable impurities.

[0091] 1) The composition of the weld metal of the designed welding wire is as follows: 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 rest is Fe and unavoidable impurities.

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

[0093] 3) Set the welding parameters and start welding. Use 99.99% argon as the shielding gas, the gas flow rate is 25L / min, the hot wire current is 30A, the welding current is 290A, the welding voltage is 18V, and the welding gun moves at a speed of 400mm / min. Turn on the motor that controls the swing of the bent tungsten electrode of the welding gun so that the heated tungsten electrode forms a fan-like arc micro-area. At the beginning of welding, adjust the adjustment wheel at the rear of the welding gun so that the high-pressure gas blows toward the weld surface. The gas flow rate is 200L / min and the pressure of the high-pressure gas is 1MPa.

[0094] 4) After completing a weld, when the temperature of the weld is monitored to be 130°C, 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 the weld is laser remelted, when the temperature of the weld is monitored to be 130°C, the next welding process is started. After one weld is completed, welding is continued according to the above process until the entire welding process is completed. The tensile strength of the weld metal is 1547MPa, the yield strength is 1403MPa, the elongation is 12.5%, and the impact energy at -60°C is 88J.

[0096] Embodiment 5

[0097] In this embodiment, for welding of 1500MPa deep-sea steel with a plate thickness of 65mm, the alloy composition and mass percentage of the base material are: 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%, and the rest are Fe and unavoidable impurities.

[0098] 1) The composition of the weld metal of the designed welding wire is as follows: 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 rest is Fe and unavoidable impurities.

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

[0100] 3) Set the welding parameters and start welding. Use 99.99% argon as the shielding gas, the gas flow rate is 22L / min, the hot wire current is 30A, the welding current is 290A, the welding voltage is 18V, and the welding gun moves at a speed of 300mm / min. Turn on the motor that controls the swing of the bent tungsten electrode of the welding gun, so that the heating tungsten electrode forms a fan-like arc micro-area. At the beginning of welding, adjust the adjustment wheel at the rear of the welding gun so that the high-pressure gas blows toward the weld surface. The gas flow rate is 250L / min and the gas pressure is 0.5MPa.

[0101] 4) After completing a weld, when the temperature of the weld is monitored to be 110°C, 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 the weld is laser remelted, when the temperature of the weld is monitored to be 110°C, the next welding process is started. After one weld is completed, welding is continued according to the above process until the entire welding process is completed. The tensile strength of the weld metal is 1526MPa, the yield strength is 1378MPa, the elongation is 13%, and the impact energy at -60°C is 85J.

[0103] Embodiment 6

[0104] In this embodiment, the 1500MPa deep-sea steel with a plate thickness of 80mm is welded, and the alloy composition and mass percentage of the parent material are: 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%, and the rest are Fe and unavoidable impurities. The macroscopic photos and micro-area scanning photos of the weld of this embodiment are shown in Figures 1 and 2. Figure 5 , Figure 6 shown.

[0105] 1) The composition of the weld metal of the designed welding wire is as follows: 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 rest is Fe and unavoidable impurities.

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

[0107] 3) Set the welding parameters and start welding. Use 99.99% argon as the shielding gas, the gas flow rate is 25L / min, the hot wire current is 32A, the welding current is 300A, the welding voltage is 19V, and the welding gun movement speed is 350mm / min. Turn on the motor that controls the swing of the bent tungsten electrode of the welding gun so that the heating tungsten electrode forms a fan-like arc micro-area. At the beginning of welding, adjust the adjustment wheel at the rear of the welding gun so that the high-pressure gas blows to the weld surface. The gas flow rate is 250L / min and the gas pressure is 0.5MPa.

[0108] 4) After completing a weld, when the temperature of the weld is monitored to be 130°C, 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 the weld is laser remelted, when the temperature of the weld is monitored to be 130°C, the next welding process is started. After one weld is completed, welding is continued according to the above process until the entire welding process is completed. The tensile strength of the weld metal is 1516MPa, the yield strength is 1398MPa, the elongation is 12.8%, and the impact energy at -60°C 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned 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 components and mass percentages are: 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%, and the rest are 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 components and mass percentages are: 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%, the rest are Fe and unavoidable impurities, 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: The following steps are involved: Step 1: Design and process the grooves of the steel to be welded, and clean the oil and impurities at the grooves; Step 2: Determine the gap between the welded joints based on the thickness of the steel plate; Step 3, setting welding process parameters, introducing welding shielding gas, and adjusting the high-pressure gas injection position and flow rate, and welding. During the welding process, high-pressure gas is turned on to spray and cool the weld surface formed by welding; After completing a weld, the temperature of the weld is monitored and reaches the preset value, and then the laser remelting process begins; Step 4: After the weld is laser remelted, monitor the temperature of the weld until it reaches a preset value before proceeding to the next welding process. After one weld is completed, continue welding according to the above process until the entire welding process is completed.

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

5. The method according to claim 3, characterized in that: In step 2, the gap D of the welded joints 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 is 20-25 L / min, hot wire current is 20-50 A, welding current is 250-350 A, welding voltage is 15-20 V, and welding gun moving speed is 300-500 mm / min.

7. The method according to claim 3, characterized in that In step 3, when welding starts, adjust the adjustment wheel at the rear of the welding gun so that high-pressure gas is blown toward the weld surface. The gas flow rate of the high-pressure gas is 100 to 300 L / min, and the pressure of the high-pressure gas is 0.1 to 1 MPa.

8. The method according to claim 3, characterized in that In step 4, when the temperature of the monitored weld reaches 100-160°C, the reciprocating scanning process of laser remelting is started; in step 5, after the weld is laser remelted, when the temperature of the monitored weld is 100-160°C, the next welding work is started.

9. The method according to claim 3, characterized in that: The laser remelting process parameters The invention comprises: the focusing mode of the laser is defocusing, 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 components and mass percentages of the 1500MPa grade deep-sea steel to be welded are: 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%, and the rest are Fe and unavoidable impurities.

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