A narrow gap hot wire TIG- electrode combined welding method of high-strength wear-resistant steel

Abstract

The present application relates to a kind of high-strength wear-resistant steel narrow gap hot wire TIG electrode composite welding method, design U-shaped groove, bottom is left 2~3mm blunt edge, by the advanced welding method and welding process of the combination of narrow gap hot wire TIG welding and traditional manual electrode arc welding, weld backing welding and filling welding adopt narrow gap hot wire TIG welding, cap welding adopts manual electrode arc welding, the beneficial effects of the present application: ensure the efficient welding of thick gauge wear-resistant steel and the quality and performance of welded joint, while having the toughness of weld, corrosion resistance, abrasion resistance and other excellent performance of wear-resistant steel weld, less welding workload, weld effect is good, provide welding technical support for the popularization and application of high-strength wear-resistant steel.

Description

Technical Field

[0001] This invention relates to the field of welding technology for thick-gauge high-strength wear-resistant steel, and particularly to a composite welding method for high-strength wear-resistant steel with narrow gap hot wire TIG-electrode. Background Technology

[0002] With the development of my country's national economy and society, the use of construction machinery and equipment is extremely frequent during the construction of large-scale real estate, bridges, tunnels, roads, and other infrastructure projects. Therefore, the use of wear-resistant steel in construction machinery is gradually increasing.

[0003] However, there are also some problems in the manufacturing of engineering machinery equipment with high-strength wear-resistant steel: (1) The carbon equivalent of high-strength wear-resistant steel is generally higher than that of ordinary low-alloy high-strength steel, and the weldability is poor. Delayed cracks are easy to occur after welding, which affects the usability of high-strength wear-resistant steel equipment; (2) Since high-strength wear-resistant steel generally uses low-strength matching welding materials, the wear resistance of the weld is lower than that of the base material. During use, the wear of the weld is relatively large, and the weld is easily worn and damaged, which affects the service life of high-strength wear-resistant steel equipment; (3) The thickness of thick wear-resistant steel plates is large, which leads to a large amount of welding work, poor weld quality, and poor weld welding effect, which affects the use of high-strength wear-resistant steel equipment. At this time, the appropriate welding process plays a crucial role in the quality and performance of the welded joint. Single welding methods, such as shielded metal arc welding, gas shielded welding, and submerged arc welding, each have their own advantages and obvious disadvantages. After adopting a new composite welding method, the corresponding welding process and parameters need to be changed accordingly to ensure the mechanical properties of the welded joint.

[0004] Patent CN114309899B, "A Welding Method for Low-Alloy Wear-Resistant Steel and its Welded Joint," discloses a welding method for low-alloy wear-resistant steel, comprising the following steps: first, processing a welding bevel on the wear-resistant steel to be welded; preheating the welding bevel and the wear-resistant steel on both sides of the welding bevel; then, performing the root pass and fill pass welding using a double-fine-wire submerged arc welding method; finally, performing the cover pass welding using a cold-wire-filled double-fine-wire submerged arc welding method. The patent also discloses the welded joint obtained by the above welding method. In this patent's welding method, the root pass and fill pass welding use double-fine-wire submerged arc welding, and the cover pass welding uses cold-wire-filled double-fine-wire submerged arc welding. While ensuring the comprehensive mechanical properties of the weld, it improves wear resistance, and the welding efficiency is 2-3 times higher than existing mature welding technologies. Furthermore, it achieves essentially the same wear amount between the weld and the base material under the same working conditions, extending service life. However, the X-shaped or V-shaped bevel used in this method is not suitable for welding thick steel plates, and is prone to defects such as porosity, incomplete penetration, incomplete fusion, or pits. In addition, the welding operation of this patent is huge, the amount of manual labor is huge, the welding quality cannot be guaranteed, the weld effect is poor, which affects the usability of high-strength wear-resistant steel and the scope of application of high-strength wear-resistant steel.

[0005] Patent CN110238528B, "A Laser-Hot Wire TIG Composite Welding Method with Normal Wire Feeding," relates to a laser-hot wire TIG composite welding method with normal wire feeding. The method includes: designing a welding bevel at the welding location on the thick plate to be welded; using a high-power laser for deep penetration welding to achieve the root pass of the bevel's blunt edge; employing a combination of laser beam, non-consumable electrode, and continuously heated welding wire to perform layer-by-layer filling welding on the bevel of the thick plate to be welded. During the welding process, the height of the composite welding torch above the molten pool should be adjusted according to the thickness of each layer. The welding wire is induction heated by a hot wire heating device. In the welding feed direction, the laser beam is positioned in front of the welding wire, and the non-consumable electrode is positioned behind the welding wire and placed in an inert gas protective hood. The above composite welding method is used to perform a cover pass welding on the bevel weld of the thick plate to complete the composite welding. However, laser-composite-hot-wire TIG composite welding cannot guarantee the wear resistance of the weld, easily causing severe wear and damage to the weld, affecting the equipment's functionality, reducing its effectiveness, and shortening its service life.

[0006] Patent CN115635253A, "A Welded-Clad Composite Weld of Wear-Resistant Steel and Its Welding Method," discloses a welded-cladding composite weld of wear-resistant steel and its welding method. The welded composite weld includes an inner low-alloy steel filler layer and an outer WC particle-reinforced nickel-based alloy capping layer and / or sealing layer. The filler layer is obtained by gas shielded welding with low-alloy steel welding wire. The capping layer is obtained by laser cladding technology using residual heat from fusion welding. The sealing layer is obtained by melting using residual heat from fusion welding. The weld provided by this patent uses a composite weld of low-alloy steel and WC particle-reinforced nickel-based alloy. The internal low-alloy steel filler layer has excellent mechanical properties, and the external WC particle-reinforced nickel-based alloy capping / sealing layer has good wear resistance. This allows the welded joint to have both good mechanical properties and wear resistance. However, this method has poor welding effect and poor welding quality for thick-gauge high-strength wear-resistant steel. It is prone to obvious defects such as welding pits. The weld strength is lower than that of the high-strength wear-resistant steel itself, which affects its use. Furthermore, the corrosion resistance and wear resistance are poor, which limits the application range of high-strength wear-resistant steel. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, this invention provides a narrow-gap hot-wire TIG-electrode composite welding method for high-strength wear-resistant steel. The method involves designing a U-shaped bevel with a 2-3mm blunt edge at the bottom. It combines the advanced narrow-gap hot-wire TIG welding method with traditional manual shielded metal arc welding. The root pass and fill pass are performed using narrow-gap hot-wire TIG welding, while the cover pass is performed using manual shielded metal arc welding. This method ensures efficient welding of thick-gauge wear-resistant steel and the quality and performance of the weld joint. Simultaneously, it produces a wear-resistant steel weld with excellent properties such as toughness, corrosion resistance, and wear resistance. The method requires less welding work and produces good weld results, providing welding technology support for the widespread application of high-strength wear-resistant steel.

[0008] To achieve the above objectives, the present invention employs the following technical solution:

[0009] A composite welding method for high-strength wear-resistant steel using narrow-gap hot-wire TIG welding and manual electrode welding is disclosed. This method combines narrow-gap hot-wire TIG welding with manual electrode arc welding. The composite welding method for high-strength wear-resistant steel using narrow-gap hot-wire TIG welding includes the following:

[0010] S1. Welding bevel processing: Based on the welding characteristics of narrow gap hot wire TIG welding and the shape of the welding torch, a U-shaped bevel is designed with a blunt edge of 2-3mm at the bottom.

[0011] S2. The bevel is removed by mechanical processing. Before welding, the oxides and impurities in the weldable area of ​​the base steel plate are removed by angle grinding, and the interface is wiped with industrial alcohol until the metal luster is exposed.

[0012] S3. After the high-strength wear-resistant steel plates to be welded have been beveled, they are assembled and placed with a relative gap of 2-3mm between the bottom blunt edges.

[0013] S4. Preheat the area to be welded to 100-120℃.

[0014] S5. Use narrow-gap hot-wire TIG welding for root pass and fill pass welding, and use inert gas flow protection during the welding process;

[0015] S6. When using narrow-gap hot wire TIG welding for filler welding, increase the welding current by 20-60A and stop the filler welding when it is 7-8mm away from the top of the groove.

[0016] S7. Using manual shielded metal arc welding, weld the TIG filler weld bead up to the top of the groove for the capping weld.

[0017] After completing the S8, narrow-gap hot wire TIG welding and manual shielded metal arc welding composite welding, cover the weld joint with insulation cotton to reduce the cooling rate of the weld joint.

[0018] Furthermore, in step S5, the narrow gap hot wire TIG welding uses JQ.TG50 carbon steel argon arc welding wire with a tensile strength Rm>490MPa and an impact energy Kv2>27J at -30℃.

[0019] Furthermore, in step S5, the welding current for narrow-gap hot-wire TIG welding is 110–180A, the welding voltage is 12–16V, the welding speed is 100–150mm / min, and the oscillation width is 2mm.

[0020] Furthermore, in step S5, high-purity argon is used as the protective gas. Before welding, argon is blown into the weld seam for 3 seconds to fill the bottom of the weld seam with argon, and then a narrow-gap hot wire TIG root pass welding operation is performed.

[0021] Furthermore, in step S7, the cover welding includes cover corrosion-resistant layer welding and cover wear-resistant layer welding. The cover corrosion-resistant layer is welded on top of the TIG filler weld bead, and the cover wear-resistant layer is welded on top of the cover corrosion-resistant layer to the top surface of the bevel.

[0022] Furthermore, the welding of the corrosion-resistant cover layer is carried out by manual shielded metal arc welding, using A132 stainless steel welding rods with a diameter of 3.2mm, welding current of 70-90A, welding voltage of 14-16V, and welding speed of 100-120mm / min.

[0023] Furthermore, the wear-resistant layer of the cover is welded using manual shielded metal arc welding, with D167 low-hydrogen sodium coated manganese silicon type welding rods, which are small-sized welding rods with a diameter of 3.2mm. The welding current is 85-100A, the welding voltage is 16-20V, and the welding speed is 100-120mm / min.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1) The use of narrow-gap hot wire TIG welding for the root and filler welds results in low heat input, fewer welding passes, and less welding workload. This greatly reduces the probability of welding cracks in the welded joints of thick wear-resistant steel, ensuring efficient welding of thick wear-resistant steel and the quality and performance of the welded joints.

[0026] 2) Narrow-gap hot wire TIG welding reduces the heat input of the welding process and can also reduce the area of ​​the heat-affected zone, thereby reducing the area of ​​decreased hardness and wear resistance. This can, to a certain extent, prevent the hardness of the welded joint from decreasing and obtain high-strength wear-resistant steel welds with excellent properties such as toughness, corrosion resistance, and friction and wear resistance.

[0027] 3) Using narrow-gap hot wire TIG welding can reduce the bevel area, reduce the amount of welding work, and reduce the time required for welding processes. Compared with existing technologies, it can reduce welding operation time by 30%-50%, reduce welding costs, and bring economic benefits to production units.

[0028] 4) Using shielded metal arc welding (SMAW) with stainless steel electrodes and wear-resistant surfacing electrodes for weld cover welding can form a wear-resistant and corrosion-resistant layer with excellent hardness, wear resistance, and corrosion resistance on the weld surface. This reduces the difference in wear resistance between the weld and the base material, improves the corrosion resistance of the weld, and increases corrosion resistance by 50% compared with existing technologies. It also prevents the formation of "pits" in the weld of high-strength wear-resistant steel under heavy wear and corrosion during use, improves the performance of high-strength wear-resistant steel equipment, extends its service life, and provides welding technology support for the promotion and application of high-strength wear-resistant steel.

[0029] 5) Using shielded metal arc welding for cover welding is simple, easy to operate and carry, and allows for quick repair of damaged weld surfaces, reducing the impact on on-site production and lowering enterprise costs.

[0030] 6) The mechanical properties of the composite weld were tested through tensile and impact tests. The tensile strength Rm of the weld was greater than 490 MPa, and the impact energy Kv2 at -30℃ was greater than 27 J. Compared with the existing technology, the corrosion resistance was improved by 50%, and the friction and wear resistance was improved by 100%. Its friction and wear resistance was higher than that of ordinary welding materials, and the hardness was greater than 700 HV. This comprehensively improved the welding performance of high-strength wear-resistant steel, improved the welding quality, increased the use value of high-strength wear-resistant steel, expanded the application range, and increased the economic value. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the welding process described in this invention.

[0032] Figure 2 This is a schematic diagram of the bevel form described in this invention.

[0033] In the diagram: 1. Steel plate to be welded; 2. Bevel; 3. Weld; 4. Root pass welding; 5. Filler pass welding; 6. Cover pass welding; 7. Cover pass corrosion-resistant layer welding; 8. Cover pass wear-resistant layer welding. Detailed Implementation

[0034] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0035] Example 1:

[0036] This embodiment is applied to the welding of 45mm thick NM500 high-strength wear-resistant steel plates. The specific implementation process is as follows:

[0037] like Figures 1-2As shown, a narrow-gap U-shaped bevel 2 is machined on the steel plate 1 to be welded using a machining method. Two steel plates 1 to be welded are processed together. A single-sided half-U-shaped bevel 2 is machined on the side of the welded side of each steel plate 1, with a 2mm blunt edge at the bottom. The two sides of the welded side of the two steel plates to be welded together form a U-shaped bevel 2. Before welding, a grinding wheel is used to clean and grind the bevel 2 and the 20mm area on both sides of the weld 3 until it is bright and free of obvious oil stains, rust and other impurities.

[0038] Fix the steel plate 1 with the bevel 2 cut on the workbench for welding. Insert the welding torch into the bottom of the weld 3, and after spraying high-purity argon shielding gas for 3 seconds, perform the root pass welding 4 using a welding current of 110A. Perform two layers of root pass welding 4, each layer consisting of two passes. After root pass welding 4, perform narrow-gap hot-wire TIG welding 5, with a welding current of 170A, 120mm / min, and an oscillation width of 2mm. Perform 14 layers of filler welding, each layer consisting of two passes. Filler welding 5 ends 8mm from the top surface of the bevel 2. The shielding gas flow rate during root pass welding 4 and filler welding 5 is 15L / min.

[0039] The cover welding 6 was performed using A132 manual electrode arc welding to prepare the cover corrosion-resistant layer 7. The welding current was 90A, the welding speed was 100mm / min, the electrode diameter was 3.2mm, and the cover corrosion-resistant layer 7 consisted of 1 weld layer with 2 welding passes.

[0040] The cover weld 6 was prepared using D167 manual electrode arc welding to prepare the wear-resistant layer 8. The welding current was 100A, the welding speed was 100mm / min, and the electrode diameter was 3.2mm. The wear-resistant layer 8 consisted of 2 weld layers and 2 passes.

[0041] After the cover weld 6 was completed, the surface of weld 3 was covered with insulating cotton until it slowly cooled to room temperature to reduce the cooling rate of the weld joint and avoid delayed cracking. After 72 hours, weld 3 was inspected for defects such as cracks and porosity. The results showed that the surface weld had no defects such as cracks and porosity, and the welding quality was good.

[0042] The mechanical properties of the weld were tested by tensile and impact tests. The tensile strength Rm was 553 MPa, and the impact energy Kv2 at -30℃ was 94 J. Compared with the existing technology, the corrosion resistance was improved by 50%, and the friction and wear resistance was improved by 100%. Its friction and wear resistance was higher than that of ordinary welding materials, and the hardness reached 834 HV.

[0043] Example 2:

[0044] This embodiment is applied to the welding of 55mm thick NM500 high-strength wear-resistant steel plates. The specific implementation process is as follows:

[0045] like Figures 1-2As shown, a narrow-gap U-shaped bevel 2 is machined on the steel plate 1 to be welded using a machining method. Two steel plates 1 to be welded are processed together. A single-sided half-U-shaped bevel 2 is machined on the side of the welded side of each steel plate 1, with a 2mm blunt edge at the bottom. The two sides of the welded side of the two steel plates to be welded together form a U-shaped bevel 2. Before welding, a grinding wheel is used to clean and grind the bevel 2 and the 20mm area on both sides of the weld 3 until it is bright and free of obvious oil stains, rust and other impurities.

[0046] The steel plate 1, with its bevel 2 already prepared, is fixed on the worktable in preparation for welding. The welding torch is pre-inserted into the bottom of the weld seam 3, and after spraying high-purity argon shielding gas for 3 seconds, a 110A welding current is used for the root pass 4. Two layers of root pass 4 are performed, each with 3 passes. Following root pass 4, narrow-gap hot-wire TIG welding is performed for filler welding 5, with a welding current of 160A, 120mm / min, and an oscillation width of 2mm. Sixteen layers of filler welding are performed, each with 2 passes, ending 8mm from the top surface of the bevel 2. The shielding gas flow rate is 15L / min during both root pass 4 and filler welding 5.

[0047] The cover welding 6 was performed using A132 manual electrode arc welding to prepare the cover corrosion-resistant layer 7. The welding current was 80A, the welding speed was 100mm / min, the electrode diameter was 3.2mm, and the cover corrosion-resistant layer 7 consisted of 1 weld layer with 2 welding passes.

[0048] The wear-resistant layer of the capping weld 6 was prepared using D167 manual electrode arc welding. The welding current was 95A, the welding speed was 100mm / min, and the electrode diameter was 3.2mm. The wear-resistant layer 8 consisted of two weld layers, with two welding passes.

[0049] After the cover weld 6 was completed, the surface of weld 3 was covered with insulating cotton until it slowly cooled to room temperature to reduce the cooling rate of the weld joint and avoid delayed cracking. After 72 hours, weld 3 was inspected for defects such as cracks and porosity. The results showed that the surface weld had no defects such as cracks and porosity, and the welding quality was good.

[0050] The mechanical properties of the weld were tested by tensile and impact tests. The tensile strength Rm was 572 MPa, and the impact energy Kv2 at -30℃ was 103 J. Compared with the existing technology, the corrosion resistance was improved by 50%, and the friction and wear resistance was improved by 100%. Its friction and wear resistance was higher than that of ordinary welding materials, and the hardness reached 789 HV.

[0051] Example 3:

[0052] This embodiment is applied to the welding of 65mm thick NM500 high-strength wear-resistant steel plates. The specific implementation process is as follows:

[0053] like Figures 1-2As shown, a narrow-gap U-shaped bevel 2 is machined on the steel plate 1 to be welded using a machining method. Two steel plates 1 to be welded are processed together. A single-sided half-U-shaped bevel 2 is machined on the side of the welded side of each steel plate 1, with a 2mm blunt edge at the bottom. The two sides of the welded side of the two steel plates to be welded together form a U-shaped bevel 2. Before welding, a grinding wheel is used to clean and grind the bevel 2 and the 20mm area on both sides of the weld 3 until it is bright and free of obvious oil stains, rust and other impurities.

[0054] Fix the steel plate 1 with the bevel 2 cut on the workbench for welding. Insert the welding torch into the bottom of the weld 3, spray high-purity argon shielding gas for 3 seconds, and then perform the root pass welding 4 using a welding current of 110A. Perform two layers of root pass welding 4, each layer consisting of two passes. After root pass welding 4, perform narrow-gap hot-wire TIG welding 5, with a welding current of 150A, 120mm / min, and an oscillation width of 2mm. Perform 18 layers of filler welding, each layer consisting of two passes. Filler welding 5 ends 8mm from the top surface of the bevel 2. The shielding gas flow rate during root pass welding 4 and filler welding 5 is 15L / min.

[0055] The cover welding 6 was performed using A132 manual electrode arc welding to prepare the cover corrosion-resistant layer 7. The welding current was 70A, the welding speed was 100mm / min, the electrode diameter was 3.2mm, and the cover corrosion-resistant layer 7 consisted of 1 weld layer with 2 welding passes.

[0056] The cover weld 6 was prepared using D167 manual electrode arc welding to prepare the wear-resistant layer 8. The welding current was 85A, the welding speed was 100mm / min, and the electrode diameter was 3.2mm. The wear-resistant layer 8 consisted of 2 weld layers and 2 passes.

[0057] After the cover weld 6 was completed, the surface of weld 3 was covered with insulating cotton until it slowly cooled to room temperature to reduce the cooling rate of the weld joint and avoid delayed cracking. After 72 hours, weld 3 was inspected for defects such as cracks and porosity. The results showed that the surface weld had no defects such as cracks and porosity, and the welding quality was good.

[0058] The mechanical properties of the weld were tested by tensile and impact tests. The tensile strength Rm was 546MPa and the impact energy Kv2 at -30℃ was 86J. Compared with the existing technology, the corrosion resistance was improved by 50% and the friction and wear resistance was improved by 100%. Its friction and wear resistance was higher than that of ordinary welding materials, and the hardness reached 792HV.

[0059] Process parameter table:

[0060]

[0061] Different welding currents are used for different steel plate thicknesses. The thicker the steel plate, the greater the welding stress during welding. Using a smaller welding current reduces heat input and avoids welding cracks.

[0062] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A composite welding method for high-strength wear-resistant steel using narrow-gap hot-wire TIG welding and manual electrode welding, characterized in that: The aforementioned high-strength wear-resistant steel narrow-gap hot-wire TIG-electrode composite welding method includes the following: S1. Welding bevel processing: Based on the welding characteristics of narrow gap hot wire TIG welding and the shape of the welding torch, a U-shaped bevel is designed with a blunt edge of 2-3mm at the bottom. S2. The bevel is removed by mechanical processing. Before welding, the oxides and impurities in the weldable area of ​​the base steel plate are removed by angle grinding, and the interface is wiped with industrial alcohol until the metal luster is exposed. S3. After the high-strength wear-resistant steel plates to be welded have been beveled, they are assembled and placed with a relative gap of 2-3mm between the bottom blunt edges. S4. Preheat the area to be welded to 100-120℃. S5. Use narrow-gap hot-wire TIG welding for root pass and fill pass welding, and use inert gas flow protection during the welding process; S6. When using narrow-gap hot wire TIG welding for filler welding, increase the welding current by 20-60A and stop the filler welding when it is 7-8mm away from the top surface of the groove. S7. Using manual shielded metal arc welding, weld the cover weld from the TIG filler weld to the top surface of the groove. The cover weld includes the cover corrosion-resistant layer weld and the cover wear-resistant layer weld. The cover corrosion-resistant layer weld is above the TIG filler weld, and the cover wear-resistant layer weld is above the cover corrosion-resistant layer to the top surface of the groove. After completing the S8, narrow-gap hot wire TIG arc welding and manual electrode arc welding composite welding, cover the weld joint with insulation cotton to reduce the cooling rate of the weld joint.

2. The method for composite welding of high-strength wear-resistant steel with narrow gap hot wire TIG-electrode according to claim 1, characterized in that, In step S5, the narrow gap hot wire TIG welding uses JQ.TG50 carbon steel argon arc welding wire with a tensile strength Rm>490MPa and an impact energy Kv2>27J at -30℃.

3. The method for composite welding of high-strength wear-resistant steel with narrow gap hot wire TIG-electrode according to claim 1, characterized in that, In step S5, the welding current for narrow-gap hot wire TIG welding is 110-180A, the welding voltage is 12-16V, the welding speed is 100-150mm / min, and the oscillation width is 2mm.

4. The method for composite welding of high-strength wear-resistant steel with narrow gap hot wire TIG-electrode according to claim 1, characterized in that, In step S5, high-purity argon is used as the protective gas. Before welding, argon is blown into the weld seam for 3 seconds to fill the bottom of the weld seam with argon. Then, a narrow-gap hot wire TIG root pass welding operation is performed.

5. The method for composite welding of high-strength wear-resistant steel with narrow gap hot wire TIG-electrode according to claim 1, characterized in that, The corrosion-resistant cover layer is welded using manual shielded metal arc welding (SMAW). The welding material is A132 stainless steel welding rod with a diameter of 3.2 mm. The welding current is 70-90A, the welding voltage is 14-16V, and the welding speed is 100-120 mm / min.

6. The method for composite welding of high-strength wear-resistant steel with narrow gap hot wire TIG-electrode according to claim 1, characterized in that, The wear-resistant cover layer is welded using manual shielded metal arc welding (SMAW). The welding material used is D167 low-hydrogen sodium coated manganese silicon type welding electrode with a diameter of 3.2 mm. The welding current is 85-100A, the welding voltage is 16-20V, and the welding speed is 100-120mm / min.

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