Argon arc welding method for high-strength steel made of BS700MCK2

Abstract

The invention relates to an argon arc welding method for high-strength steel made of BS700MCK2, and relates to the technical field of argon arc welding. Comprising the steps that a welding part with a V-shaped groove, a high-strength steel welding wire corresponding to the welding part and a welding tool are obtained through preparation before welding. Wherein the welding piece is made of high-strength steel made of a BS700MCK2 material, and the welding wire is made of a GHQ80 material; the welding piece is installed in a tool, and argon tungsten-arc welding tack welding is conducted; argon tungsten-arc welding is carried out for root welding; consumable electrode argon arc welding filling welding is carried out; and trimming the appearance of the welding seam and checking a welding bead. According to the method, argon arc welding of the high-strength steel made of BS700MCK2 is achieved in the modes of heat affected zone cleaning, groove numerical control machining, fixable and preheated welding piece tools, argon tungsten-arc welding point fixing, root welding, consumable electrode argon-arc welding filling and the like, cracks are avoided, and meanwhile the quality of welding seams is good and the welding seams are attractive.

Description

Technical Field

[0001] The invention relates to the technical field of argon arc welding, in particular to a high-strength steel argon arc welding method using BS700MCK2 as the material. Background Art

[0002] BS700MCK2 material high-strength steel is one of Baosteel's BS series high-strength steels, and is a low-alloy high-strength structural steel. It not only has high yield strength and tensile strength, but also maintains good plasticity and toughness, and is widely used in manufacturing industries such as mechanical equipment, vehicle structures, and pressure vessels.

[0003] The high-strength properties of BS700MCK2 high-strength steel structures make them highly sensitive to welding cracks. If improper process measures are taken during the welding process, the tensile strength of the weld will decrease, and defects such as cracks and lack of fusion will also easily occur, leaving great quality risks for product applications.

[0004] Therefore need a kind of material is BS700MCK2 high strength steel argon arc welding method to solve the above-mentioned problem. Summary of the invention

[0005] In order to solve the problems of the prior art, the present invention provides a high-strength steel argon arc welding method using BS700MCK2 as the material.

[0006] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0007] A high-strength steel argon arc welding method using BS700MCK2 as the material comprises the following steps:

[0008] Step 1: Pre-welding preparation, including cleaning the heat-affected zone of the weldment, CNC machining the weldment with a V-shaped groove, and making a set of welding tools that can fix and preheat the weldment;

[0009] Step 2: Install the welded parts in the tooling and fix them with tungsten inert gas arc welding;

[0010] Step 3: Root welding with argon tungsten arc welding;

[0011] Step 4: Apply consumable argon arc welding to fill the welding;

[0012] Step 5: Repair the weld appearance and inspect the weld.

[0013] In some specific embodiments, the pre-welding preparation further includes:

[0014] Use a wire brush to polish the heat-affected zone of the welded parts within 40 mm to remove corrosion pits and rust spots on the surface until the metallic luster is revealed;

[0015] A single-sided V-shaped groove is CNC machined on the long side of the weldment, with a groove angle of 30 degrees, a blunt edge between 0.5mm and 1mm, and a groove surface roughness Ra value of no more than 3.2um;

[0016] Make a set of welding tooling. A platform for fixing the welded parts is set on the upper side of the tooling. The height of the pressure plates at both ends can be adjusted by rotating bolts. A gap of not less than 80mm is left at the bottom of the tooling. If necessary, use the flame spray gun at the bottom of the tooling for flame preheating.

[0017] In some specific embodiments, installing the welded part in the tooling and performing tungsten inert gas arc welding on the welded part further comprises:

[0018] Two welded parts with the size of 6mm×100mm×200mm are butt-jointed and assembled together, and placed on the fixed platform of the tooling. The pressure plates at both ends are fastened with bolts to press the welded parts into the tooling, and the butt gap of the welded parts is adjusted to the range of 0 to 0.5mm;

[0019] Tungsten inert gas welding is applied with a weld every 100mm or so, the weld penetrates the blunt edge, the weld length is 2-4mm, the weld angle height is 1-2mm, the welding wire specification is φ2mm, the welding current is 240-280A, the welding voltage is 27V, the shielding gas is 80% Ar and 20% CO2, and the shielding gas flow rate is 20-24L / min.

[0020] In some specific embodiments, applying argon tungsten arc welding to the root further comprises:

[0021] Tungsten inert gas welding was used with manual filler wire moving slowly from one side to the other, with 4 passes applied and 3 layers welded;

[0022] The first layer of welding is done with low current and slow speed to ensure that the blunt edge is fully melted;

[0023] The second layer of welding uses high current, high voltage and fast welding, and the interlayer temperature must not be lower than 150℃;

[0024] The current, voltage and speed of the third layer welding are the same as those of the second layer, and the interlayer temperature must not be lower than 150℃;

[0025] The thickness of the three-layer weld after welding is 2 to 3 mm.

[0026] In some specific embodiments, specific parameters of tungsten inert gas arc welding include:

[0027] During the first layer welding, the welding wire specification is φ2mm, the welding current is 120-160A, the welding voltage is 24V, the welding speed is 100-140mm / min, the shielding gas is a mixture of 80% Ar and 20% CO2, and the shielding gas flow rate is 10-16L / min;

[0028] During the welding process of the second and third layers, the current was adjusted to 180-220A, the welding voltage was adjusted to 27V, the welding speed was adjusted to 180-240mm / min, and the other welding parameters were the same as those of the first layer.

[0029] In some specific embodiments, applying TIG welding to fill the weld further comprises:

[0030] When the temperature cannot reach the welding condition, start the flame spray gun at the bottom of the tooling to preheat the local flame. The preheating range is within 40mm around the weld width.

[0031] Use multi-layer and multi-pass welding to ensure that the interlayer temperature of each layer is not less than 150℃;

[0032] When welding the last layer, the excess height is controlled between 0.5 and 1.5 mm, the weld and the base material have a smooth transition, and the weld filling thickness is 2 to 3 mm.

[0033] In some specific embodiments, the specific parameters of multi-layer and multi-pass welding of metal-arc argon arc welding include:

[0034] The welding wire specification is φ1.2mm, the welding current is 200~240A, the welding voltage is 27V, the welding speed is 220~260mm / min, the shielding gas is 80% Ar and 20% CO2, and the shielding gas flow rate is 16~20L / min.

[0035] In some specific embodiments, repairing the weld appearance and inspecting the weld bead further comprises:

[0036] Use a wire brush or hand grinding wheel to grind the weld, remove the welding slag at the edge of the weld, and trim the uneven texture of the weld.

[0037] In some specific embodiments, the inspection of the weld may be performed by experimental verification to illustrate its structural characteristics, which may specifically include X-ray testing and mechanical testing.

[0038] Specifically, in X-ray testing, the weld after arc welding is mainly tested for defects such as cracks, weld bumps, pores, slag inclusions, etc., which meets the requirements of QJ176A Class I quality standard. In mechanical testing, test pieces are cut from welded parts after arc welding and placed on a tensile testing machine for mechanical property testing. The tensile strength of the test piece reaches more than 90% of the lower limit of the tensile strength of the parent material.

[0039] In some specific implementations, the above-mentioned spot welding, root welding, and filling welding all have temperature requirements during the welding process, and the ambient temperature must be >10°C and the humidity must be ≤75%.

[0040] The beneficial effects of the present invention are:

[0041] 1. The present invention cleans the heat-affected zone through pre-welding preparation to ensure the purity of the material itself and reduce welding defects. The V-shaped groove is processed by numerical control so that its surface roughness Ra value is not greater than 3.2um, making the manual wire feeding of tungsten inert gas arc welding and the automatic wire feeding of consumable gas arc welding smoother. The welding tooling that can be fixed and preheated can not only control the deformation of the welded parts, but also reasonably control the temperature during welding and reduce the sensitivity of welding cracks. Tungsten inert gas arc welding spot fixation further controls the deformation of the welded parts so that they are always in a good welding state. The 3-layer 4-pass welding method is used for tungsten inert gas arc welding root welding to refine the grain structure of the bottom weld, thereby ensuring the stability of the weld. Consumable gas arc welding filler welding improves efficiency, reduces heat dissipation, effectively controls the temperature between layers, avoids cracks, and at the same time, the transition between the weld and the base material is smooth, reducing stress concentration, so that the weld has excellent mechanical properties and beautiful appearance. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a welding process flow chart of the present invention;

[0043] Figure 2 1. It is a schematic diagram of the weld bead layers of the weld groove and the root welding of the weldment by tungsten inert gas arc welding in an embodiment of the present invention;

[0044] Figure 3 Schematic diagram of welding tooling in an embodiment of the present invention. DETAILED DESCRIPTION

[0045] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions 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. 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.

[0046] Due to the high-strength properties of BS700MCK2 material high-strength steel structural parts, they are highly sensitive to welding cracks. If the process measures are not appropriate during the welding process, the tensile strength of the weld will decrease, and it is also easy to produce defects such as cracks and lack of fusion, leaving great quality risks for product applications.

[0047] In order to prevent the occurrence of welding cracks, the present invention provides a high-strength steel argon arc welding method whose material is BS700MCK2, aiming to realize argon arc welding of this grade of high-strength steel so that the weld has good quality, excellent mechanical properties and beautiful appearance.

[0048] like Figures 1 to 3 As shown, the following steps are included:

[0049] Step 1: Pre-welding preparation, including cleaning the heat-affected zone of the weldment, CNC machining the weldment with a V-shaped groove, and making a set of welding tools that can fix and preheat the weldment;

[0050] Step 2: Install the welded parts in the tooling and fix them with tungsten inert gas arc welding;

[0051] Step 3: Root welding with argon tungsten arc welding;

[0052] Step 4: Apply consumable argon arc welding to fill the welding;

[0053] Step 5: Repair the weld appearance and inspect the weld.

[0054] Through pre-welding preparation, the heat-affected zone is cleaned to ensure the purity of the material itself and reduce welding defects; the V-shaped groove is processed by CNC so that its surface roughness Ra value is not more than 3.2um, making the manual wire feeding of tungsten inert gas arc welding and the automatic wire feeding of consumable gas arc welding smoother; the welding tooling that can be fixed and preheated can not only control the deformation of the welded parts, but also reasonably control the temperature during welding and reduce the sensitivity of welding cracks; the tungsten inert gas arc welding spot fixation further controls the deformation of the welded parts to keep them in a good welding state; the 3-layer 4-pass welding method is used for tungsten inert gas arc welding root welding to refine the grain structure of the underlying weld, thereby ensuring the stability of the weld; finally, the consumable gas arc welding filling welding is used to improve efficiency, reduce heat dissipation, effectively control the interlayer temperature, avoid cracks, and make the weld have excellent mechanical properties and beautiful appearance.

[0055] Pre-welding preparation includes:

[0056] Step 1.1, clean the heat affected zone of the weldment;

[0057] Step 1.2, CNC machining of the V-shaped groove welding parts;

[0058] Step 1.3: Make a set of welding tools that can fix and preheat the welded parts.

[0059] Through pre-welding preparation, the heat-affected zone is cleaned to ensure the purity of the material itself and reduce welding defects; CNC machining of the V-shaped groove makes its surface roughness Ra value no more than 3.2um, making the manual wire feeding of tungsten inert gas arc welding and the automatic wire feeding of consumable inert gas arc welding smoother; the welding tooling that can be fixed and preheated can not only control the deformation of the welded parts, but also reasonably control the temperature during welding and reduce the sensitivity of welding cracks.

[0060] Step 1.1, clean the heat affected zone of the weldment, including the position within 40mm of the heat affected zone of the weldment, use a wire brush to polish it, remove the corrosion pits and rust spots on the surface until the metallic luster is exposed. The 40mm range of the heat affected zone is the position within 40mm around the weld. After cleaning, reduce the contamination of impurities, put the heat affected zone in a good state for welding, and reduce welding defects.

[0061] Step 1.2, CNC machining of V-shaped grooves for welded parts includes CNC machining of a welding groove on the long side of the welded part, single-sided machining, the angle of the groove is 30 degrees, the opposite side of the angle is the thickness direction, the blunt edge is between 0.5mm and 1mm, and the surface roughness Ra value of the groove is not greater than 3.2um. Reasonable groove structure makes manual wire feeding of tungsten inert gas arc welding and automatic wire feeding of consumable inert gas arc welding smoother, which is conducive to improving the quality of the weld and ensuring the appearance of the weld.

[0062] Step 1.3, the welding tooling capable of fixing and preheating the weldment includes a platform for fixing the weldment on the upper side of the tooling, and the pressure plates at both ends can adjust the height by rotating bolts for clamping the weldment. A gap of not less than 80 mm in width is left at the bottom of the tooling. If necessary, a flame spray gun at the bottom of the tooling is used for flame preheating, and the flame spray gun can be manually moved freely along the hole axis direction.

[0063] Step 2: Install the welded parts in the tooling and perform tungsten inert gas arc welding. Spot welding includes:

[0064] Step 2.1, butt-join two welded parts with the dimensions of 6mm×100mm×200mm together, with the 6mm×200mm surface as the contact surface, place them on the fixed platform of the tooling, fasten the pressure plates at both ends with bolts to press the welded parts into the tooling, and then adjust the butt gap of the welded parts to control it within the range of 0 to 0.5mm. The welded parts tooling that can be fixed and preheated can not only control the deformation of the welded parts, but also reasonably control the temperature during welding and reduce the sensitivity of welding cracks.

[0065] Step 2.2, apply tungsten inert gas welding, apply a welding spot every 100mm or so, fast spot welding, the welding spot penetrates the blunt edge, the welding spot length is 2-4mm, the welding angle height is 1-2mm, the welding wire specification is φ2mm, the welding current is 240-280A, the welding voltage is 27V, the shielding gas is 80% Ar and 20% CO2, and the shielding gas flow rate is 20-24L / min. Tungsten inert gas welding spot solidifies and further controls the deformation of the welded parts, so that they are always in a good welding state.

[0066] Step 3: Root welding with argon tungsten arc welding includes:

[0067] Tungsten inert gas welding was used with manual filler wire moving slowly from one side to the other, applying 4 weld passes and welding 3 layers.

[0068] Step 3.1: The first layer of welding includes one weld bead, using low current and slow welding speed to ensure that the blunt edge is fully melted.

[0069] Step 3.2: The second layer of welding includes one weld bead, which is welded with high current, high voltage and fast speed, and the second weld bead is welded while ensuring that the interlayer temperature with the first weld bead is not lower than 150°C.

[0070] Step 3.3: The third layer of welding includes two welds. The welding current, welding voltage and welding speed are consistent with those of the second layer of welding. The third and fourth welds are welded while ensuring that the interlayer temperature of the second weld is not lower than 150°C.

[0071] The three-layer four-pass welding method is used for the root welding of the welded parts, which can refine the grain structure of the bottom weld and ensure the stability of the weld. The thickness of the three-layer weld of tungsten inert gas arc welding is 2 to 3 mm after welding.

[0072] Among them, preferably, in the first layer welding process of tungsten inert gas welding in step 3.1, the welding wire specification is φ2mm, the welding current is 120-160A, the welding voltage is 24V, the welding speed is 100-140mm / min, the shielding gas is a mixture of 80% Ar and 20% CO2, and the shielding gas flow rate is 10-16L / min. Similarly, preferably, in the second and third layers of tungsten inert gas welding in step 3.2, the current is adjusted to 180-220A, the welding voltage is adjusted to 27V, the welding speed is adjusted to 180-240mm / min, and the other welding parameters are consistent with the first layer. The thickness of the three-layer weld is 2-3mm after welding.

[0073] Step 4: Applying consumable argon arc welding to fill the welding process includes:

[0074] Step 4.1: After root welding, ensure that the preheating temperature is between 150℃ and 250℃ to perform consumable argon arc welding filling welding. When the temperature cannot reach the welding conditions, turn on the flame spray gun at the bottom of the tooling for flame preheating. The flame spray gun is manually moved freely along the hole axis to uniformly preheat the weld locally to achieve temperature control.

[0075] Step 4.2, use consumable argon arc welding to slowly move the welding gun from one side to the other side to automatically feed the wire, and use multi-layer and multi-pass welding. Ensure that the interlayer temperature of each layer is not lower than 150℃ before welding the next layer of weld. When welding the last layer, the excess height is controlled between 0.5 and 1.5 mm, and the weld and the base material have a smooth transition. The filling thickness of the consumable argon arc welding weld is 2 to 3 mm.

[0076] Among them, in step 4.1, the uniform local preheating of the weld to achieve temperature control means that based on the weld width of the welded part, a flame spray gun is used to perform local flame heating within a 40mm range around it. Preferably, in the multi-layer and multi-pass welding process of the consumable argon arc welding in step 4.2, the welding wire specification is φ1.2mm, the welding current is 200-240A, the welding voltage is 27V, the welding speed is 220-260mm / min, the shielding gas is 80% Ar and 20% CO2, and the shielding gas flow rate is 16-20L / min. Through the consumable argon arc welding filling high-efficiency welding, heat dissipation is reduced, the interlayer temperature is effectively controlled, and cracks are avoided. At the same time, the transition between the weld and the base material is smooth, stress concentration is reduced, and the weld has excellent mechanical properties and beautiful appearance.

[0077] Step 5: Repair the weld appearance and check the weld bead.

[0078] Use a wire brush or hand grinding wheel to grind the weld, remove the welding slag at the edge of the weld, trim the uneven texture of the weld, improve stress concentration, improve the quality of the weld and beautify the appearance.

[0079] Inspection of welds can be accomplished by testing to demonstrate their structural properties, which may include X-ray inspection and mechanical testing.

[0080] Specifically, in X-ray testing, the weld after arc welding is mainly tested for defects such as cracks, weld bumps, pores, slag inclusions, etc., which meets the requirements of QJ176A Class I quality standard. In mechanical testing, test pieces are cut from welded parts after arc welding and placed on a tensile testing machine for mechanical property testing. The tensile strength of the test piece reaches more than 90% of the lower limit of the tensile strength of the parent material.

[0081] The above-mentioned spot welding, root welding and filling welding all have temperature requirements in the welding process, and the ambient temperature must be >10°C and the humidity must be ≤75%.

[0082] Embodiment: This embodiment provides a argon arc welding method for BS700MCK2 high-strength steel, which aims to ensure excellent weld quality, excellent mechanical properties and beautiful appearance, while effectively preventing the occurrence of welding cracks. The following are the detailed steps of the method:

[0083] Step 1: Preparation before welding

[0084] Clean the heat-affected zone of the weld: Use a wire brush to grind the heat-affected zone of the weld (within 40mm around the weld) to remove corrosion pits, rust spots and other impurities on the surface until the metallic luster is exposed. This step ensures the purity of the welding material and reduces the occurrence of welding defects.

[0085] CNC machining of V-shaped groove: CNC machining of a single-sided V-shaped groove on the long side of the weldment, the groove angle is 30 degrees, the blunt edge is controlled between 0.5mm and 1mm, and the groove surface roughness Ra value is not greater than 3.2um. Reasonable groove structure helps the wire feeding process of tungsten inert gas arc welding and consumable inert gas arc welding to be smoother, thereby improving the quality of the weld.

[0086] Make welding fixture: Make a set of fixtures that can fix and preheat the welded parts. There is a fixed platform on the upper side of the fixture, and the clamps at both ends can be adjusted in height by rotating bolts to clamp the welded parts. A gap of not less than 80mm is left at the bottom of the fixture to facilitate local preheating with a flame spray gun when necessary. The flame spray gun can be manually moved freely along the hole axis to achieve precise temperature control.

[0087] Step 2: Welding parts installation and spot fixing

[0088] Install the weldment: butt-join two weldments of 6mm×100mm×200mm together and place them on the fixed platform of the tooling. Fasten the pressure plates at both ends with bolts to press the weldment into the tooling, and adjust the butt gap of the weldment to within the range of 0 to 0.5mm.

[0089] Tungsten inert gas welding spot fixation: Tungsten inert gas welding is used for spot fixation welding, and a welding spot is applied every 100mm or so. The welding spot needs to penetrate the blunt edge, the length is controlled between 2 and 4mm, and the welding angle height is 1 to 2mm. The welding wire specification is φ2mm, the welding current is 240 to 280A, the welding voltage is 27V, the shielding gas is a mixture of 80% Ar and 20% CO2, and the shielding gas flow rate is 20 to 24L / min. Spot fixation welding helps to further control the deformation of the welded parts.

[0090] Step 3: TIG root welding

[0091] Tungsten inert gas welding was used with manual filler wire moving slowly from one side to the other, with a total of 4 weld passes applied in 3 layers.

[0092] First layer welding: Use low current and slow speed to ensure that the blunt edge is fully melted. The wire specification is φ2mm, the welding current is 120-160A, the welding voltage is 24V, and the welding speed is 100-140mm / min. The shielding gas and flow rate are the same as spot welding.

[0093] Second layer welding: Use high current, high voltage and fast welding. Weld the second weld while ensuring that the interlayer temperature with the first weld is not lower than 150°C. Adjust the welding current to 180-220A, the welding voltage to 27V, and the welding speed to 180-240mm / min. Other welding parameters are the same as the first layer.

[0094] The third layer welding: includes two welds, and the welding parameters are the same as the second layer. The third and fourth welds are welded under the condition that the interlayer temperature of the second weld is not less than 150℃. The thickness of the three-layer weld is 2-3mm after welding.

[0095] Step 4: MIG welding filler welding

[0096] Preheating: After root welding, ensure that the preheating temperature is between 150℃ and 250℃ for MIG welding. If the temperature cannot reach the welding conditions, turn on the flame spray gun at the bottom of the tooling for local preheating. The preheating range is within 40mm around the weld width to ensure uniform temperature.

[0097] Filling welding: Use consumable argon arc welding to slowly move the welding gun from one side to the other side to automatically feed the wire for multi-layer and multi-pass welding. Ensure that the interlayer temperature is not lower than 150℃ when welding each layer. When welding the last layer, the excess height is controlled between 0.5 and 1.5 mm, and the weld and the base material have a smooth transition. The weld filling thickness is 2 to 3 mm. The welding wire specification is φ1.2 mm, the welding current is 200 to 240A, the welding voltage is 27V, and the welding speed is 220 to 260 mm / min. The shielding gas and flow rate are the same as those of tungsten inert gas welding.

[0098] Step 5: Weld seam repair and inspection

[0099] Repair the weld: Use a wire brush or hand grinding wheel to grind the weld to remove the slag and uneven texture at the edge of the weld. This step helps to improve stress concentration, improve weld quality and beautify the appearance.

[0100] Check the weld: Check the weld by X-ray inspection and mechanical test. X-ray inspection mainly checks whether there are cracks, weld bumps, pores, slag inclusions and other defects inside the weld, which must meet the requirements of QJ176A Class I quality standard. The mechanical test is to cut the test piece of the weld and place it on the tensile machine for testing to ensure that the tensile strength of the test piece reaches more than 90% of the lower limit of the tensile strength of the parent material.

[0101] Note:

[0102] The welding process must be carried out under the conditions of ambient temperature >10℃ and humidity ≤75%.

[0103] During spot welding, root welding and filler welding, the temperature must be strictly controlled to meet the welding requirements.

[0104] Through the implementation of the above steps, this embodiment successfully achieves argon arc welding of BS700MCK2 high-strength steel, with excellent weld quality, outstanding mechanical properties and beautiful appearance, and effectively preventing the occurrence of welding cracks.

[0105] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for argon arc welding of high-strength steel with material BS700MCK2, characterized in that: The following steps are involved: Step 1: Pre-welding preparation, including cleaning the heat-affected zone of the weldment, CNC machining the weldment with a V-shaped groove, and making a set of welding tools that can fix and preheat the weldment; Step 2: Install the welded parts in the tooling and fix them with tungsten inert gas arc welding; Step 3: Root welding with argon tungsten arc welding; Step 4: Apply consumable argon arc welding to fill the welding; Step 5: Repair the weld appearance and inspect the weld.

2. The high-strength steel argon arc welding method of BS700MCK2 according to claim 1 is characterized in that: The welding preparation further includes: Use a wire brush to polish the heat-affected zone of the welded parts within 40 mm to remove corrosion pits and rust spots on the surface until the metallic luster is revealed; A single-sided V-shaped groove is CNC machined on the long side of the weldment, with a groove angle of 30 degrees, a blunt edge between 0.5mm and 1mm, and a groove surface roughness Ra value of no more than 3.2um; Make a set of welding tooling. A platform for fixing the welded parts is set on the upper side of the tooling. The height of the pressure plates at both ends can be adjusted by rotating bolts. A gap of not less than 80mm is left at the bottom of the tooling. If necessary, use the flame spray gun at the bottom of the tooling for flame preheating.

3. The method for high-strength steel argon arc welding of BS700MCK2 according to claim 2, characterized in that: The step of installing the welded parts in the tooling and performing tungsten inert gas arc welding on the welded parts further comprises: Two welded parts with the size of 6mm×100mm×200mm are butt-jointed and assembled together, and placed on the fixed platform of the tooling. The pressure plates at both ends are fastened with bolts to press the welded parts into the tooling, and the butt gap of the welded parts is adjusted to the range of 0 to 0.5mm; Tungsten inert gas welding is applied with a weld every 100mm or so, the weld penetrates the blunt edge, the weld length is 2-4mm, the weld angle height is 1-2mm, the welding wire specification is φ2mm, the welding current is 240-280A, the welding voltage is 27V, the shielding gas is 80% Ar and 20% CO2, and the shielding gas flow rate is 20-24L / min.

4. The method for high-strength steel argon arc welding of BS700MCK2 according to claim 1, characterized in that: The root welding of argon tungsten arc welding further comprises: Tungsten inert gas welding was used with manual filler wire moving slowly from one side to the other, with 4 passes applied and 3 layers welded; The first layer of welding is done with low current and slow speed to ensure that the blunt edge is fully melted; The second layer of welding uses high current, high voltage and fast welding, and the interlayer temperature must not be lower than 150℃; The current, voltage and speed of the third layer welding are the same as those of the second layer, and the interlayer temperature must not be lower than 150℃; The thickness of the three-layer weld after welding is 2 to 3 mm.

5. The method for high-strength steel argon arc welding of BS700MCK2 according to claim 4, characterized in that: The specific parameters of the tungsten inert gas arc welding include: During the first layer welding, the welding wire specification is φ2mm, the welding current is 120-160A, the welding voltage is 24V, the welding speed is 100-140mm / min, the shielding gas is a mixture of 80% Ar and 20% CO2, and the shielding gas flow rate is 10-16L / min; During the welding process of the second and third layers, the current was adjusted to 180-220A, the welding voltage was adjusted to 27V, the welding speed was adjusted to 180-240mm / min, and the other welding parameters were the same as those of the first layer.

6. The method for high-strength steel argon arc welding of BS700MCK2 according to claim 1, characterized in that: The argon arc welding filling welding further comprises: When the temperature cannot reach the welding condition, start the flame spray gun at the bottom of the tooling to preheat the local flame. The preheating range is within 40mm around the weld width. Use multi-layer and multi-pass welding to ensure that the interlayer temperature of each layer is not less than 150℃; When welding the last layer, the excess height is controlled between 0.5 and 1.5 mm, the weld and the base material have a smooth transition, and the weld filling thickness is 2 to 3 mm.

7. The method for high-strength steel argon arc welding of BS700MCK2 according to claim 6, characterized in that: The specific parameters of the multi-layer and multi-pass consumable argon arc welding include: The welding wire specification is φ1.2mm, the welding current is 200~240A, the welding voltage is 27V, the welding speed is 220~260mm / min, the shielding gas is 80% Ar and 20% CO2, and the shielding gas flow rate is 16~20L / min.

8. The method for high-strength steel argon arc welding of BS700MCK2 according to claim 1, characterized in that: The repairing of the weld appearance and inspecting the weld bead further comprises: Use a wire brush or hand grinding wheel to grind the weld, remove the welding slag at the edge of the weld, and trim the uneven texture of the weld.

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