Flash welding method for wheel rim based on titanium and manganese alloy strengthening

Abstract

The invention discloses a flash welding method for a wheel rim based on titanium and manganese alloy reinforcement. The flash welding method mainly solves the technical problems that in the welding process of an existing steel wheel rim straight seam based on titanium and manganese alloy reinforcement, the welding seam strength is reduced, and a welding heat affected zone cracks in subsequent machining. According to the technical scheme, the flash welding method for the wheel rim based on titanium and manganese alloy strengthening comprises the steps that (1) a wheel rim blank is prepared, a hot-rolled pickled steel plate with the thickness being 3.0-5.0 mm is rolled to be round and then is in butt joint, and the wheel rim blank is obtained; the metallographic structure of the hot-rolled pickled steel plate is fine grain ferrite and a small amount of pearlite; (2) the wheel rim blank is clamped and fixed; (3) the wheel rim blank is welded; and (4) a welding seam obtained after butt welding of the wheel rim blank is treated. The welding seam gas tightness qualification rate is larger than or equal to 95%, the tensile strength of the welding seam is larger than or equal to 530 MPa, and the welding seam quality is

Description

Technical Field

[0001] The invention relates to a straight seam welding process for a steel wheel rim, in particular to a flash welding method for a wheel rim reinforced with titanium and manganese alloys, specifically to a flash welding method for a straight seam of a steel wheel rim reinforced with titanium and manganese alloys and having a tensile strength of 500 MPa, and belongs to the technical field of steel material welding processing. Background Art

[0002] The automobile industry is developing rapidly, and the consumption of wheels is very huge. China produces more than 30 million steel wheels every year. As the call for environmental protection becomes louder and louder, wheels, as rotating parts of automobiles, still mostly use low-strength steel. The strength, stability and fatigue properties cannot meet the current development needs of the industry. High-strength steel reinforced with Nb and Ti elements is widely used in the automobile industry, but in the process of being promoted to the wheel industry, a high welding defect rate of materials has appeared. The failure of the weld will cause the failure of the entire wheel parts, causing huge safety and economic losses to users. In addition, the price of the alloy element Nb is much higher than that of other alloy elements, so the industry has been developing Ti and Mn alloy element reinforced wheel steel materials that do not contain Nb elements.

[0003] The strength of existing wheel steel reinforced with Ti and Mn alloy elements can reach 500MPa and above, but existing welding process methods cannot produce wheel products with high welding quality; there are problems such as reduced weld strength, cracking during subsequent processing, and poor welding quality.

[0004] The patent application publication number CN107891219A discloses a flash welding process for high-strength ground spike anchor chain, which includes the following steps: (1) Chain link fixing and misalignment correction: The chain link is fixed on a welding machine with a system pressure of 14 to 16 MPa through the joint action of two upper and lower fixed electrodes and two upper and lower movable electrodes, and the upper and lower misalignment of the ring body is corrected. (2) Flash preheating: The left and right electrodes are connected to the secondary of the welding transformer, and a voltage of 4.7V is applied. The welding end faces are quickly contacted and separated once or multiple times to form intermittent flashes. (3) Burning of the welding end faces: After the preheating is completed, a stable continuous flash process is entered, and the movable electrode is advanced at a burning speed of 1.8 to 2.0 mm until the burning amount (i.e., the distance between the left and right electrodes is reduced) of 7 to 9 m is controlled to end. (4) Electric upsetting: After the burning is completed, the power is not turned off immediately. The power is turned off for a period of time during the upsetting process, and sufficient upsetting pressure is applied to the welding end faces. In order to ensure the plastic deformation of the joint, the compression amount of the weld is 6 to 8 mm. (5) Chain link cooling: After the upsetting is completed, the electrode and the upsetting cylinder are kept under pressure for a period of time to ensure that the joint has sufficient deformation resistance and prevent the ring rebound from causing cracking of the welding port. This solves the problem of welding cracking of high-strength anchor chain materials, and the joint performance is stable and meets the requirements; although this process uses flash welding technology, it does not involve the specific process of rim flash welding.

[0005] The prior art lacks effective straight seam welding technology for wheel steel rims reinforced with titanium and manganese alloys. Summary of the invention

[0006] The purpose of the present invention is to provide a flash welding method for a wheel rim reinforced with titanium and manganese alloys, mainly to solve the technical problems that the straight seam of the existing 500MPa-grade steel wheel rim reinforced with titanium and manganese alloys will produce reduced weld strength during the welding process and cracks in the welding heat affected zone during subsequent processing.

[0007] The technical idea of ​​the present invention is to obtain a flat, surface oxide-free, pickled, hot-rolled high-strength wheel steel material reinforced by Ti element through pre-treatment, flash butt welding it, and rolling the high-strength wheel steel material before welding; use flash welding equipment to preheat part of the steel plate between the two electrodes before welding, and flash welding is performed according to set welding process parameters; then top forging is performed on the steel plates between the electrodes with a certain top forging pressure; after welding, the weld is slag-planed, and then the weld is extruded and water-cooled; a wheel product with good welding and no defects such as microcracks and pores in the weld is obtained.

[0008] The technical solution adopted by the present invention is a flash welding method for a wheel rim reinforced with titanium and manganese alloys, comprising the following steps:

[0009] 1) preparing a wheel rim blank, rolling a hot-rolled pickled steel plate with a thickness of 3.0 to 5.0 mm and then butting the hot-rolled pickled steel plate to obtain a wheel rim blank; cleaning the surface of the hot-rolled pickled steel plate to be welded, removing burrs at the cut of the hot-rolled pickled steel plate for the wheel rim, and removing oil stains on the surface of the hot-rolled pickled steel plate to be welded;

[0010] The chemical composition weight percentage of the hot-rolled pickled steel plate is: C: 0.05%-0.07%, Si: 0.10%-0.15%, Mn: 1.25%-1.45%, P≤0.012%, S≤0.003%, Nb: 0.025%-0.035%, Ti: 0.045%-0.055%, Mg: 0.0005%-0.0015%, Al: 0.02%-0.05%, N≤0 .0040%, the rest is Fe and unavoidable impurities, and the content of the above elements must meet the carbon equivalent ≤ 0.35%, wherein the carbon equivalent Ceq = C + Mn / 6, wherein: C, Mn is the weight percentage of the element in the hot-rolled pickled steel plate; the metallographic structure of the hot-rolled pickled steel plate is fine-grained ferrite + a small amount of pearlite, and the ferrite grain size grade in the metallographic structure is 10 to 11 grades; the upper yield strength R of the 3.0 to 5.0 mm thick hot-rolled pickled steel plate eH 350~500MPa, tensile strength R m 500~650MPa, elongation after fracture A is 20%~35%;

[0011] 2) Clamp and fix the wheel rim blank, and fix the wheel rim blank with the clamp of the flash welder; control the gap between the two welding surfaces to be 0.5-1.5mm, and the height difference between the two welding surfaces to be ≤0.5mm; the horizontal distance between the clamps on both sides of the flash welder is 30-50mm;

[0012] 3) The wheel rim blank is welded, and the steel plate welding end face is preheated with a flash welder before welding, and the preheating temperature of the steel plate welding end face is 500-650°C; the straight seam of the wheel rim blank is welded with a flash welder, and the flash allowance is controlled to be 5-10mm, the flash rate is 4-6mm / s, and the flash output power is 150-200KW in the flash stage; the upsetting distance is controlled to be 2-5mm in the upsetting stage; and the pressure is controlled to be 6-8MPa in the pressure holding stage;

[0013] 4) Processing the weld of the wheel rim blank after welding, and immediately performing slagging treatment on the weld; then rolling the weld and water cooling the weld position to obtain a finished wheel rim after welding.

[0014] By adopting the method of the invention, the tensile strength of the weld formed by welding the straight seam of the wheel rim blank is ≥530MPa, and the weld hardness HV0.2 is ≥170.

[0015] By adopting the method of the present invention, the air tightness qualified rate of the weld formed by welding the straight seam of the wheel rim blank is ≥95%; the weld is completely penetrated, the weld surface is evenly formed, the front weld width is 25-30mm, the excess height is 2.0-2.5mm, and the back weld width is 23-28mm, and the excess height is 2.2-2.5mm.

[0016] The reasons for the welding process adopted by the present invention are as follows:

[0017] 1. Setting of clamping parameters of flash welding machine

[0018] The horizontal distance between the clamps on both sides of the flash welder is 30-50mm. If the gap is too small, the preheating temperature of the welding surface will be too high, oxides will be generated on the welding surface, and the welding quality will be affected. If the gap is too large, the steel plates on both sides of the welding surface will be misaligned during the top forging stage. The gap between the two welding surfaces is controlled to be 0.5-1.5mm to ensure the stability of the welding current during the welding process. The height difference between the two welding surfaces is ≤0.5mm to minimize the occurrence of misalignment of the welding surfaces.

[0019] 2. Setting of flash welding parameters

[0020] The Nb element strengthening of existing wheel rims is achieved by refining the grains of the organization, while the Ti element forms Ti compounds that precipitate during the cooling process of the organization to increase the strength of the material. The failure of Ti-reinforced high-strength wheel steel products mainly occurs at the weld position, mainly due to the unreasonable welding process parameters during the welding process, which causes the organization strength to decrease in the heat-affected zone of the weld, thereby causing defects such as shrinkage and cracking of the material in the subsequent processing links. The fundamental reason is that the heat input control during the welding process is improper, resulting in overheating of the heat-affected zone of the weld, and in the subsequent cooling process, the cooling speed of the weld and the heat-affected zone is slow, and the precipitation strengthening effect of the Ti element in the material cannot be achieved, resulting in the strength of the heat-affected zone being lower than that of the parent material.

[0021] The present invention adopts a reasonable welding process, that is, based on a reasonable steel plate extension length, the flash reserve, the flash rate and the welding output power are adjusted, and the welding preheating is performed at a preheating temperature of 500-650°C, so that the welding heat affected zone will not cause the organizational state to change and the strength to decrease due to excessively high temperature. On the other hand, water cooling treatment is performed on the weld immediately after welding is completed, which is also helpful for the heat affected zone organization to maintain the original ferrite + pearlite, and the material strength does not change.

[0022] The present invention sets the preheating temperature to 500-650° C., controls the flash retention to 5-10 mm, the flash rate to 4-6 mm / s, and the flash output power to 150-200 KW in the flash stage; controls the upsetting distance to 2-5 mm in the upsetting stage; and controls the pressure to 6-8 MPa in the pressure holding stage. The welding parameters are used to perform butt welding on Ti and Mn alloy reinforced wheel steel materials, thereby reducing the reduction in weld strength, avoiding the problem of cracking in the welding heat affected zone in subsequent processing, and the problem of poor welding quality.

[0023] Compared with the prior art, the present invention has the following positive effects: 1. The horizontal distance between the clamps on both sides of the flash welding machine adopted by the present invention is 30-50 mm, the gap between the two welding surfaces is controlled to be 0.5-1.5 mm, and the height difference between the two welding surfaces is ≤0.5 mm; it can effectively avoid the problem that the preheating temperature of the welding surface is too high due to the small clamp gap, the generation of oxides on the welding surface, and the welding quality is affected, or the problem that the steel plates on both sides of the welding surface are misaligned during the top forging stage due to the large clamp gap; if the gap between the two welding surfaces is too small, the initial welding current will be large, and if it is too large, the current will be disconnected during the welding process; the height difference between the two welding surfaces is reasonably controlled to reduce the generation of misalignment of the welding surfaces. 2. The preheating temperature is 500-650℃, the flashing amount is controlled to be 5-10mm, the flashing rate is 4-6mm / s, and the flashing output power is 150-200KW; the upsetting distance is controlled to be 2-5mm in the upsetting stage; the pressure is controlled to be 6-8MPa in the pressure holding stage to perform butt welding on Ti and Mn alloy reinforced wheel steel materials. The appropriate post-weld treatment process is adopted to ensure that the material is well welded, the strength in the weld heat affected zone is not reduced, and the weld does not crack during the post-weld processing; the weld is tested for air tightness, and the qualified rate is more than 95%. 3. The technical method of the present invention is simple, the implementation cost is low, and the welding structure and production efficiency are greatly improved. The weld is completely penetrated, the surface is evenly formed, and a weld joint without defects such as microcracks and necking in the weld heat affected zone is obtained. The tensile strength of the weld is ≥530MPa, and the weld hardness HV0.2 is ≥170. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with Examples 1 to 4, as shown in Tables 1 to 2.

[0025] In Examples 1 to 4, the wheel rim blank is made of a hot-rolled pickled steel plate with a thickness of 4.0 mm, and the chemical composition of the hot-rolled steel plate is C: 0.07%, Si: 0.10%, Mn: 1.25%, P: 0.010%, S: 0.0028%, Nb: 0.025%, Ti: 0.045%, Mg: 0.0009%, Al: 0.02%, N: 0.0029%, and the rest is Fe and inevitable impurities, wherein the carbon equivalent Ceq = C + Mn / 6, wherein: C, Mn is the weight percentage of the element in the hot-rolled steel plate; the metallographic structure of the hot-rolled pickled steel plate is fine-grained ferrite + a small amount of pearlite, and the ferrite grain size grade in the metallographic structure is 11; the upper yield strength R of the 4.0 mm thick hot-rolled pickled steel plate is eH The tensile strength R is 370MPa. m It is 510MPa and the elongation after break A is 25%.

[0026] Embodiment 1, a flash welding method for a wheel rim reinforced with titanium and manganese alloys, comprising the following steps:

[0027] 1) preparing a wheel rim blank, rolling a hot-rolled pickled steel plate and then butting the hot-rolled pickled steel plate to obtain a wheel rim blank; cleaning the surface of the hot-rolled pickled steel plate to be welded, removing burrs at the cut of the hot-rolled pickled steel plate for the wheel rim, and removing oil stains on the surface of the hot-rolled pickled steel plate to be welded;

[0028] 2) Clamp and fix the wheel rim blank with the clamp of the flash welder; control the gap between the two welding surfaces to be 1.0mm, and the height difference between the two welding surfaces to be ≤0.5mm; the horizontal distance between the clamps on both sides of the flash welder is 30mm,

[0029] 3) The wheel rim blank is welded. Before welding, the steel plate welding end face is preheated with a flash welder, and the preheating temperature of the steel plate welding end face is 500°C; the straight seam of the wheel rim blank is welded with a flash welder, and the flash allowance is controlled to be 5mm, the flash rate is 4mm / s, and the flash output power is 150KW in the flash stage; the upsetting distance is controlled to be 3.0mm in the upsetting stage; and the pressure is controlled to be 8MPa in the pressure holding stage;

[0030] 4) Processing the weld of the wheel rim blank after welding, and immediately performing slagging treatment on the weld; then rolling the weld and water cooling the weld position to obtain a finished wheel rim after welding.

[0031] After welding, the weld joints were visually inspected and the welds were completely penetrated, the weld surface was evenly formed, the front weld width was 25-30mm, the excess height was 2.0-2.5mm, the back weld width was 23-28mm, and the excess height was 2.2-2.5mm. The weld joints were tested for air tightness and no quality defects such as leakage were found.

[0032] Embodiment 2, a flash welding method for a wheel rim reinforced with titanium and manganese alloys, comprising the following steps:

[0033] 1) preparing a wheel rim blank, rolling a hot-rolled pickled steel plate and then butting the hot-rolled pickled steel plate to obtain a wheel rim blank; cleaning the surface of the hot-rolled pickled steel plate to be welded, removing burrs at the cut of the hot-rolled pickled steel plate for the wheel rim, and removing oil stains on the surface of the hot-rolled pickled steel plate to be welded;

[0034] 2) Clamp and fix the wheel rim blank with the clamp of the flash welder; control the gap between the two welding surfaces to be 1.0mm, and the height difference between the two welding surfaces to be ≤0.5mm; the horizontal distance between the clamps on both sides of the flash welder is 34mm,

[0035] 3) The wheel rim blank is welded. Before welding, the steel plate welding end face is preheated with a flash welder, and the preheating temperature of the steel plate welding end face is 550°C; the straight seam of the wheel rim blank is welded with a flash welder, and the flash allowance is controlled to be 7mm, the flash rate is 5mm / s, and the flash output power is 170KW in the flash stage; the upsetting distance is controlled to be 3.0mm in the upsetting stage; and the pressure is controlled to be 8MPa in the pressure holding stage;

[0036] 4) Processing the weld of the wheel rim blank after welding, and immediately performing slagging treatment on the weld; then rolling the weld and water cooling the weld position to obtain a finished wheel rim after welding.

[0037] After welding, the weld joints were visually inspected and the welds were completely penetrated, the weld surface was evenly formed, the front weld width was 25-30mm, the excess height was 2.0-2.5mm, the back weld width was 23-28mm, and the excess height was 2.2-2.5mm. The weld joints were tested for air tightness and no quality defects such as leakage were found.

[0038] Embodiment 3, a flash welding method for a wheel rim reinforced with titanium and manganese alloys, comprising the following steps:

[0039] 1) preparing a wheel rim blank, rolling a hot-rolled pickled steel plate and then butting the hot-rolled pickled steel plate to obtain a wheel rim blank; cleaning the surface of the hot-rolled pickled steel plate to be welded, removing burrs at the cut of the hot-rolled pickled steel plate for the wheel rim, and removing oil stains on the surface of the hot-rolled pickled steel plate to be welded;

[0040] 2) Clamp and fix the wheel rim blank with the clamp of the flash welder; control the gap between the two welding surfaces to be 1.0mm, and the height difference between the two welding surfaces to be ≤0.5mm; the horizontal distance between the clamps on both sides of the flash welder is 40mm,

[0041] 3) The wheel rim blank is welded. Before welding, the steel plate welding end face is preheated with a flash welder, and the preheating temperature of the steel plate welding end face is 600°C; the straight seam of the wheel rim blank is welded with a flash welder, and the flash allowance is controlled to be 10mm, the flash rate is 5mm / s, and the flash output power is 200KW in the flash stage; the upsetting distance is controlled to be 3.0mm in the upsetting stage; and the pressure is controlled to be 8MPa in the pressure holding stage;

[0042] 4) Processing the weld of the wheel rim blank after welding, and immediately performing slagging treatment on the weld; then rolling the weld and water cooling the weld position to obtain a finished wheel rim after welding.

[0043] After welding, the weld joints were visually inspected and the welds were completely penetrated, the weld surface was evenly formed, the front weld width was 25-30mm, the excess height was 2.0-2.5mm, the back weld width was 23-28mm, and the excess height was 2.2-2.5mm. The weld joints were tested for air tightness and no quality defects such as leakage were found.

[0044] Embodiment 4, a flash welding method for a wheel rim reinforced with titanium and manganese alloys, comprising the following steps:

[0045] 1) preparing a wheel rim blank, rolling a hot-rolled pickled steel plate and then butting the hot-rolled pickled steel plate to obtain a wheel rim blank; cleaning the surface of the hot-rolled pickled steel plate to be welded, removing burrs at the cut of the hot-rolled pickled steel plate for the wheel rim, and removing oil stains on the surface of the hot-rolled pickled steel plate to be welded;

[0046] 2) Clamp and fix the wheel rim blank with the clamp of the flash welder; control the gap between the two welding surfaces to be 1.0mm, and the height difference between the two welding surfaces to be ≤0.5mm; the horizontal distance between the clamps on both sides of the flash welder is 50mm,

[0047] 3) The wheel rim blank is welded. Before welding, the steel plate welding end face is preheated with a flash welder, and the preheating temperature of the steel plate welding end face is 650°C; the straight seam of the wheel rim blank is welded with a flash welder, and the flash allowance is controlled to be 10mm, the flash rate is 6mm / s, and the flash output power is 200KW in the flash stage; the upsetting distance is controlled to be 3.0mm in the upsetting stage; and the pressure is controlled to be 8MPa in the pressure holding stage;

[0048] 4) Processing the weld of the wheel rim blank after welding, and immediately performing slagging treatment on the weld; then rolling the weld and water cooling the weld position to obtain a finished wheel rim after welding.

[0049] After welding, the weld joints were visually inspected and the welds were completely penetrated, the weld surface was evenly formed, the front weld width was 25-30mm, the excess height was 2.0-2.5mm, the back weld width was 23-28mm, and the excess height was 2.2-2.5mm. The weld joints were tested for air tightness and no quality defects such as leakage were found.

[0050] The straight butt seam of the wheel rim blank welded by the method of the present invention has high strength, the weld has no obvious cracks and pores, the two sides of the weld are firmly bonded, the tensile strength of the weld is ≥530MPa, and the weld hardness HV0.2 is ≥170, which meets the requirements for stable operation of the wheel.

[0051] Table 1 Welding control parameters of the embodiment of the present invention

[0052]

[0053] Table 2 Weld quality data of the embodiment of the present invention

[0054]

[0055]

[0056] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A flash welding method for a wheel rim reinforced with titanium and manganese alloys, characterized in that: The method comprises the following steps: 1) preparing a wheel rim blank, rolling a hot-rolled pickled steel plate with a thickness of 3.0 to 5.0 mm and then butting the hot-rolled pickled steel plate to obtain a wheel rim blank; cleaning the surface of the hot-rolled pickled steel plate to be welded, removing burrs at the cut of the hot-rolled pickled steel plate for the wheel rim, and removing oil stains on the surface of the hot-rolled pickled steel plate to be welded; The chemical composition weight percentage of the hot-rolled pickled steel plate is: C: 0.05%-0.07%, Si: 0.10%-0.15%, Mn: 1.25%-1.45%, P≤0.012%, S≤0.003%, Nb: 0.025%-0.035%, Ti: 0.045%-0.055%, Mg: 0.0005%-0.0015%, Al: 0.02%-0.05%, N≤0 .0040%, the rest is Fe and unavoidable impurities, and the content of the above elements must meet the carbon equivalent ≤ 0.35%, wherein the carbon equivalent Ceq = C + Mn / 6, wherein: C, Mn is the weight percentage of the element in the hot-rolled pickled steel plate; the metallographic structure of the hot-rolled pickled steel plate is fine-grained ferrite + a small amount of pearlite, and the ferrite grain size grade in the metallographic structure is 10 to 11 grades; the upper yield strength R of the 3.0 to 5.0 mm thick hot-rolled pickled steel plate eH 350~500MPa, tensile strength R m 500~650MPa, elongation after fracture A is 20%~35%; 2) Clamp and fix the wheel rim blank, and fix the wheel rim blank with the clamp of the flash welder; control the gap between the two welding surfaces to be 0.5-1.5mm, and the height difference between the two welding surfaces to be ≤0.5mm; the horizontal distance between the clamps on both sides of the flash welder is 30-50mm; 3) The wheel rim blank is welded, and the steel plate welding end face is preheated with a flash welder before welding, and the preheating temperature of the steel plate welding end face is 500-650°C; the straight seam of the wheel rim blank is welded with a flash welder, and the flash allowance is controlled to be 5-10mm, the flash rate is 4-6mm / s, and the flash output power is 150-200KW in the flash stage; the upsetting distance is controlled to be 2-5mm in the upsetting stage; and the pressure is controlled to be 6-8MPa in the pressure holding stage; 4) Processing the weld of the wheel rim blank after welding, and immediately performing slagging treatment on the weld; then rolling the weld and water cooling the weld position to obtain a finished wheel rim after welding.

2. The flash welding method for a wheel rim reinforced with titanium and manganese alloys as claimed in claim 1, characterized in that: The tensile strength of the weld formed by straight welding of the wheel rim blank shall be ≥530MPa, and the weld hardness HV0.2 shall be ≥170.

3. The flash welding method for a wheel rim reinforced with titanium and manganese alloys as claimed in claim 1, characterized in that: The qualified rate of air tightness of the weld formed by welding the straight seam of the wheel rim blank is ≥95%; the front weld width is 25-30mm, the excess height is 2.0-2.5mm, the back weld width is 23-28mm, and the excess height is 2.2-2.5mm.

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