Narrow lap welding method for 590MPa-grade cold-rolled dual-phase steel and 280-320MPa-strength IF steel

Abstract

The invention discloses a narrow lap joint welding method for 590 MPa-grade cold-rolled dual-phase steel and 280-320 MPa-strength IF steel, and relates to the technical field of cold-rolled strip steel welding.The narrow lap joint welding method for the 590 MPa-grade cold-rolled dual-phase steel and the 280-320 MPa-strength IF steel comprises the following steps that the welding position of welding base metal is subjected to pre-welding treatment; after the welding treatment is completed, narrow lap welding is carried out on the welding base metal, wherein the narrow lap welding parameters are as follows: the welding current is 15-20 kA; the welding speed is 6-10 m / min; the pressure of the welding wheel is 16-20 kN; the welding overlap amount ranges from 1.5 mm to 2.0 mm; the welding compensation amount ranges from 1.0 mm to 1.5 mm, base metal for welding is strip steel, and the thickness of the strip steel ranges from 0.5 mm to 2.0 mm. The cold-rolled dual-phase steel strip and IF steel provided by the invention have high weld strength, very high plasticity and toughness, and do not have the phenomena of open welding, fracture and the like after multiple times of steering, reverse bending and high-temperature heat preservation on a large-tension production line, thereby avoiding the occurrence of weld strip breakage accidents and ensuring the safe production of the production line.

Description

Technical Field

[0001] The invention relates to the technical field of cold-rolled strip steel welding, in particular to a narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel. Background Art

[0002] In the continuous annealing or hot-dip galvanizing unit, a narrow lap welder is used to connect the tail of the preceding strip and the head of the following strip to ensure the continuous operation of the production line. Narrow lap welding is a type of resistance welding, which is a welding method that presses the workpiece to be welded between two electrodes and uses the resistance heat effect generated by the current flowing through the contact surface and adjacent areas of the workpiece to heat it to a molten or plastic state to form a metal bond. The narrow lap welder's guarantee of strip welding quality is an important guarantee for capacity expansion and determines the stable operation of high-strength automotive plates under high temperature and high tension conditions.

[0003] DP dual-phase steel is generally produced with mild steel (CQ) as the transition welding material. Since DP steel needs to be cooled quickly in the rapid cooling stage to form martensite structure, the P9-P12 temperature is very low, only 280-300℃, which is far lower than the annealing P9-P12 temperature of mild steel (380-400℃). In order to ensure the temperature of the cold-rolled DP steel aging stage, more transition materials are required. Generally, at least 3-4 rolls of mild steel are required before and after the DP steel for transition, resulting in a large number of downgrades due to unqualified transition material temperature. On average, about 300 tons of DP steel are downgraded due to temperature transition each month, which has a great impact on quality indicators. IF steel has no aging and no requirements for aging temperature. IF steel and DP steel are used for welding transition to avoid degradation caused by temperature transition.

[0004] However, in China, there are many articles published on laser welding for the welding process of high-strength steel for automobiles above 800MPa, while the research on narrow lap resistance welding is mainly concentrated between the same high-strength steels, and the research on welding of dissimilar steels is also mainly concentrated between stainless steel and low-carbon steel. There are few reports on the welding problems between high-strength steel plates for automobiles and ordinary carbon steel plates and IF steels for deep drawing.

[0005] In order to solve the welding problem between cold-rolled dual-phase steel and IF steel, a narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel is proposed. Summary of the invention

[0006] The object of the present invention is to provide a narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel, so as to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions: A narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel, the narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel comprising the following steps: Carry out pre-welding treatment on the welding position of the welding base material; After the welding process is completed, narrow lap welding is performed on the welding base material, wherein the narrow lap welding parameters are: welding current is 15-20kA; welding speed is 6-10m / min; welding wheel pressure is 16-20kN; welding overlap is 1.5-2.0mm; welding compensation is 1.0-1.5mm, and the base materials for welding are all strip steel with a strip thickness of 0.5-2.0mm.

[0008] As a further solution of the present invention: the narrow lap welding parameters are: welding current of 16-19kA; welding speed of 7-9m / min; welding wheel pressure of 17-19kN; welding overlap of 1.6-1.9mm; welding compensation of 1.1-1.4mm, and the base materials for welding are all strip steel with a thickness of 0.8-1.8mm.

[0009] As a further solution of the present invention: the narrow lap welding parameters are: welding current is 17kA; welding speed is 8m / min; welding wheel pressure is 18kN; welding overlap is 1.8mm; welding compensation is 1.3mm, and the base materials for welding are all strip steel with a strip thickness of 1.2mm.

[0010] As a further solution of the present invention: 4. The thickness of the two strips to be welded should meet the following requirements: If the thickness of the two strips is less than 0.65mm, the difference in thickness between the two strips is less than or equal to 0.1mm; If the thickness of the two strips is greater than or equal to 0.65 mm and less than or equal to 0.8 mm, the difference in thickness between the two strips is less than or equal to 0.15 mm; If the thickness of the two strips is greater than or equal to 0.8 mm and less than or equal to 1.5 mm, the thickness ratio between the two strips is less than or equal to 1.3; If the thickness of the two steel strips is greater than or equal to 1.5 mm, the difference in thickness between the two steel strips is less than or equal to 0.4 mm.

[0011] As a further solution of the present invention: the pre-welding treatment includes cleaning the welding position by a mechanical cleaning method.

[0012] As a further solution of the present invention: the mechanical cleaning method includes rubbing and brushing the surface of the weldment using tools such as a grinding wheel or a wire brush.

[0013] As a further solution of the present invention: the mass percentage of the main chemical components of the dual-phase steel is: C: 0.07-0.11%, Si: 0.33-0.48%, Mn: 1.65-1.75%, Si: <1%, and the rest are Fe and unavoidable impurity elements.

[0014] As a further solution of the present invention: the mass percentage of the main chemical components of the dual-phase steel is: C: 0.09%, Si: 0.40%, Mn: 1.70%, Si: <0.6%, and the rest are Fe and unavoidable impurity elements.

[0015] As a further solution of the present invention: the mass percentage of the main chemical components of IF steel is: C: 0.003-0.005%, N: 0.002-0.003%, Ti or Nb about 0.04-0.05%, and the rest is Fe and unavoidable impurity elements.

[0016] As a further solution of the present invention: the mass percentage of the main chemical components of IF steel is: C: 0.004%, N: <0.0025%, Ti or Nb about 0.045%, and the rest is Fe and unavoidable impurity elements.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: the cold-rolled dual-phase steel strip and IF steel welds of the present invention have high strength, and have very high plasticity and toughness. They will not cause open welding, breakage, etc. when undergoing multiple turns, reverse bending, and high-temperature insulation on a high-tension production line, thereby avoiding the occurrence of weld breakage accidents and ensuring safe production of the production line. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a diagram of the weld joint structure before heat treatment in an embodiment of the present invention.

[0019] Figure 2 This is a diagram of the weld joint structure after heat treatment in an embodiment of the present invention.

[0020] Figure 3 This is a weld cupping test diagram of Example 6 of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in 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.

[0022] The present invention provides a narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel, and the narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel comprises: S1. Perform pre-welding treatment on the welding position of the welding base material; In some embodiments, the pre-welding treatment includes cleaning the welding location using a mechanical cleaning method.

[0023] In some embodiments, the mechanical cleaning method includes rubbing and brushing the surface of the weldment using a tool such as a grinding wheel or a wire brush to remove oxide scale and rust on the surface.

[0024] S2. After the welding process is completed, narrow lap welding is performed on the welding base material, wherein the narrow lap welding parameters are: welding current is 15-20kA; welding speed is 6-10m / min; welding wheel pressure is 16-20kN; welding overlap is 1.5-2.0mm; welding compensation is 1.0-1.5mm, and the base material for welding is all strip steel with a strip thickness of 0.5-2.0mm.

[0025] In some embodiments, after the S2 welding process is completed, narrow lap welding is performed on the welding base material, wherein the narrow lap welding parameters are: welding current is 16-19kA; welding speed is 7-9m / min; welding wheel pressure is 17-19kN; welding lap amount is 1.6-1.9mm; welding compensation amount is 1.1-1.4mm, and the base materials for welding are all strip steel, and the strip steel thickness is 0.8-1.8mm.

[0026] After the S2 welding process is completed, narrow lap welding is performed on the welding base material, wherein the narrow lap welding parameters are: welding current is 17kA; welding speed is 8m / min; welding wheel pressure is 18kN; welding overlap is 1.8mm; welding compensation is 1.3mm, and the base materials for welding are all strip steel with a strip steel thickness of 1.2mm.

[0027] S3. Heat treat the welded parts.

[0028] like Figure 1 and 2 As shown, the microstructure of the weld joint after welding of the present invention: the weld zone can be divided into two parts, the DC04 side is ferrite, the DP590 side is blocky martensite, the heat-affected zone on the DP590 side is fine ferrite + martensite, and the heat-affected zone on the DC04 side is larger ferrite. After heat treatment, the weld joint is ferrite on the DC04 side, and the heat-affected zone on the DP590 side is ferrite + pearlite.

[0029] The mechanical properties of the welded joint of the present invention are shown in Table 1 below: Table 1. Mechanical properties of welded joints

[0030] In some embodiments, the thickness of the two strips of steel to be welded should meet the following requirements: If the thickness of the two strips is less than 0.65mm, the difference in thickness between the two strips is less than or equal to 0.1mm; If the thickness of the two strips is greater than or equal to 0.65 mm and less than or equal to 0.8 mm, the difference in thickness between the two strips is less than or equal to 0.15 mm; If the thickness of the two strips is greater than or equal to 0.8 mm and less than or equal to 1.5 mm, the thickness ratio between the two strips is less than or equal to 1.3; If the thickness of the two steel strips is greater than or equal to 1.5 mm, the difference in thickness between the two steel strips is less than or equal to 0.4 mm.

[0031] In some embodiments, the mass percentages of the main chemical components of the dual-phase steel are: C: 0.07-0.11%, Si: 0.33-0.48%, Mn: 1.65-1.75%, Si: <1%, and the rest are Fe and unavoidable impurity elements.

[0032] In some embodiments, the mass percentages of the main chemical components of the dual-phase steel are: C: 0.08-0.10%, Si: 0.35-0.43%, Mn: 1.68-1.72%, Si: <0.8%, and the rest are Fe and unavoidable impurity elements.

[0033] In some embodiments, the mass percentages of the main chemical components of the dual-phase steel are: C: 0.09%, Si: 0.40%, Mn: 1.70%, Si: <0.6%, and the rest are Fe and unavoidable impurity elements.

[0034] In some embodiments, the mass percentages of the main chemical components of IF steel are: C: 0.003-0.005%, N: 0.002-0.003%, Ti or Nb about 0.04-0.05%, and the rest are Fe and unavoidable impurity elements.

[0035] In some embodiments, the mass percentages of the main chemical components of IF steel are: C: 0.0035-0.0045%, N: 0.0023-0.0027%, Ti or Nb about 0.042-0.048%, and the rest are Fe and unavoidable impurity elements.

[0036] In some embodiments, the mass percentages of the main chemical components of IF steel are: C: 0.004%, N: <0.0025%, Ti or Nb about 0.045%, and the rest are Fe and unavoidable impurity elements.

[0037] It should be noted that IF steel, the full name of which is Interstitial-Free Steel, is interstitial-free steel, sometimes also called ultra-low carbon steel. It has extremely excellent deep drawing performance, and its elongation and r value can now reach 50% and above 2.0, and has been widely used in the automotive industry. In IF steel, due to the low content of C and N, a certain amount of strong carbonitride forming elements such as titanium (Ti) and niobium (Nb) are added to completely fix the interstitial atoms such as carbon and nitrogen in the ultra-low carbon steel into carbonitride compounds, thereby obtaining clean ferrite steel without interstitial atoms, which is ultra-low carbon interstitial-free steel.

[0038] The cold-rolled dual-phase steel strip and IF steel weld of the present invention has high strength, high plasticity and toughness, and will not cause welding or fracture when subjected to multiple turns, reverse bending and high-temperature insulation on a high-tension production line, thereby avoiding the occurrence of weld break accidents and ensuring safe production of the production line.

[0039] Example 1 A narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel, the narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel comprising: S1. Perform pre-welding treatment on the welding position of the welding base material; In some embodiments, the pre-welding treatment includes cleaning the welding location using a mechanical cleaning method.

[0040] In some embodiments, the mechanical cleaning method includes rubbing and brushing the surface of the weldment using a tool such as a grinding wheel or a wire brush to remove oxide scale and rust on the surface.

[0041] S2. After the welding process is completed, narrow lap welding is performed on the welding base material, wherein the narrow lap welding parameters are: welding current is 20kA; welding speed is 10m / min; welding wheel pressure is 20kN; welding lap amount is 2.0mm; welding compensation amount is 1.5mm, and the base materials for welding are all strip steel, and the strip steel thickness is 2.0mm.

[0042] S3. Heat treat the welded parts.

[0043] In some embodiments, the thickness of the two strips of steel to be welded should meet the following requirements: If the thickness of the two strips is less than 0.65mm, the difference in thickness between the two strips is less than or equal to 0.1mm; If the thickness of the two strips is greater than or equal to 0.65 mm and less than or equal to 0.8 mm, the difference in thickness between the two strips is less than or equal to 0.15 mm; If the thickness of the two strips is greater than or equal to 0.8 mm and less than or equal to 1.5 mm, the thickness ratio between the two strips is less than or equal to 1.3; If the thickness of the two steel strips is greater than or equal to 1.5 mm, the difference in thickness between the two steel strips is less than or equal to 0.4 mm.

[0044] In some embodiments, the mass percentages of the main chemical components of the dual-phase steel are: C: 0.11%, Si: 0.48%, Mn: 1.75%, Si: <1%, and the rest are Fe and unavoidable impurity elements.

[0045] In some embodiments, the mass percentages of the main chemical components of IF steel are: C: 0.005%, N: 0.003%, Ti or Nb about 0.05%, and the rest are Fe and unavoidable impurity elements.

[0046] Example 2 A narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel, the narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel comprising: S1. Perform pre-welding treatment on the welding position of the welding base material; In some embodiments, the pre-welding treatment includes cleaning the welding location using a mechanical cleaning method.

[0047] In some embodiments, the mechanical cleaning method includes rubbing and brushing the surface of the weldment using a tool such as a grinding wheel or a wire brush to remove oxide scale and rust on the surface.

[0048] S2. After the welding process is completed, narrow lap welding is performed on the welding base material, wherein the narrow lap welding parameters are: welding current is 15kA; welding speed is 6m / min; welding wheel pressure is 16kN; welding overlap is 1.5mm; welding compensation is 1.0mm, and the base materials for welding are all strip steel with a strip thickness of 0.5mm.

[0049] S3. Heat treat the welded parts.

[0050] In some embodiments, the thickness of the two strips of steel to be welded should meet the following requirements: If the thickness of the two strips is less than 0.65mm, the difference in thickness between the two strips is less than or equal to 0.1mm; If the thickness of the two strips is greater than or equal to 0.65 mm and less than or equal to 0.8 mm, the difference in thickness between the two strips is less than or equal to 0.15 mm; If the thickness of the two strips is greater than or equal to 0.8 mm and less than or equal to 1.5 mm, the thickness ratio between the two strips is less than or equal to 1.3; If the thickness of the two steel strips is greater than or equal to 1.5 mm, the difference in thickness between the two steel strips is less than or equal to 0.4 mm.

[0051] The mass percentages of the main chemical components of the dual-phase steel are: C: 0.07%, Si: 0.33%, Mn: 1.65%, Si: <1%, and the rest are Fe and unavoidable impurity elements.

[0052] In some embodiments, the mass percentages of the main chemical components of IF steel are: C: 0.003%, N: 0.002%, Ti or Nb about 0.04%, and the rest are Fe and unavoidable impurity elements.

[0053] Example 3 A narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel, the narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel comprising: S1. Perform pre-welding treatment on the welding position of the welding base material; The pre-welding treatment includes cleaning the welding position by a mechanical cleaning method.

[0054] The mechanical cleaning method includes rubbing and brushing the surface of the weldment using a grinding wheel or a wire brush to remove oxide scale and rust on the surface.

[0055] S2. After the welding process is completed, narrow lap welding is performed on the welding base material, wherein the narrow lap welding parameters are: welding current is 19kA; welding speed is 9m / min; welding wheel pressure is 19kN; welding lap amount is 1.9mm; welding compensation amount is 1.4mm, and the base materials for welding are all strip steel, and the strip steel thickness is 1.8mm.

[0056] S3. Heat treat the welded parts.

[0057] In some embodiments, the thickness of the two strips of steel to be welded should meet the following requirements: If the thickness of the two strips is less than 0.65mm, the difference in thickness between the two strips is less than or equal to 0.1mm; If the thickness of the two strips is greater than or equal to 0.65 mm and less than or equal to 0.8 mm, the difference in thickness between the two strips is less than or equal to 0.15 mm; If the thickness of the two strips is greater than or equal to 0.8 mm and less than or equal to 1.5 mm, the thickness ratio between the two strips is less than or equal to 1.3; If the thickness of the two steel strips is greater than or equal to 1.5 mm, the difference in thickness between the two steel strips is less than or equal to 0.4 mm.

[0058] The mass percentages of the main chemical components of the dual-phase steel are: C: 0.10%, Si: 0.43%, Mn: 1.72%, Si: <0.8%, and the rest are Fe and unavoidable impurity elements.

[0059] The mass percentage of the main chemical components of IF steel is: C: 0.0045%, N: 0.0027%, Ti or Nb about 0.048%, and the rest is Fe and unavoidable impurity elements.

[0060] Example 4 A narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel, the narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel comprising: S1. Perform pre-welding treatment on the welding position of the welding base material; The pre-welding treatment includes cleaning the welding position by a mechanical cleaning method.

[0061] The mechanical cleaning method includes rubbing and brushing the surface of the weldment using a grinding wheel or a wire brush to remove oxide scale and rust on the surface.

[0062] S2. After the welding process is completed, narrow lap welding is performed on the welding base material, wherein the narrow lap welding parameters are: welding current is 16kA; welding speed is 7m / min; welding wheel pressure is 17kN; welding lap amount is 1.6mm; welding compensation amount is 1.1mm, and the base materials for welding are all strip steel, and the strip steel thickness is 0.8mm.

[0063] S3. Heat treat the welded parts.

[0064] In some embodiments, the thickness of the two strips of steel to be welded should meet the following requirements: If the thickness of the two strips is less than 0.65mm, the difference in thickness between the two strips is less than or equal to 0.1mm; If the thickness of the two strips is greater than or equal to 0.65 mm and less than or equal to 0.8 mm, the difference in thickness between the two strips is less than or equal to 0.15 mm; If the thickness of the two strips is greater than or equal to 0.8 mm and less than or equal to 1.5 mm, the thickness ratio between the two strips is less than or equal to 1.3; If the thickness of the two steel strips is greater than or equal to 1.5 mm, the difference in thickness between the two steel strips is less than or equal to 0.4 mm.

[0065] The mass percentages of the main chemical components of the dual-phase steel are: C: 0.08%, Si: 0.35%, Mn: 1.68%, Si: <0.8%, and the rest are Fe and unavoidable impurity elements.

[0066] The mass percentage of the main chemical components of IF steel is: C: 0.0035%, N: 0.0023%, Ti or Nb about 0.042%, and the rest is Fe and unavoidable impurity elements.

[0067] Example 5 A narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel, the narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel comprising: S1. Perform pre-welding treatment on the welding position of the welding base material; The pre-welding treatment includes cleaning the welding position by a mechanical cleaning method.

[0068] The mechanical cleaning method includes rubbing and brushing the surface of the weldment using a grinding wheel or a wire brush to remove oxide scale and rust on the surface.

[0069] S2. After the welding process is completed, narrow lap welding is performed on the welding base material, wherein the narrow lap welding parameters are: welding current is 17kA; welding speed is 8m / min; welding wheel pressure is 18kN; welding overlap is 1.8mm; welding compensation is 1.3mm, and the base materials for welding are all strip steel with a strip thickness of 1.2mm.

[0070] S3. Heat treat the welded parts.

[0071] In some embodiments, the thickness of the two strips of steel to be welded should meet the following requirements: If the thickness of the two strips is less than 0.65mm, the difference in thickness between the two strips is less than or equal to 0.1mm; If the thickness of the two strips is greater than or equal to 0.65 mm and less than or equal to 0.8 mm, the difference in thickness between the two strips is less than or equal to 0.15 mm; If the thickness of the two strips is greater than or equal to 0.8 mm and less than or equal to 1.5 mm, the thickness ratio between the two strips is less than or equal to 1.3; If the thickness of the two steel strips is greater than or equal to 1.5 mm, the difference in thickness between the two steel strips is less than or equal to 0.4 mm.

[0072] The mass percentages of the main chemical components of the dual-phase steel are: C: 0.09%, Si: 0.40%, Mn: 1.70%, Si: <0.6%, and the rest are Fe and unavoidable impurity elements.

[0073] The mass percentage of the main chemical components of IF steel is: C: 0.004%, N: 0.0025%, Ti or Nb about 0.045%, and the rest is Fe and unavoidable impurity elements.

[0074] Example 6 A narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel, the narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel comprising: S1. Perform pre-welding treatment on the welding position of the welding base material; The pre-welding treatment includes cleaning the welding position by a mechanical cleaning method.

[0075] The mechanical cleaning method includes rubbing and brushing the surface of the weldment using a grinding wheel or a wire brush to remove oxide scale and rust on the surface.

[0076] S2. After the welding process is completed, narrow lap welding is performed on the welding base material, wherein the narrow lap welding parameters are: welding current is 17kA; welding speed is 8m / min; welding wheel pressure is 18kN; welding overlap is 1.5mm; welding compensation is 1mm, and the pressure wheel pressure is 2.0KN.

[0077] S3. Heat treat the welded parts.

[0078] In some embodiments, the thickness of the two strips of steel to be welded should meet the following requirements: If the thickness of the two strips is less than 0.65mm, the difference in thickness between the two strips is less than or equal to 0.1mm; If the thickness of the two strips is greater than or equal to 0.65 mm and less than or equal to 0.8 mm, the difference in thickness between the two strips is less than or equal to 0.15 mm; If the thickness of the two strips is greater than or equal to 0.8 mm and less than or equal to 1.5 mm, the thickness ratio between the two strips is less than or equal to 1.3; If the thickness of the two steel strips is greater than or equal to 1.5 mm, the difference in thickness between the two steel strips is less than or equal to 0.4 mm.

[0079] The mass percentages of the main chemical components of 590DP and DC04 are shown in Table 2: Table 2 shows the mass percentage of the main chemical components of 590DP and DC04

[0080] Carbon equivalent Ceq= [C+Mn / 6+(Cr+Mo+V) / 5+(Ni+Cu) / 15]*100%.

[0081] Table 3 Mechanical properties of welding base metal

[0082] Performance testing like Figure 3As shown, the specimen of Example 6 passed the cupping test, the crack and the weld line were perpendicular, and the weld quality was qualified.

[0083] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A narrow lap welding method for 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel, characterized in that: The narrow lap welding method of the 590MPa grade cold-rolled dual-phase steel and the 280-320MPa strength IF steel comprises the following steps: Carry out pre-welding treatment on the welding position of the welding base material; After the welding process is completed, narrow lap welding is performed on the welding base material, wherein the narrow lap welding parameters are: welding current is 15-20kA; welding speed is 6-10m / min; welding wheel pressure is 16-20kN; welding overlap is 1.5-2.0mm; welding compensation is 1.0-1.5mm, and the base materials for welding are all strip steel with a strip thickness of 0.5-2.0mm.

2. The narrow lap welding method of 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel according to claim 1, characterized in that: The narrow lap welding parameters are: welding current is 16~19kA; welding speed is 7~9m / min; welding wheel pressure is 17~19kN; welding overlap is 1.6~1.9mm; welding compensation is 1.1~1.4mm. The base materials for welding are all strip steel with a thickness of 0.8~1.8mm.

3. The narrow lap welding method of 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel according to claim 1, characterized in that: The narrow lap welding parameters are: welding current is 17kA; welding speed is 8m / min; welding wheel pressure is 18kN; welding overlap is 1.8mm; welding compensation is 1.3mm. The base materials for welding are all strip steel with a thickness of 1.2mm.

4. The narrow lap welding method of 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel according to claim 1, characterized in that: The thickness of the two strips to be welded shall meet the following requirements: If the thickness of the two strips is less than 0.65mm, the difference in thickness between the two strips is less than or equal to 0.1mm; If the thickness of the two strips is greater than or equal to 0.65 mm and less than or equal to 0.8 mm, the difference in thickness between the two strips is less than or equal to 0.15 mm; If the thickness of the two strips is greater than or equal to 0.8 mm and less than or equal to 1.5 mm, the thickness ratio between the two strips is less than or equal to 1.3; If the thickness of the two steel strips is greater than or equal to 1.5 mm, the difference in thickness between the two steel strips is less than or equal to 0.4 mm.

5. The narrow lap welding method of 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel according to claim 1, characterized in that: The pre-welding treatment includes cleaning the welding position by a mechanical cleaning method.

6. The narrow lap welding method of 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel according to claim 5, characterized in that: The mechanical cleaning method includes rubbing and brushing the weldment surface using a grinding wheel or a wire brush or other tool.

7. The narrow lap welding method of 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel according to claim 1, characterized in that: The mass percentages of the main chemical components of the dual-phase steel are: C: 0.07-0.11%, Si: 0.33-0.48%, Mn: 1.65-1.75%, Si: <1%, and the rest are Fe and unavoidable impurity elements.

8. The narrow lap welding method of 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel according to claim 7, characterized in that: The mass percentages of the main chemical components of the dual-phase steel are: C: 0.09%, Si: 0.40%, Mn: 1.70%, Si: <0.6%, and the rest are Fe and unavoidable impurity elements.

9. The narrow lap welding method of 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel according to claim 7, characterized in that: The mass percentage of the main chemical components of IF steel is: C: 0.003~0.005%, N: 0.002~0.003%, Ti or Nb about 0.04~0.05%, and the rest are Fe and unavoidable impurity elements.

10. The narrow lap welding method of 590MPa grade cold-rolled dual-phase steel and 280-320MPa strength IF steel according to claim 9, characterized in that: The mass percentage of the main chemical components of IF steel is: C: 0.004%, N: <0.0025%, Ti or Nb about 0.045%, and the rest are Fe and unavoidable impurity elements.

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