Resistance spot welding method applicable to three-layer plate with middle layer made of aluminum silicon coating thermal formed steel

Abstract

The invention provides a resistance spot welding method applicable to a three-layer plate with a middle layer made of aluminum silicon coating thermal formed steel. The method is applicable to a welding material. The middle layer is made of the aluminum silicon coating thermal formed steel, a cold-rolled plate with the extension strength being no smaller than 500 MPa is arranged on one side of themiddle layer, and a galvanized plate with the extension strength being no higher than 450 MPa is arranged on the other side of the middle layer; electrodes are selected; spot welding and prepressingare carried out on the two sides at the same time; welding is carried out; and pressure is maintained. According to the method, the electrodes with the different end face diameters are used on the twosides, current density of the galvanized plate side is improved, the current window at least can reach 9.6-11.2 kA, the window size is 1.6 kA, the method solves the problems that when spot welding iscarried out on the three-layer plate with high-strength steel and the galvanized plate being matched on the two sides of the aluminum silicon coating thermal formed steel correspondingly, due to thedifferent strength, thickness and plating layer situations of the steel plate, the current density of the upper side and the lower side is not uniform, and insufficient welding and splashing occur easily, the yield of resistance spot welding is improved from the original percent smaller than 50% to the percent larger than 90%, and the requirement of production and manufacture of car factories is met completely.

Description

technical field [0001] The invention relates to a resistance spot welding method, which exactly belongs to the resistance spot welding method suitable for three-layer plates whose middle layer is aluminum-silicon coated hot-formed steel, and is more suitable for three-layer plates with different strengths, different thicknesses, and different steel types. Method for resistance spot welding of laminates. Background technique [0002] In response to the technical requirements of energy saving, emission reduction and body weight reduction, high-strength, light-weight alloys and other materials are used more and more in the body, and many parts of the body, such as front longitudinal beams, A-pillars, B-pillars, and C-pillars, have different strengths. , The matching of three-layer boards with different thicknesses, and the proportion of applications is increasing year by year. Since many structural components have three-layer boards or overlapping joints of multi-layer boards,...

AI Technical Summary

Problems solved by technology

[0006] The present invention overcomes the deficiencies in the prior art and provides a method to solve the problem of the steel plate being damaged when spot welding a three-layer plate of high-strength steel and galvanized plate on both sides of the aluminum-silicon coated hot-formed steel in the automobile manufacturing process. Different strength, different thickness, and different coating conditions lead to uneven distribution of current density on the upper and lower sides, prone to virtual welding, spatter, and insufficient three-layer board resistance spot welding method that cannot obtain qualified solder joints