A resistance spot welding method suitable for three-layer plate with aluminum-silicon-coated hot-formed steel as the middle layer

Abstract

A resistance spot welding method suitable for three-layer plates whose middle layer is aluminum-silicon-coated hot-formed steel: Applicable welding material: middle-layer aluminum-silicon-coated hot-formed steel, and one side of the middle layer has a tensile strength not less than 500MPa cold-rolled sheet, the other side of the middle layer is a galvanized sheet with a tensile strength not higher than 450MPa; select electrodes; spot welding pre-compression on both sides at the same time; welding; holding pressure. The present invention increases the current density on the side of the galvanized sheet by using electrodes with different end face diameters on both sides, the current window can reach at least 9.6-11.2kA, and the window size is 1.6kA, which solves the problem of the aluminum-silicon-coated hot-formed steel on both sides When spot-welding the three-layer board with high-strength steel and galvanized board, due to the different strength, thickness and coating conditions of the steel board, the current density distribution on the upper and lower sides is uneven, and the phenomenon of virtual welding and spatter is prone to occur, making the resistance point The qualified rate of welding has increased from less than 50% to more than 90%, which fully meets the requirements of automobile manufacturers.

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