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, one side of the middle layer has a tensile strength not less than 500MPa cold-rolled plate, the other side of the middle layer is a galvanized plate with a tensile strength not higher than 450MPa; electrodes are selected; spot welding preloading is performed on both sides at the same time; welding; pressure maintaining. By using electrodes with different end diameters on both sides, the present invention increases the current density on the galvanized plate side. The current window can reach at least 9.6~11.2kA and the window size is 1.6kA, which solves the problem on both sides of the aluminum-silicon coated hot-formed steel. When spot welding a three-layer plate of high-strength steel and galvanized plate respectively, due to the different strength, thickness and coating conditions of the steel plate, the current density on the upper and lower sides is unevenly distributed, and it is easy to cause false welding and spattering, causing the resistance point to The welding pass rate has increased from less than 50% to more than 90%, which fully meets the production and manufacturing 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