A Study Spot Welding of Plated Steel (Part 1)

Welding conditions and mechanical properties

Abstract

This paper is concerned with the weldability of spot welding nickel, copper, chromium and tin plated steel in 1 mm thickness. The apropriate welding condition range, mechanical properties, hardness of the weld nugget, nugget shape and the voltage drop across electrodes are studied and the optimum welding conditions are determined for each plated steel.
As the result of investigation, the following are concluded.
(1) Welding condition is greatly dependent of the kind of metal plated on steel. Higher welding current is required for the tin and the copper plated steel and lower current for the chromium plated steel comparing with the bare steel. High electrode force is recommended for spot welding of the chromium plated steel. The time necessary to produce a nugget is longer in the case of plated steels than of the bare steel and consequently longer weld time is recommended for spot welding plated steels.
(2) When electrodes with the same shape and dimensions are used, tensile shear strengths of plated steels are nearly equal to that of the bare steel, but cross tension strengths of the nickel and the chromium plated steel are considerably low.
(3) The welding conditions depend a little on the plating thickness over the range from 2.5 to 10 p in thickness.
(4) The nuggests of the nickel, copper and chromium plated steels are high in hardness and the hardness of the weld nugget of the tin plated steels is about the same as that of the bare steel.