Effect of magnetic field on weld zone by spot-welding in stainless steel

Abstract

Spot welding is performed through a resistance welding process in which the components to be welded are clamped between two electrodes supplying heat current. It is known that a weld fusion zone and a heat-affected zone (HAZ), which experience high temperature followed by rapid cooling to room temperature, exhibit very different microstructures, compared with those of base materials. The microstructure of the weld fusion zone and HAZ (weld zone) is influenced by many factors such as chemical composition, welding condition and peak temperature. In this study, the effect of magnetic field on HAZ in spot welded stainless steel was studied. For this purpose, deformed and undeformed 301 type stainless steel (Fe-17mass%Cr-7mass%Ni-0.1mass%C-0.5mass%Si-0.99mass%Mn) samples with α′ martensite phase and γ austenite phase, respectively, were spot-welded under a magnetic field up to 2T. The welded surfaces and the cross-section planes were examined using an optical microscope. It was found that the area of HAZ was increased with increasing magnetic field, as well as the heat input power. Moreover, the area of weld zone in deformed stainless steel is larger than that in undeformed stainless steel. Based on the experimental results, the effect of magnetic field on HAZ in spot-welded stainless steel was discussed. © 2006 ISIJ.