Resistance Spot Weld Ability of Mild Steel Coated with Zn, Galfan and ZA12

Abstract

In this study, the weldability of mild steel coated with different Zn-based materials to prevent corrosion with resistance spot welding process was investigated. For this purpose, the surfaces of mid steel were coated with pure Zn, Galfan (Zn5Al) and ZA12 (Zn11Al1Cu) alloys. Hot dipping technique was used for coating. Mild steels with dimension of 1.5X15X40 mm were immersed in the melted Zn and alloys, and the surfaces were coated by waiting for 2 minutes. Steel and coated steel pairs were joined by resistance spot welding process. The welding interface microstructures were examined under light optical microscopy (LOM). Weld interface strengths were measured by axial shear tests. The tests were performed at the room temperature and with a tensile speed of 5mmmin-1. Microstructure investigations showed a good bonding occurred between the coating and the steel and between the welded materials. Mechanical tests have shown that coating the steel reduces the weld strength and the decrease in strength continues with the increase of alloying elements in the coating.

Keywords

• Mild steel
• Coting
• Welding
• Strength

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