Weld surfacing of aluminium alloy by Ni—Cr base alloys

Abstract

This article describes the microstructure, microhardness, and the abrasive wear behaviour of the Ni—Cr base alloy overlays deposited on the Al—Zn—Mg alloy (7039) substrate by the shielded metal arc welding process. The weld overlays were deposited by using four levels of the welding current in the range from 110 to 140A. Abrasive wear tests were carried out by using a pin-on-disc wear tester under a spiral wear track. Wear tests were carried out using three normal loads (5N, 10N, and 15N) and abrasives of three grit sizes (120, 320, and 600 grade). Scanning electron microscopy, X-ray diffraction, and the energy dispersive analysis of X-rays studies were performed on the weld overlay to characterize the microstructure, composition, and phase analysis. It was found that from the microstructure point of view, three different zones are formed in the weld overlays. These zones exhibited significant variation in terms of the nickel and the aluminium content in the micro-constituents. The microhardness has been found to decrease from the top surface of the weld overlays to the base metal.