Effect of Welding Thermal Cycle on Mechanical Properties and Corrosion Resistance of A7N01-T5 Aluminum Alloy

Abstract

In this paper, the thermal cycle treatment of A7N01-T5 aluminum alloy was carried out with the peak temperatures of 480, 420, 320 and 260 °C, and the thermal simulation specimens with four kinds of peak temperatures were obtained. Electrochemical methods such as open circuit potential, polarization curve and impedance were used to investigate the corrosion behavior about the four kinds of thermal simulated specimens. The results showed that the mechanical properties and corrosion properties of the specimens after thermal cycle changed significantly, and the specimens which experienced high temperature (480, 420 °C) thermal cycle was more significant than that experienced low temperature (320, 260 °C) thermal cycle. The mechanical properties results showed that the tensile strength of the specimens under high temperature thermal cycle was higher than that of base metal, while the strength of the low temperature cycle was lower than that of base metal, and the specimens were softened after low temperature thermal cycle. Electrochemical experimental results showed that the corrosion resistance of the specimens under high temperature thermal cycle was weaker than the low temperature thermal simulation. However, the corrosion resistance about four kinds of thermal simulation parts was worse than that of the parent material base metal. The grain size and the distribution of precipitation phase changed by the rapid of heating and cooling process in welding heat cycle, thereby affecting the mechanical properties and corrosion resistance performance of the thermal simulation parts, and the specimens that experienced different peak temperature would have been experienced different evolution process, so the distribution of grain boundary continuity was different. Thus, the welding thermal simulation parts with different thermal cycles also exhibit different corrosion resistance.