The Effects of Heat Treatment Temperature on Wear Characteristics of Hyper-Eutectic Al-Si Alloy Laser Clad Layer

Abstract

In this study, it was tried to analyze the effects of heat treatment temperature on the microstructure and wear characteristics of the hyper-eutectic Al-Si clad layer. The clad layer was produced by scanning pulsed Nd: YAG laser beam over the Si powder layer printed on the Al050 Al alloy base metal. The chemical composition of the clad layer was analyzed to be Al-20.8%Si. Despite the hyper-eutectic Al-Si composition, the clad layer mainly consisted of the very fine Al-Si eutectic microstructure without primary Si particles. The clad layers were heat-treated at 300 °C, 400 °C and 500 °C for 5 hours. The specimen heat-treated at 300 °C retained the very fine Al-Si eutectic microstructure, but the continuity of Si particles in the Si network was broken. In the specimen heat-treated at 400 °C, the Al-Si eutectic microstructure disappeared and fine Si particles were dispersed over the entire area. In the specimen heat-treated at 500 °C, the melt-solidification traces disappeared and Si particles were grown considerably. The wear weight loss was the lowest in the as-cladded specimen and increased with the increase of heat-treatment temperature. Adhesive wear did not occur in the specimens as-cladded and heat-treated at 300 °C, but occurred in the specimens heat- treated at 400 °C and 500 °C. The very fine Si networks in the Al-Si eutectic microstructure seemed to prevent adhesion of Al substrate to SKD 11 roll surface. Therefore, it was considered that there was no adhesive wear in the specimens which were as-cladded and heat-treated at 300 °C. Key words: Laser cladding, Hyper-eutectic Al-Si alloy, Heat treatment, Block-on-roll wear test, Friction coefficient, Adhesive and abrasive wear