فهرست مطالب rouholah ashiri

LM13 alloy is widely used for piston production due to its low thermal expansion coefficient, high fluidity and good hot tear resistance. Optimization of production process and heat treatment are two effective factors in improvement of produced piston properties. In this research effect of change of casting process from gravity casting to squeeze casting on wear behavior of LM13 alloy was investigated. First the samples were cast using the two casting processes and heat treated. Then wear behavior of the alloy in two states of squeeze and gravity casting under dry sliding condition was examined and compared.Results of hardness and strength tests indicate that squeeze cast specimens have higher mechanical properties. The wear experiment results show that in both squeeze and gravity cast specimens, the amount of weight loss increases as the sliding distance increase, but the wear rate and the friction coefficient reduces. Comparing the properties of the two samples indicate that squeeze sample has better tribological behavior. Change of production process causes a decrease in friction coefficient from 0.4 to 0.2 for squeeze cast samples and also decreases the weight loss of the samples. Furthermore squeeze cast samples have better surface quality. In squeeze cast samples, abrasive, adhesive and delamination and in gravity cast samples, abrasive, adhesive and surface fatigue were recognized as the dominant wear mechanisms.