M. Mehdinia - Department of Steel Making, Iran National Steel Industrial Group (INSIG), Ahwaz. Iran
S. A. Jenabali Jahromi - Department of Materials Science and Engineering, Shiraz University, Shiraz, Iran

This experimental study investigated the effects of quenching and tempering heat treatment on fatigue behavior and also tempering temperature and time holding of AISI ۱۰۶۰ steel. At first, the specimens were austenitized at ۸۰۰˚C for ۱ hour, and then were quenched in the water bath of ۲۵˚C temperature. After that, tempering process was done at the temperature of ۲۵۰˚C, ۴۵۰˚C and ۶۵۰˚C for ۱ and ۲ hours. The results of mechanical properties indicated that hardness, tensile strength and fatigue limit was decreased with increasing the holding time and tempering temperature. Scanning electron microscope (SEM) results showed that crack propagation in the tempered specimens at the ۲۵۰˚C temperature in the ۱ hour was slower than in the specimens in the higher temperature and higher period time. As well, with increasing of the tempering temperature, germination areas of fatigue crack was increased and crack propagation was done faster.

AISI ۱۰۶۰ Steel, Tempering, Hardness, Tensile, fatigue