microstructural development in AISI4140 and AISI1045 steels during tempering

It is the objective of this project to develop a fundamental understanding of the induction and furnace tempering process in terms of the effects of the tempering process parameters on the microstructure and mechanical properties of induction and furnace tempered parts. In this investigation 1 foot  ½ diameter rods of AISI 4140 were austenized at 850 for 1 hour and quenched in oil and 1 foot  ½ diameter rods AISI 1045 steels were austenized at 870 for 1 hour and quenched in water. These as-quenched steels were tempered in an atmosphere furnace and by induction at 250, 350, 450, 550 and 650 and for time from 1min to 15hours. The Rockwell hardness of each sample was measured. It was found that the Hollomon-Jaffe analysis successfully described the tempering behavior of the steel. In addition, the impact toughness and tensile properties were measured. In this paper these experimental results will be presented and discussed.