Surface treatment evaluation of induction hardened and tempered 1045 steel

Rod-shaped samples of SAE-AISI grade 1045 steel with a ferrite and pearlite structure in the as received condition were subjected to induction hardening to increase the hardness of the surface layer. The heat treatment process was carried out using induction heating with five different peak temperatures: 8000C, 9000C, 10000C, 11000C and 1200 0C for 2 s, before water quenching. The chemical composition and the microstructures of these samples were characterized by spectrometry and optical microscopy. The microhardness of the surface of each samples was measured and preliminary tensile testing was conducted. The results showed the formation of a significant hardened case due to the formation of martensite, while the core retained its original ferrite-carbide microstructure and was softer and tougher. Tempering was carried out 3000C, 5000C and 7000C in order to stress relieve the quenched samples and to increase the toughness of the steel case with an acceptable reduction in hardness.