Microstructure/Mechanical Property Correlations in a Medium Carbon Steel

Abstract

The tensile and fracture strength of a medium carbon steel containing 0.2wt%C were determined after austenitisation at 1100oC for 1 h and subsequent isothermal transformation at 700oC for 0.5, 2, 6 and 8 h. Only the specimens transformed for 0.5 and 2 h contained martensite and these were l5.67 and 7.20%, respectively. The maximum measured tensile and fracture strength were 91l and 852 MPa, respectively and these were obtained in the specimens with the most martensite (0.5 h). Although after austenitisation and subsequent isothermal transformation there was a loss in ductility, this was accompanied by a very significant improvement in tensile and fracture strength.