Abstract
A newly developed testing system available to control temperature and the rate as well as applied stress or strain with high quality of extensometer is used to measure the transformation plastic strain occurring in the course of diffusion type transformation (including pearlite reaction). Specimens of six kinds of steels widely used for quenching operation are heated to austenite temperature of 900°C and kept at the steady temperature followed by cooling to lower temperature below transformation finish point subjected to several applied loads. Since the difference in the strain between zero and nonzero stress corresponds to the transformation plastic strain, the value of transformation plasticity coefficient is identified by the ratio of the strain to applied stress. Dependence of the coefficient on the chemical composition is discussed by defining an equivalent carbon content and compared with the data for plastic hardening coefficient.
