Elevated Temperature Deformation Characteristics of 15Mn7 Steels

Abstract

Isothermal compression deformation tests of medium-Mn (0.15C-7Mn in wt%) steels (15Mn7) at elevated temperatures were carried out on a Gleeble-3500 thermal mechanical simulator. Hot deformation behavior of the steels was examined with a constant strain rates of 0.001, 0.01, 0.1 or 1 1/s between 1150 ºC and 900 ºC. The effects of deformation strain rate (0.001~1 1/s) and temperature on compression behavior of the steels was studied. It shows that the deformation conditions have significant influence on stress-strain curves of the steel. The curve shows obvious dynamic recrystallization style at high temperature, and low strain rate or dynamic recovery or work-hardening style at low temperature and high strain rate. The deformation resistance decreases with deformation temperature increasing and strain rate decreasing, and the peak stress and peak strain both decrease, which demonstrates that dynamic recrystallization is more easily to occur at high deformation temperature and low strain rate. The austenite hot deformation equation was established as following. And the corresponding hot deformation activation energy Qdef for the steel is 320.984 KJ/mol.Z0.15c−7Mn = ε˙exp(320984/RT) = A[sinh(ασ)]n = 1.15 × 1010[sinh(0.0156σp)]4.01