The Rate (Time) -Dependent Mechanical Behavior of Modified 9Cr- 1Mo Steel - I. Experiments at 538°C

An experimental technique for measuring internal back stress was proposed by Mitra and McLean in 1966. Later stress and strain transient dip tests were introduced. Recently dip tests have attracted the interest of researchers in the area of constitutive equations. The purpose of this effort is to investigate the internal stress behavior for modified 9Cr-1Mo steel at 538°C. Test results may be used to further improve unified viscoplastic models of the overstress type, where thorough understanding of the back stress behavior is important. The present paper also reports on uniaxial monotonic tests at strain rates ranging from 5.0x10^-3 to 1.0x10^-7 s^-1 with relaxation tests which were performed to determine short term mechanical behavior and influence of the recovery of state.