Effects of temperature on the cyclic deformation behaviour and microstructural changes of 12Cr-1MoVW martensitic stainless steel

Abstract

Strain-controlled uniaxial push-pull fatigue tests were carried out with cylindrical specimens of 12Cr-1MoVW steel from room temperature up to 600°C. Specimens were tested at a total strain range of 2% at room temperature, 300°C, 400°C, 500°C and 600°C, respectively, and were also tested at 500°C for a total strain range of 1·6%, 1% and 0·6%. The fatigue test results showed that the cyclic deformation behaviour of this steel was strongly dependent on the test temperatures. TEM studies revealed that cellular dislocation structure comprised the major microstructure and the subgrain size increased with increasing test temperatures. Carbides tended to redistribute along the subgrain boundaries in the specimens subjected to low cycle fatigue at high temperatures. The undeformed section of each specimen exhibited a completely different microstructure from that in the gauge section in all the temperatures tested. The lath martensite structures were not changed obviously when HT-9 steel cyclic deformed at lower strain range.