Tension deformation mechanism and fracture characteristics of high nitrogen steel 6Cr21Mn10MoVNbN at 25–800°C

Abstract

The tensile deformation behaviour and the fracture mechanism of 6Cr21Mn10MoVNbN alloy were studied in the range between 25–800°C using thermal simulator, hardness tester, optical microscopy, scanning electronic microscopy attached with energy dispersive spectroscopy and transmission electronic microscopy. Elongation of the steel was found to decrease as temperature increases, which was due to the growth of the coarse nitrides and carbides and the precipitation of Cr₂N at grain boundaries. It was also found that the fracture behaviour and deformation mechanism differed at different temperatures. At a low temperature, such as 225°C, the steel showed features of transgranular fracture and the deformation mechanism of the steel was dislocation slip and deformation twinning. At a high temperature, such as 800°C, the steel demonstrated characteristics of intergranular failure and the major deformation mechanism of the steel was dislocation slip and rotation of grains.