Effect of Hot Deformation on Impact Toughness of High Strength Steel

Abstract

High Strength steel offers good combination of strength and toughness properties. These properties of high strength steel are strongly influenced by the hot deformation and controlled cooling parameters. The hot deformation behavior of low carbon high strength steel and its effects can be entailed and detailed by the analysis of microstructural and mechanical properties. In the present study, hot deformation was carried out in the temperature range of 1060°C to 1300°C followed by natural air cooling and forced air cooling. The microstructures were characterized by Optical Microscopy (OM) and Scanning Electron Microscopy (SEM).The mechanical behavior was investigated by hardness, tensile and Charpy V-notch impact tests. The test results indicate that, decrease in deformation temperature from 1300°C to 1060°C increases the impact strength from 13J to 31J. The microstructure evaluation shows that the toughness of the steel was enhanced by the formation of fine Bainitic sheaves and finer bainitic packets in lath-like bainitic structure at lower deformation temperature.