Micro-cracking of low carbon steel in hot-forming processes

The deformation characteristic of low carbon steel under hot compression conditions at the temperature range of 650-1000 °C was investigated using Gleeble 3800 thermo-mechanical simulator in the present study to better understand the formation of micro-cracking. Change of microstructures was also observed using an optical microscope. The hot deformation process was numerically simulated using finite element technique to determine the local strain, strain rate, and temperature distributions. According to the present work, the microstructure changed quite differently after the deformation at various temperature levels. The grain size and shape were also varied during the deformation process depending on the characteristics of metal flow. The initiation of micro-crack was found to be strain and temperature dependent. Such a micro-cracking was easy to initiate at the position with high stress and strain, especially at the grain sliding boundaries.