Instability map based on specific plastic work criterion for hot deformation

Abstract

Estimating workability is very important to complete the hot or cold working process successfully without making any crack. Instability map was developed by utilizing conventional plastic work criterion in the current study. Hot compression tests were conducted using Gleeble 3800 simulator to obtain flow stress curves as a function of temperature and strain rate. Based on the compression results, new instability map based on the specific plastic work was developed for estimating the instability during the hot deformation process. The critical specific plastic work value was determined by investigating the surface irregularity and shear band formation in the compressed specimens. Then, the instability map determined was applied for predicting surface wrinkle defect during the multi-pass hot bar rolling in combination with the finite element analysis. The predicted results using new instability map suggested matched well with the observations obtained from the industry. The developed approach is easy to apply to the available simulation tools to determine necessary processing parameters.