Model for predicting ductile fracture of SA508-3 steel undergoing hot forming

Abstract

On the basis of the tensile tests that were conducted on a Gleeble thermomechanical simulator at various temperatures and strain rates, the fracture behaviour of SA508-3 steel was investigated, and a model for predicting the occurrence of ductile fracture during hot deformation was established. In order to determine the critical fracture strain ϵ f that initiates the necking of the material, a ‘virtual’ part of the specimen was created according to the constant volume condition to replace the necking volume of the specimen. Experimental results indicated that ϵ f depends on temperature and strain rate, and subsequently, a model of ϵ f was established. In conjunction with Oyane's fracture criterion, an evaluation method for predicting the fracture of SA508-3 during hot forming was reproduced. The model was verified by upsetting tests, and good coincidence was obtained. As an application, it was applied to a simulation of a forging stretching process, and the calculated results showed the model has preferable predication performance.