Comparison of reduction ability between multi-stage cold drawing and rolling of stainless steel wire - Experimental and numerical investigations of damage

The present paper deals with the comparison between two multi-stage cold forming processes on an austenitic stainless steel, wire drawing and wire rolling, in terms of reduction ability. In the first step, experimental tests are carried out and reveal that, starting from an identical initial wire, higher reduction can be obtained with the drawing process. In the second step, numerical simulations are employed to investigate ductile damage in these two processes, using the phenomenological fracture criterion proposed recently by Bai and Wierzbicki (2008) and the coupled Lemaitre model in the framework of continuum damage mechanics (CDM). For the applications to forming processes, the models' parameters are identified first based on different mechanical tests at different loading configurations. Applications to wire drawing and rolling processes show the validity of these two models in fracture prediction both quantitatively and qualitatively. These two damage models are capable of predicting accurately the instant of fracture and also confirm the experimental comparative results between the reduction abilities of the two processes. Between the two studied forming processes, the results suggest the use of the drawing process instead of the rolling process to reduce wire section with minimum damage. It also shows that numerical simulations with the two developed damage models could be an effective tool to investigate ductile damage in other forming configurations or processes.