Multi-stage metal forming: Variation and transformation

During precision forming of metal parts made of metastable austenitic stainless steels, the relationship between the scatter on the initial parameters like the strip thickness, yield stress, etc. on the product accuracy need to be known. This becomes complex if the material is instable, i.e. martensite forms very easily. The transformation rate depends on the stress state, which is related to friction. It also depends on the temperature, which is related to deformation heat. A greater understanding of these phenomena is obtained by doing a process window study, using design and analysis of computer experiments (DACE). This paper demonstrates how to perform a DACE study on a three-stage metal forming process, using distributed computing. The study focuses on: •Hardening due to strain-induced and stress-assisted transformation. •The influence of metal forming parameters on the product accuracy.