Physical and numerical simulation of the production chain of fasteners manufactured of 32CrB4 steel control-cooled in the stelmor process to develop the multiphase microstructure

Abstract

The development of the concept of Thermomechanical Controlled Processing (TMCP) in the wire rod rolling mill of CMC Poland has opened up new opportunities for the production of fasteners without the application of heat treatment. The crucial effect of TMCP in the case of wire rod rolling is its capability of shaping fine austenite grain size following the last pass, typically below 20-25 μm in the wire rod cross-section. This is a prerequisite for obtaining the required cold workability level for the cold forming of fasteners, even if hard constituents (bainite, martensite) are present in the wire rod structure. In this paper, the physical simulation and numerical modelling capabilities were described for the design of cooling conditions in the Stelmor process and cold heading operation. The investigated material was conventional 32CrB4 grade used for the fasteners production with the application of heat treatment.