Successive Spray Forming and Selective Heat Treatment of Composite Tool Steels

Abstract

Abstract In many metal forming applications, especially in micro cold forming, the tools are loaded differently in various functional regions. Tailored material properties in the specific regions are therefore advantageous. To meet this requirement, different tool steels can be applied in the corresponding regions of the tools, with a good bonding in between. This kind of composite materials can be produced by means of a newly developed successive spray forming process. In addition, the different steels in the composite tools may require quite different heat treatment conditions in order to achieve the expected material properties and performance. For this purpose, a selective heat treatment based on middle frequency induction heating has been developed to austenitize the different steels at different temperatures. In this study, these two newly developed processes have been applied to produce composite tool steels for micro cold forming tools. The investigation is focused on the correlation between the processing conditions and the microstructure and properties of the composite tool steels. It shows that fine and homogeneous microstructure can be achieved in the composite tool steels, with a gradual transition of chemical and physical properties in between. The microstructure and properties of the composite tool steels are clearly correlated with their austenitization conditions during the selective induction heating.