Effect of Heat Treatment on the Microstructure and Property of Aerospace Punch Dies

The purpose of this paper is to investigate the effect of heat treatment on the microstructure and property of punch dies used for precision stamping on aerospace mechanical parts. Many structural investigations were applied to identify the morphological characterization of high-speed steels with two technology variants: ordinary metallurgy (M2 and M42) and powder metallurgy (S390 PM). The results revealed that M2 HSS grades normally consist of primary carbides (peanut and skeleton-shaped M₆C (tungsten and molybdenum-rich carbides) and granular-shaped MC (vanadium-rich carbide)), while M42 and S390 PM structures contain bright and grey carbide phases. The bright homogenous phase is rich in W and Fe, while the non-homogeneous carbide is rich in V and W. The results also showed that the property of HSS punch dies as estimated by micro-hardness depends on many considerations such as heat treatment conditions, the size, distribution of carbide phases, carbon content, added elements (Co and Si), and manufacturing methods.