IN-SITU EBSD INVESTIGATION OF CARBIDES DURING ANNEALING OF AISI M42 STEEL

摘要

In conventional high-speed steels, the eutectic carbides M_2C or M_6C are formed during solidification, with grain size and morphology dependent on alloy composition and the solidification conditions. Large carbides can be detrimental to property development during plastic deformation, and so thermal treatments that can beneficially modify carbide phases prior to forging are of interest. The aim of the present work was to characterize the decomposition of eutectic carbides during annealing of AISI M42 steel at the typical forging temperature of 1100℃. Specific large eutectic carbide grains were characterized before and after annealing for different times. Due to the systematic observation of carbides growth and their transformations based on in-situ EBSD investigation, models were proposed which help us to design future thermo-mechanical processes for tool steel production. In-situ EBSD observation is made at the surface of the material, so presence of free surface affects the diffusion processes and the result is not the same as in the bulk.