Auger electron spectroscopy studies of impurity effects on the hot deformability of AISI M2 high speed steel

The effects of various materials parameters on hot deformability f of AISI M2 high speed steel are studied in a complex way. These studies revealed beside other parameters (e.g. carbides) a strong correlation between some impurities (S, Sn) and f, determined by hot deformability tests. The correlation between f and the P content prooved to be weaker. The paper is devoted to impurity effects. The composition and impurities of the samples and their isolated carbide phases have been determined by chemical analysis. In situ AES fractography and SEM were applied to study the fracture surfaces. The main results are: The S concentration of the fracture surfaces exhibits a correlation with the bulk content. Strong enrichment of S and P within a thin (1–3 nm) surface layer was revealed by AES in-depth profiling, showing also carbide phases. In the temperature range -150°C — +250°C no grain boundary fracture was observed, fracture was ductile and void type. The fracture path is determined by carbides, being the sites of S and P enrichment.