Special Case of Destruction of the End Mill Made of HighSpeed Steel Powder

Abstract

Comparing with cast steels high-speed steel powder S390 Böhler MICROCLEAN® has better properties, which is determined by the technology of its manufacture: this steel is high-alloyed, contains an increased amount of carbon and carbide-forming metals. In contrast to cast steels, its microstructure has no carbide inhomogeneity. Despite many advantages and long life of steel S390, explained by its balanced microstructure and chemical content, sometimes early tool failures occur. The article provides the grounds for tool failure connected with the peculiarities of heat treatment conduct. The authors establish the influence of a heat treatment mode on the number and content of carbide phases. The authors give recommendations for increasing the tool service life. This article gives the results of the steel macro- and microstructure research. In the course of research hardness was measured and the content of chemical elements was determined. The phase composition was defined with the help of the X-ray diffractometer Shimadzu XRD-6000. The amount of retained austenite was defined by means of the X-ray method of “four peaks” at the diffractometer Xstress 3000. The distribution of chemical elements was studied with the help of a microprobe X-ray analyzer Camebax SX50 while the surface topography was studied with the help of a scanning electronic microscope with the 100-3000-fold magnification.