Features of basic and technological properties of powder high-speed steels

Abstract

In this work, the study of basic and technological properties of high-vanadium high-speed steels of M5F6-MP and M6F7-MP types, manufactured by the powder metallurgy method, is carried out. The samples of these steels were investigated and controlled for hardness as delivered, after quenching and tempering, for impact toughness and bending strength. The technological properties were controlled for workability by pressure, cutting and grindability. The effect of compaction schemes and modes on the microstructure and phase composition of steels was studied. The heat treatment mode was selected. It was established that the structure of powder high-speed steels was characterized by a uniform distribution of carbides of MeC and Me6C types both in the transverse and longitudinal directions with a size of no more than 1 µm. After hot compaction, the austenite grain remained fine, its diameter did not exceed 3 µm, and no graininess or porosity was found. No technological drawbacks were revealed during heat treatment of powder high-speed steels. Grindability of the studied powder high-speed steels, despite the high content of vanadium and carbon, is not inferior in grindability to traditional steels of satisfactory grindability P18 and P6M5. The use of powder technology opens up the prospect of introducing high-carbon high-vanadium high-speed steels into the industry, due to a significant improvement in the basic and technological properties, especially grinding. They can be recommended for the manufacture of tools with a complex profile.