抄録
High speed steel (hereafter, HSS) is a steel to which a large amount of alloying elements such as Cr, W, Mo, Co, and V are added. HSS suppresses the decrease in softening resistance of tool steels at high temperatures and enables cutting at higher speeds. The HSS are classified into molten HSS and sintered HSS. Sintered HSS has no lumps of carbide and no anisotropy. Due to the fine metal structure, sintered HSS has better mechanical properties such as strength and toughness than molten HSS. Therefore, this research aims to develop a high performance powdered HSS (composition of SKH 57) with excellent mechanical properties. SKH57 uses powder made by the water atomization method. In the water atomization method, very fine metal powder can be produced by injecting high pressure water into molten metal. The average particle size of the powder produced by this method is very fine, about 5 micrometers. After that, the metal powder was agglomerated into spherical particles of about 100 micrometers and pressed. After that, the sintering conditions were optimized. The microstructure observation, hardness test, bending test, and impact test of the test piece were investigated. As a result of the experiment, the hardness of the sintered HSS and that of the molten HSS are almost the same. However, sintered HSS has excellent mechanical properties such as bending strength, impact value and wear resistance.
