水噴霧高速度工具鋼粉の凝固組織および加熱に伴う組織変化について

概要

論文の詳細を見る
The machinability, grindability and toughness of sintered high speed tool steels produced by water-atomization of melt are expected to be superior to conventional cast and wrought ones, because of finely and uniformly dispersed carbides.As the results of it, chipping resistance and grindability have been confirmed to be excellent in practical use.In this study, microstructure and its change at elevated temperature were investigated on various particle sizes of water-atomized powders of SKH 57.In as-atomized powders, there appeared networks of primary carbides, where the smaller the particle size, the finer the network and also the smaller the dendrite arm spacing. Carbides in as-atomized powders were further confirmed to consist of MC and M2C, the amount of which decreased with a decrease of particle size. After heating at temperature higher than 1100°C, net work carbides in larger particle were proved to coarsen, while carbides in fine particles of about 40μ were inclined to spheroidize with network carbides disappearing. When heated at temperature higher than 700°C, M2C carbides were also proved to decompose into MC and M6C.As mentioned above, the carbide morphologies of heated powders were essentially influenced by the particle size of as-atomized powders, and to conclude, fine powders result in fine size and uniform distribution of carbides in both as-atomized and heated conditions
大同特殊鋼株式会社の論文