Mo 系高速度工具鋼におよぼす Si 添加の影響

概要

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Rod-shaped primary carbides, M_2C, which were aligned with rolling direction are frequently observed in high-carbon, high-molybdenum high-speed tool steel. It was known that the phase disappeared by silicon addition to the steel. Therefore, the effect of silicon on the carbide transformation and the heat treatment characteristics in AISI M7 was studied under various nitrogen content. The results obtained are as follows : (1) The carbide precipitated at the eutectic reaction was M_2C and not M_6C, and had a plate-like morphology. (2) Silicon in the matrix accelerated the transformation of M_2C to M_6C by entering into M_2C during heating the ingot above 640∿700℃. Considerable primary carbides were retained as M_2C even after hot working, when the silicon content in the steel was little. (3) It was considered that the retained M_2C, having the plate-like morphology, became reorientated parallel to the hot working direction, without spheroidization, and therefore was microscopically observed as rod-shaped carbide.
社団法人日本鉄鋼協会の論文
1977-05-01