鉄の炭化物 : 焼戻におけるその挙動

概要

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The author reviews at first his previous works on jron carbides by electron-diffraction method. Conditions of formation and decomposition of carbides are described briefly. Under 300℃, carburizing gases (CO or CO+H_2) act as oxidizing agent but this difficulty is avoided by covering the specimens with fine powder of reduced iron. Thus the author obtains the hexagonal iron carbide (ε phase). Starting from this carbide, by heating in vacuo intermittently or continuously, the author observes the transition ε→χ→θ→Fe-C and he finds no precipitation of graphite when χ phase transforms into θ phase. Namely, it appears to him that the transition is an allotropic change. This indicates that the iron carbides have approximately the same composition or they have relatively wide range of composition. The author believes that the latter view is better for interstitial alloys like iron carbides. The author studies the tempering mechanism of quenched steel by measurement of instantaneous specific heat and he finds five principal peaks on the curve. A tentative mechanism of tempering is proposed. (1956.4.26)
社団法人日本鉄鋼協会の論文
1956-08-01