鋼に於ける炭化物の球状化に就て (II) : 燒入鋼繰返加熱に依るセメンタイトの球状化に及ぼす炭素含有量の影響に就て

概要

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Quenched Sweden carbon steels containing about 0.1, 0.3, 0.5, 0.7, 0.9, 1.2 and 1.3%C were subjected to repeated heating and cooling passing A_1 point, and the effect of carbon content on the spheroidizing of cementite in those steels was studied. One cycle of heating and cooling was carried out as follows : 700°→760°, heating 1°/min., hold at 760° for 14 min. 760°→700°, cooling 1°/min., hold at 700° for 30 min. This cycle was repeated 1 to 5 times, and after each cycle the rate of spheroidizing of cementite was measured by means of Rockwell hardness tester. After 3 times of the cycle in Hypo-eutectoid steel and after 5 times of it in Hyper-eutectoid steel the spheroidizing was completed-that is, the lowest constant hardness was obtained. Difference of the quenched structure-if the same steel-does no effect on the final spheroidal structure and its hardness by this heat treatment. The final hardness of spheroidized steel thus obtained is expressed by following formula : Rockwell hardness in B scale=21×C%+72.9 This hardness is more or less higher than that of the spheroidized one made from the same steel having the lamellar pearlite structure.
社団法人日本鉄鋼協会の論文
1951-02-25