時計ゼンマイ材料の研究 (II)

概要

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Refering to the watch-spring, it may be classified in two, according to its size, for watches and for clocks. In general the former containing about 0.95∿1.2 per cent carbon has the mixed structure of the sorbite and the spheroidal cementite, and the other containing about 0.70∿0.85 per cent carbon has the sorbite structure having a few spheroidal cementite. On this second report the authors made research on what effect the size of the spheroidal cementite will give to the mechanical properties of the watch-spring. The results were as follows : (1) At the B heat-treatment, when the cementite size was below 2.8μ the fatigue breaking number, the torque test value, the proportional limit and the Young's modulus were at the maximum value while the permanent strain and the damping capacity were at the minimum value. (2) At the D heat-treatment, namely-below about 4.1μ of the cementite size the mechanical properties became worse abruptly and above this size they became the worst. (3) At the A heat-treatment, namely the spheroidal cementite being absorbed in the austenite, the mechanical properties were inferior to the B heat-treatment. (Refer to Fig. 1 according to the means of the marks A, B, C, D, E, F, heat-treatment.)
社団法人日本鉄鋼協会の論文
1952-06-25