歯科用コバルト・クロム合金線のひずみ時効に関する研究 : 第 II 報ひずみ時効に及ぼす要因効果

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In the previous report the author presented the influence of diameter of Co-Cr alloy wires on their strain-aging properties. In many cases, the difference of diameter implies the difference of final reduction of wire, and so the latter may also be expected to have an influence on its strain-aging. Therefore, in this paper the author presented the influence of the final reduction on the strain-aging of some commercial clasp wires which had the same diameter. Tensile tests and microstructure observations were made to verify the differences of aging effect. The results obtained were as follows : 1. The final reduction of wire seemed to have not the same influence on all its properties after aging. The most influenced were especially the yield stress and the tensile strength. 2. Aging temperature, aging time, mutual action btween temperature and reduction and between temperature and time influenced on the yield stress after strain-aging evidently. 3. Mutual action between temperature and time and between reduction and time influenced, evidently, on the modulus of elasticity after strain-aging. 4. Above 600℃, the microstructures showed the precipitation of a new phase and the recrystallization in the grain boundaries. From these facts above mentioned it may be led as a conclusion that the most effective strain-aging of the wire studied could be attained by heating at about 500℃, for about 15 minutes.
1969-09-30