高温焼入れした軟鋼の焼戻しにおける硬度と靱性におよぼす硫黄の影響
1969 年 55 巻 2 号 p. 145-150
詳細
1969 年 55 巻 2 号 p. 145-150
The changes in hardness and notch toughness with tempering of mild steels (10 mm∅), water-quenched fromhigh temperatures above 1200°C, were studied with particular reference to the effect of sulfur content.
The results obtained were as follows;
(1) On tempering at temperatures above 500°C, it was observed that the resistance to softening increaseswith increasing sulfur content. This effect of sulfur was found to be dependent on the solid-solution hardeningof ferrite, caused by the increase of solubility of sulfur.
(2) It was shown that the relation between quenching temperature and hardness tempered at a temperatureabove 600°C corresponds approximately with the relation between the temperature and solubility sulfurin austenite.
(3) Sulfur dissolved in the matrix acted to reduce the notch toughness in the mild steel containinghigher sulfur.
(4) Mild steels quenched from high temperature were superior in notch toughness to Ni-Cr steels containing similar amount of sulfur.
