高硬度鋼の強度, 靱性評価

抄録

The strength and toughness of a low alloy steel (0.8% carbon), quenched from 850°C and tempered at various temperatures below 600°C, have been investigated by static and dynamic bend tests and static torsion tests. The effect of notch radius on bend properties has also been studied. The results obtained in this study are summarized as follows:(1) The plastic deflection in the static bend test or the impact value decreases exponentially with increasing the stress-concentration factor “α” at the notch root.(2) The appearance of low temperature temper brittleness is markedly affected by test methods, that is, it appears at relatively low tempering temperatures and the embrittlement is more clearly observed in unnotched dynamic bend or static torsion tests than in static notched and unnotched bend tests.(3) An optimum hardness is observed on the fracture strength versus hardness curve in both bend and torsion tests.