鉄鋼のぜい化のかたさによる研究

抄録

Hardness can be related to brittleness in steels through yield stress and reduction in area by the usual tensile test. Here the effects of low temperature, neutron irradiation and tensile work-hardening on brittleness in steels were investigated by Vickers hardness. The temperature dependence of Vickers hardness on several steels was studied over a range from -196°C to 100°C. It was found that the logarithmic hardness versus the reciprocal of absolute temperature can be described by several linear stages. If the intersection of the two lowest temperature stages is defined as a hardness ductile-brittle transition temperature, it will turn out that the increase in the transition temperature during the neutron irradiation is approximately consistent with the data obtained by the Charpy impact tests and reviewed by Pellini, et al.
The intersections of the two lowest temperature stages in the hardness-temperature curves of the tensile work-hardened steel shift to the higher temperature side as in the case of neutron irradiation, and it is considered that their increases are approximately in accord with the results obtained by the Charpy impact test.
Therefore it may be suggested that the influence of neutron irradiation on notch sensitivity may be neglected, and that low temperature, neutron irradiation and prestraining embrittlement in steels can be detected in terms of the temperature dependence of Vickers hardness.