Abstract
The temperature dependences of the tensile properties and the Vickers hardness of some bcc metals, tungsten, molybdenum, mild steel (SS 41) and pressure-vessel steel (Coltuf-28), were obtained over a temperature range which contains the respective ductile-brittle tensile transition point. Neutron-irradiation effects on the correlation of the Vickers hardness with the flow stress were examined. Also the correlations of the Vickers hardness with the compressive yield stress of unirradiated materials were examined. It was found that the Vickers hardness is proportional to the tensile flow stress and the ultimate tensile stress only over a narrow temperature range. As the deformation process moves from the ductile temperature range to the brittle one, the correlation of hardness with flow stress deviates from a straight line and the junction points are produced. It became clear that there exists a tensile flow stress which makes the correlation of the Vickers hardness with flow stress constant before and after neutron irradiation. The relation between yield stress and the Vickers hardness before and after neutron irradiation is discussed using the modified Ludwig-Davidenkov model in cleavage fracture. Also the strain distribution under a Vickers impression on tungsten was determined using a split specimen.
Published Version
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