引張試験中の低炭素鋼の非線形音響特性の変化

抄録

In this study, we investigated the evolution of two nonlinear acoustic characterization; resonant frequency shift and three-wave mixing, with electromagnetic acoustic resonance (EMAR) during tensile test of a low carbon steel, JIS-S25C. EMAR was a combination of the resonant acoustic technique with a non-contact electromagnetic acoustic transducer (EMAT). We used bulk shear-wave EMAT. Tensile tests of plate specimens were interrupted at several strain conditions; before upper yield stress, at upper yield stress, at lower yield stress, after lower yield stress and at tensile strength. Two nonlinear acoustic parameters increased with increase in strain. Before tensile strength, they showed peaks. They trends were similar to dislocation density measured by X-ray. We interpreted these phenomena in terms of dislocation multiplication and formation of cell wall, with support from the X-ray observation.