Papers by Keyword: Electro-Plastic Effect

Abstract: In this paper, pure metals Ti and Ta were used to study the effects of impulse current on their mechanical properties. The results showed that the impulse current caused the tensile strength of the two metals to decline remarkably. The elongation of metal Ta rose and was enhanced with increasing current density. But as for metal Ti, the elongation hardly rose. Theoretical analysis suggested that the impulse current had little apparent effect on HCP metals, for it had less slip systems; however, it had obvious effects on the elongation of BCC metals, for they had more potential slip systems. The transmission electron microscopy (TEM) observations showed that crystal microstructure of the two metals had not changed significantly.

Abstract: A modified linear-elastic fracture mechanics approach proposed by McEvily has been applied to predict the effects of small defects on the fatigue limit and the threshold level. In the analysis, three modifications were taken into account (1) the effect of elastic-plastic behavior of small cracks, (2) the Kitagawa effect where in the very small crack regime the required stress for propagation is controlled by the fatigue limit of a smooth specimen rather than by the long-crack threshold condition, and (3) the effect of crack closure development from zero up to the macroscopic level as a newly formed crack extends. Three steels, a brass and an Al alloy were investigated. Good agreement between predicted and experimental results has been obtained and a rational basis for the area parameter model was shown.