Positron annihilation in shock loaded low-alloyed MnSi steel

Abstract

The strengthening of metals and alloys by shock waves has been actively researched for the past three decades. It has been demonstrated that impulse loading, using explosive shock waves, strongly influences the strength of a variety of metals and alloys. As a result of shock loading an increase in hardness or tensile strength and a reduction in tensile ductility has been shown. These changes tend to be most significant at lower shock pressures. Shock loading at higher pressures ultimately leads to saturation'', i.e., a shock pressure is reached when there is little change in mechanical behavior with any additional increase in shock pressure. Microstructural examination had led various researchers to conclude that the observed changes in mechanical behavior after shock loading are due to an increase in dislocation density or to the introduction of twin and (or) martensite. The purpose of the present study is to investigate the influence of shock loading on the residual hardness of low-alloyed Mn-Si steel and to elucidate the defect structure by the positron lifetime technique.