دانلود رایگان مقاله انگلیسی تکامل بافت و تغییر شکل پلاستیک آنیسوتروپیک منیزیم خالص در مسیرهای کشش - نشریه هینداوی

Abstract

The deformation behavior and texture evolution of pure magnesium were investigated during plane strain compression, simple compression, and uniaxial tension at room temperature. The distinctive stages in the measured anisotropic stress-strain responses and numerically computed strain-hardening rates were correlated with texture and deformation mechanisms. More specifically, in plane strain compression and simple compression, the onset of tensile twins and the accompanying texture-hardening effect were associated with the initial high strain-hardening rates observed in specimens loaded in directions perpendicular to the crystallographic c-axis in most of the grains. The subsequent drop in strain-hardening rates in these samples was correlated with the exhaustion of tensile twins and the activation of pyramidal <c+a> slip systems. The falling strain-hardening rates were observed in simple compression and plane strain compression with loading directions parallel to the c-axis where the second pyramidal <c+a> slip systems were the only slip families that can accommodate deformation. For uniaxial tension with the basal plane parallel to the tensile axis, the prismatic <a> and second pyramidal <c+a> slips are the main deformation mechanisms. The predicted relative slip and twin activities from the crystal plasticity simulations clearly showed the effect of texture on the type of activated deformation mechanisms.

5. Conclusions

The anisotropic stress-strain responses of strongly textured pure magnesium were investigated at room temperature under three di5erent monotonic deformation paths: (1) plane strain compression; (2) simple compression; and (3) uniaxial tensile tests. .e samples in these mechanical tests were oriented such that the loading direction aligned either parallel or normal to the crystallographic c-axis in most of the grains. .e main conclusions of this study are summarized below based on our experimental observations and supported by the predicted relative slip and twin activities using crystal plasticity simulations:

(a) .e activation of {1012} tensile twins and the accompanying texture-hardening e5ect were associated with the initial increase in strain-hardening rate observed in samples subjected to plane strain compression or simple compression with the loading direction normal to the crystallographic c-axis.

(b) .e transition in the stress-strain response from the initial increase in strain-hardening rates to the falling hardening rates was correlated with the exhaustion of deformation twins and the activation of slips along the second pyramidal <c+a> systems.

(c) .e slip on the second hard pyramidal <c+a> system was found to be the dominant deformation mechanism that can accommodate the plastic strains in samples subjected to plane strain compression or simple compression with the loading direction parallel to the crystallographic c-axis.

(d) .e prismatic <a> and second pyramidal <c+a> slips are the main deformation mechanisms during uniaxial tension when the basal plane is parallel to the tensile axis.