Multilayer Mg–Stainless Steel Sheets, Twinning and Texture Evolution

Abstract

In the present study, different combinations of multilayer sheets were prepared from 1 and 2 mm Mg AZ31 along with 0.25, 0.5, and 1 mm 304 L stainless steel. The texture and microstructure of the elongated samples (20 and 30 pct strain) were studied. It was found that the transversal stress plays an important role in both texture evolution and twinning in these composites. The obtained pole figures revealed an axial texture tilt with increasing steel layer volume fraction (Vf). It was found that this is a direct effect of transverse stress, which becomes more significant upon reducing Mg Vf. This extra stress component tilts the basal planes away from the original normal direction in monolithic samples. Moreover, our results indicate that with decreasing Mg Vf, twinning activity was increased in the 20 pct deformed samples but reduced in the samples with 30 pct elongation. It is known that at high strains where sufficient transverse stress is generated, the activity of prismatic slip is significantly enhanced, which promotes the motion of dislocations and reduces the necessity of twinning. With decreasing Mg Vf, stronger transversal stress is generated and Mg reaches the critical threshold of prismatic activity at lower strains.