Effect of single-pass large-strain tube pack-rolling on forming AZ61 alloy strip

In this paper, a novel manufacturing strategy named as tube pack-rolling (TPR) was proposed. In the process, Mg-6Al-1Zn-0.3Mn (wt%) (AZ61) bar was packed by stainless-steel tube to be rolled at elevated temperature. In order to compare the advantage of TPR, AZ61 bar was also rolled without stainless-steel tube which is named naked-rolling (NR). The stainless-steel was picked as the pack material because of its high strength and hardness which can completely restrain the deformation of magnesium alloy. Numeral simulations were employed to analyze the strip shape and formability. The optimized parameters of contour control are discussed. Tensile tests at room temperature show that specimen rolled by TPR at 673 K exhibit good comprehensive mechanical properties, and the yield strength and ultimate tensile strength reached 213 MPa and 305 MPa with the elongation of 23.2%. The microstructure was investigated by optical microscopes (OM) and electron back scattered diffraction (EBSD). The AZ61 alloy strip rolled by TPR at 673 K exhibited homogenous almost fine dynamically recrystallized equiaxed grains (about 5 µm) with a weak texture. Meanwhile the microstructure evolution mechanism also shows the temperature has significant effect on TPR processing.