Optimized Tension for AZ31B Thin Sheets Rolled with On-Line Heating Rolling

On-line heating rolling mill which could efficiently preheat sheet and apply tensile force on both ends of the sheet along rolling direction (RD) was used to investigate the effect of tension on mechanical behavior and shape quality of magnesium sheets. For revealing the influence mechanism, many analysis techniques including optical microscope, electron backscattered diffraction, macrotexture and transmission electron microscope were performed. The shape defect, edge wave, could be eliminated under higher tension along RD, which was attributed to more uniform distribution of microstructure and microstrain. Nevertheless, it is undesirable that the forward tensile force exceeds 3 kN in present work because the strength decreased for high recrystallization level when the tensile force is beyond this value. Furthermore, the main deformation mode was still slip during rolling process despite of accompanying twining, e.g., double twins, but more prismatic slip activated when tensile force exceeds 3 kN. The distribution of shear bands was affected by the applied tensile force that they appear as “V” shape along RD at a low forward or backward tensile force, while they appear as reticulate shape under applied tensile force of 5 kN.