DEPENDENCE OF COMPRESSION-TENSION LOADING ON TWINNING IN WROUGHT Mg ALLOY

摘要

Wrought magnesium alloy AZ31 was pre-compressed and subsequently subjected to tensile loading. Due to a strong fibre texture of the alloy the level of pre-compression stress significantly influences the following tensile test. The results of acoustic emission (AE) measurement are correlated with the stress-time curves and differences in the AE count rate were used to reveal changes in underlying deformation mechanisms. First, the compression-tension test was recorded by using the AE technique and then the test was repeated to specific points on the deformation curve, where the AE count rate exhibits strong changes in its activity. A pronounced S-shape of the tensile curve and AE peaks were observed. It highlights the role of detwinning and the nucleation of new twins during the tensile test. The subsequent analysis of microstructure using electron back scattered diffraction (EBSD) method opens a detailed insight into microstructural changes.