Mechanical properties and grain growth kinetics in AZ31 magnesium alloy after severe plastic deformation
Date of Issue2015
School of Mechanical and Aerospace Engineering
Severe plastic deformation (SPD) is defined as any metal forming process capable of imposing an extremely high strain on a bulk material and leading to an exceptional grain refinement and with no significant change in the overall dimensions of the sample [15-21]. SPD is mainly used for grain refinement of bulk metals to enhance the mechanical properties such as yield strength, ultimate tensile strength and etc. In this study, numerical simulation and experimental studies were conducted to examine the effect of SPD by Groove Pressing on AZ31 Mg alloy plate. The effect of heat treatment time and temperature on microstructure and hardness were subsequently examined on the as-processed Mg plate. The mechanism of grain growth was studied using the kinetic and Arrhenius equations. The microstructure evolution and tensile strength were examined on the as-processed specimens. After 3 cycles of Groove Pressing using the orthogonal deformation method and progressive reduction of deformation temperature, the average grain size of the Mg plate was reduced by 84.96% from 13.3μm to 2μm and the hardness was increased by 32.86% from 63 Hv to 83.7 Hv. This study has demonstrated that Groove Pressing is a highly effective method for production of fine-grained microstructures uniformly in magnesium plate. From the analysis of grain growth kinetics, the activation energy for grain growth was calculated to be 124.85 kJ/mol in temperature range of 200°C to 350°C.
Final Year Project (FYP)
Nanyang Technological University