The Microstructure of AZ 31 Magnesium Alloy by Forward Extrusion with Various Extrusion Parameters

Abstract

Samples of AZ31 wrought magnesium alloy are hot extruded into forward direction with various initial billet temperatures and extrusion ratios (ERs). Usually the insufficient room temperature formability of magnesium wrought alloys makes processing steps like rolling, extrusion etc. difficult, thus limiting their use for rolled or wrought parts. However, in this paper experiment is preformed under the hot forward extrusion process for AZ31 wrought magnesium alloy with different important parameters. Major process parameters such as punch speed, billet temperatures and ERs are considered and applied to the hot extrusion process with a constant value of the die land. The influence of different billet temperatures and ERs on the hot forward extrusion process is investigated and analyzed in terms of the grain flow, microstructure, grain size and hardness distribution of formed part for magnesium and Mg alloy. Maximum forming loads for various main parameters is tackled and checked to know the optimum forming load for hot forward extrusion process. Also finest grain sizes and an inhomogeneous microstructure of extruded parts seem to occur near the die land of tool-set due to the anisotropic plastic behavior during the hot extrusion process. Extrusion properties such as extrusion load, grain size, micro hardness and surface quality are compared between the main parameters during the hot forward extrusion process. In addition it is easily disclosed from the experiment results that the die land designed for safe tool-set plays a key role in improving the mechanical properties of formed product during hot forward extrusion process for AZ31 magnesium alloy.