Effect Of Texture On Tensile Behaviors And Microstructure Of Extruded AZ31 Magnesium Plate

Due to the hexagonal close packed（HCP）structure of magnesium and its alloy,the wrought alloys by rolling or extruding have strong anisotropy and the texture will be formed.The existence of texture has an important effect on the mechanism properties.Mg-3Al-1Zn（AZ31）magnesium alloy is one of the most widely used wrought magnesium alloys.During the deformation,it will form the strong basal texture which is a good system for studying the reasons of strong anisotropy about the tension.Optical microscopy,electron back-scattered diffraction and transmission electron microscopy were used to help to analyze microstructure evolution of magnesium plate and corresponding deformation mechanisms during tension.The grain size and yield strength at each angle,θ,between the tensile loading direction（LD）and normal direction（ND）of the plate,obeys Hall-Petch relationship σ_y=34.53+2.87D^-1/2（0o）,σ_y=18.48+4.94D^-1/2（22.5o）,σ_y=4.69+6.89D^-1/2（45o）,σ_y=10.81+6.51D^-1/2（67.5o）,σ_y=27.31+3.69D^-1/2（90o）.There is a greater difference of yield strength within differentθin larger grains.Besides,the Hall-Petch parameters,σ₀ and k_y,follow different rules at each direction.With the increasing ofθ,the friction stress,σ_0,first decreased then increased and stress concentration factor,k_y,first increased then decreased.In 0o-45o and 45o-90o intervals,σ₀ and k_y show a good linear correlation.The relationship between texture and deformation mode is that extension twinning is dominant when LD//[0001],basal slip is dominant when angle between LD and[0001]is 45o,dominated by prismatic slip when LD is perpendicular to[0001].When combine the effect of two main texture of extruded AZ31 plate to investigate the mechanical properties and deformation mechanisms.At 0o（tension along ND）and 90ocase（tensile along TD）dominated by extension twin and prismatic slip with higher σ₀.Atθ=22.5o,extension twinning dominated at this angle with the help of basal slip to coordinate deformation.At yielding of 45o,basal slip is the dominant deformation mechanism which leads to the lowest σ₀.At 67.5o,extension twin and basal<a>slip dominates at yielding.Texture has a great impact on deformation modes.The σ₀ when dominated by slip and extension twin is higher than just dominated by basal slip.