The Influence Of Pre-deformation On Microstructure And Age Hardening Of Mg Alloys

Cold working before aging is an important method to enhance precipitate hardening effect of metals.In this paper,the influence of different pre-deformation methods on the texture and mechanical properties of two types of Mg alloys: rolled Mg-14Gd-0.5Zr plate and hot rolled AZ80 plate was systematically studied.The microstructure,texture,age hardening response and mechanical properties during pre-deformation and aging were addressed.The results shows that:(1)For Mg-14Gd-0.5Zr alloy,the two-stage hardening and rolling accompanied by low temperature aging hardly affect the peak hardness,but vary the time to reach peak hardening.The second process can largely reduce the time to reach peak hardening.(2)For Mg-14Gd-0.5Zr alloy,a weak basal texture forms after hot rolling.Cold rolling develops a RD-tilt texture with two peaks of basal poles tilting about 15° away from the ND.Aging treatment does not change the texture.(3)For cold rolled Mg-14Gd-0.5Zr alloy,precipitate prefers to appear at the grain boundary and twin boundary,forming a band distribution.Lamellar structure is observed in some grains,which has not been reported previously.(4)For AZ80 alloy,two types of pre-deformation,tension and rolling,was subjected to this alloy.After aging treatment,pre-treatment does not obviously enhance the yield strength and reduce the elongation.The treatment,3% rolling + 5% tension has the highest yield strength.(5)For AZ80 alloy,pre-tension generally generates dislocation structure,but rolling forms both dislocation and twins.The twins benefit precipitation within them.The precipitates has a low aspect ratio in pre-tensioned sample,but higher one in the pre-rolled one.