挤压温度对AZT802镁合金组织和性能的影响

摘要

将铸态AZT802合金分别在350℃ 、380℃和400℃下挤压,随后进行T5时效处理,研究不同挤压温度对AZT802镁合金挤压态和时效态组织和性能的影响.结果表明,当挤压温度为350℃时,晶粒尺寸分布不均匀,同时观察到大块的条状第二相沿挤压方向析出.当挤压温度高于350℃时,挤压态合金获得均匀等轴晶粒,第二相以颗粒状形貌沿晶界均匀分布.经T 5时效处理后,颗粒状Mg2 Sn相均匀分布于基体中,Mg17 Al12相以连续相和非连续相析出,非连续析出相随时效前挤压温度的升高而逐渐增多.力学性能测试结果表明,AZT802合金在380℃下挤压,并进行175℃(3 h)T5时效处理后,获得最佳综合力学性能.%Extrusion of as-cast AZT802 alloy was performed in the temperature of 350 ℃ ,380 ℃ and 400 ℃ ,and then the extruded alloys were given T5 aging treatment .The effects of extrusion temperature on microstructure and mechanical properties of extruded and aged AZT802 alloy were investigated .It was found that fine equiaxed grains were obtained in alloys extruded at higher extrusion temperature .With the extrusion temperature decreasing to 350 ℃ ,the distribution of grain size was nonuniform .The volumes of the second phases decrease with the extrusion temperature increasing .Moreover ,the particle second phases distribute along the grain boundaries homogeneously at higher extrusion temperature .While large band-shaped precipitation was observed in the alloy extruded at 350 ℃ .After T5 aging treatment ,Mg2Sn particles distribute homogeneously .Both continuous and discontinuous Mg17Al12 phases were observed .The volume fraction of discontinuous Mg17 Al12 phase increased with the extrusion temperature rising .The AZT802 alloy extruded at 380 ℃ and aged at 175 ℃ for 3 h possessed the best mechanical properties .