CAJ | 학술논문

通过对挤压坯预成形AZ81镁合金进行模压成形及随后的时效处理,研究了形变及时效过程中显微组织及力学性能的变化规律.结果表明:时效温度埘AZ81镁合金力学性能及显微组织的影响较大,随时效温度升高至200℃,第二相的析出速度加快,且析出相分布变得均匀,细小析出相呈弥散状态分布于晶界上;随时效时间的延长.β-Mg17Al12析出相逐渐增多,当时效温度为200℃、时效20h时,晶界大多被析出物所掩盖,晶粒内充满大量点针状析出相,合金显微组织的各向异性得以消除,成分较为均匀,进一步提高了模压成形镁合金的力学性能,经400℃模压成形及200℃×20 h的时效处理后,其抗拉强度可达358.5 MPa,屈服强度达到260.7 MPa,伸长率为9.8%.
통과대제압배예성형AZ81미합금진행모압성형급수후적시효처리,연구료형변급시효과정중현미조직급역학성능적변화규률.결과표명:시효온도시AZ81미합금역학성능급현미조직적영향교대,수시효온도승고지200℃,제이상적석출속도가쾌,차석출상분포변득균균,세소석출상정미산상태분포우정계상;수시효시간적연장.β-Mg17Al12석출상축점증다,당시효온도위200℃、시효20h시,정계대다피석출물소엄개,정립내충만대량점침상석출상,합금현미조직적각향이성득이소제,성분교위균균,진일보제고료모압성형미합금적역학성능,경400℃모압성형급200℃×20 h적시효처리후,기항랍강도가체358.5 MPa,굴복강도체도260.7 MPa,신장솔위9.8%.
The change rules of microstructure and mechanical properties of AZ81 alloy during close-die hot-pressing of extruded preform and succedent aging were investigated.The results show that when the aging temperature goes to 200℃.the speed of second phase decomposition and precipitation goes up.The distribution of precipitated phase gets uniform,the precipitated phase distributes in grain boudary are in dispersed state;when aging time expanding,β-Mg17Al12 phase increases gradually;when aging at 200℃ for 20 h,the most and a majority of them are exiguous sheets,the component is uniform,it makes the mechanical properties of material getting best.Grain boundary is shielded by large quantity precipitate phases and gram inner distributes lots of spotted-niddle precipitate phases,but anisotropic property of AZ81 alloy are erased and its mechanical properties are improved.The tensile strength of AZ81 alloy by hot pressing forming at 400℃and aging at200℃ for 20 h is about 358.5 MPa,yield strength about 260.8 MPa,and elongation about 9.8%.