(湖南大學(xué) 材料科學(xué)與工程學(xué)院，長沙410082)
摘 要: 采用空氣錘對AZ31合金在350 ℃以Δε=0.22的道次應(yīng)變量進行1~12道次多向鍛造變形，并對其組織和性能進行測試。結(jié)果表明：合金高應(yīng)變速率多向鍛造(HSRTF)組織演變分為兩個階段，累積應(yīng)變∑Δε＜1.32時為晶粒細(xì)化階段，其主要機制為孿晶再結(jié)晶；累積應(yīng)變∑Δε＞1.32時為晶粒長大階段，其主要機制為熱激活長大。利用大量的孿晶對再結(jié)晶的促進作用，高應(yīng)變速率多向鍛造工藝可快速生產(chǎn)細(xì)晶粒高性能AZ31變形鎂合金錠坯，累積應(yīng)變∑Δε=1.32時，可獲得組織均勻、平均晶粒度為7.4 μm的鍛坯，其抗拉強度、屈服強度和伸長率分別為313 MPa、209 MPa和28.6%。
關(guān)鍵字: AZ31鎂合金；高應(yīng)變速率多向鍛造；顯微組織；孿晶再結(jié)晶；力學(xué)性能
（College of Materials Science and Engineering, Hunan University, Changsha 410082, China）
Abstract:High strain rate triaxial-forging (HSRTF) of AZ31 magnesium alloy was conducted by the pneumatic power hammer at 350 ℃ with a pass strain of 0.22, and the microstructure and mechanical properties of wrought alloy with the different accumulated strains was studied. The results show that the microstructure evolution is divided into two stages according to the different mechanisms: twin DRX (Dynamic recrystallization) induced grain refinement with the accumulated strain ∑Δε lower than 1.32 and thermal activated grain growth with the accumulated strain ∑Δε higher than 1.32. HSRTF is an efficient technique for the preparation of the fine-grained AZ31 alloys with perfect mechanical properties ascribe to the auxo-action of twins on DRX during high strain rate deformation. And a homogeneous structure with the average grain size of 7.4μm can be obtained with the accumulated strain ∑Δε of 1.32, which has the ultimate tensile strength (UTS), yield strength (YS) and elongation of 313 MPa, 209 MPa and 28.6%, respectively.
Key words: AZ31 magnesium alloy; high strain rate triaxial-forging; microstructure; twin dynamic recrystallization; mechanical property
