固溶预处理对AZ80镁合金流变行为和组织的影响

Effect of pre-solution treatment on rheological behavior and microstructure of AZ80 magnesium alloy

对AZ80镁合金在等温热压缩前采用固溶预处理工艺,通过等温热压缩试验、金相显微镜、扫描电镜、透射电镜、X射线衍射分析、电子背散射衍射等多种试验与分析手段,分析了固溶预处理对AZ80镁合金在不同等温压缩条件下的流变行为和再结晶行为的影响。结果表明:经过410℃×2 h固溶预处理后的材料,组织中粗大的Mg17Al12相溶解,在各变形条件下流变应力整体上均低于同条件下的初始锻态材料,峰值流变应力降低10~30 MPa,表明固溶预处理使材料在热压缩过程中得到了一定软化,提高了加工时的塑性变形能力。410℃×2 h固溶预处理后,在300℃及以下的变形中温区,材料的再结晶机制由不连续动态再结晶转变为连续动态再结晶,使再结晶体积分数明显提高,晶粒细化更充分,塑性变形能力提高。

Pre-solution treatment was conducted on AZ80 magnesium alloy before isothermal hot compression. The influences of pre-solution treatment on the recrystallization,microstructure and rheological behavior of AZ80 magnesium alloy under different compression conditions were compared and analyzed by means of isothermal hot compression experiment,metallographic microscope,scanning electron microscope,transmission electron microscope,X-ray diffraction analysis and electron backscattering diffraction. The results show that after the presolution treatment of 410 ℃ × 2 h,the coarse Mg17Al12 phase in the initial forged material has dissolved,and during the isothermal hot compression tests,the rheological stress of the material after pre-solution treatment is lower on the whole than that of the initial forged material under the same compression condition,i. e.,the peak stress is decreased by 10-30 MPa,indicating that the pre-solution treatment softens the material in the process of isothermal hot compression and thus improves the plastic deformation ability during the processing. After the pre-solution treatment of 410 ℃ × 2 h,and in the deformation temperature zone of 300 ℃ and below,the recrystallization mechanism of the material changes from discontinuous dynamic recrystallization into continuous dynamic recrystallization,and the recrystallization volume fraction increases significantly,the grains are fully refined and the plasticity is improved as well.