静液挤压及退火处理对AZ80镁合金组织及力学性能的影响
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摘要
通过不同状态AZ80镁合金的金相组织观察、力学性能试验和断口SEM分析,研究了静液挤压及退火热处理对AZ80镁合金组织及力学性能的影响。结果表明:经静液挤压后,镁合金组织发生动态再结晶,生成细小再结晶晶粒,再结晶晶粒尺寸10μm左右,镁合金抗拉及屈服强度明显提高,分别达到325 MPa和241 MPa。退火热处理后,在高温热能的驱动下镁合金组织发生了静态再结晶,同时位错能得到释放,使镁合金伸长率大幅度提高,达到8.1%。均匀化态的镁合金断裂属于韧性和脆性混合型断裂;挤压态镁合金断裂是脆性解理断裂;退火热处理态镁合金表现为沿晶脆性断裂,但与挤压态相比,断口有向韧性断裂过渡的倾向。
The effects of hydrostatic extrusion and annealing heat treatment on the microstructure and mechanical properties of AZ80 magnesium alloy were studied by metallographic observation, mechanical properties test and fracture SEM analysis. The results show that, after hydrostatic extrusion, the microstructure of magnesium alloy is recrystallized dynamically and the fine recrystallized grains are formed. The size of recrystallization grain is about 10 μm. The tensile strength and yield strength of magnesium alloy increase obviously, reaching 325 MPa and 241 MPa, respectively. After annealing heat treatment,static recrystallization occurs in the microstructure of magnesium alloy driven by high temperature heat energy. At the same time, dislocation energy is released, and the elongation of magnesium alloy increases to 8.1%. The fracture of homogeneous magnesium alloy belongs to ductile and brittle mixed fracture, and the extruded magnesium alloy fracture is brittle cleavage fracture. The annealed magnesium alloy exhibits brittle fracture along the grain, but the fracture surface tends to transition to ductile fracture in comparison with the extruded alloy.
The effects of hydrostatic extrusion and annealing heat treatment on the microstructure and mechanical properties of AZ80 magnesium alloy were studied by metallographic observation, mechanical properties test and fracture SEM analysis. The results show that, after hydrostatic extrusion, the microstructure of magnesium alloy is recrystallized dynamically and the fine recrystallized grains are formed. The size of recrystallization grain is about 10 μm. The tensile strength and yield strength of magnesium alloy increase obviously, reaching 325 MPa and 241 MPa, respectively. After annealing heat treatment,static recrystallization occurs in the microstructure of magnesium alloy driven by high temperature heat energy. At the same time, dislocation energy is released, and the elongation of magnesium alloy increases to 8.1%. The fracture of homogeneous magnesium alloy belongs to ductile and brittle mixed fracture, and the extruded magnesium alloy fracture is brittle cleavage fracture. The annealed magnesium alloy exhibits brittle fracture along the grain, but the fracture surface tends to transition to ductile fracture in comparison with the extruded alloy.
引文
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[2]Wu D,Chen R S,Ke W.Microstructure and mechanical properties of a sand-cast Mg-Nd-Zn alloy[J].Materials&Design,2014,58(6):324-331.
[3]Miura H,Maruoka T,Yang X,et al.Microstructure and mechanical properties of multi-directionally forged Mg-Al-Zn alloy[J].Scripta Materialia,2012,66(1):49-51.
[4]吴志林,赵言宝,袁人枢,等.镁合金管材静液挤压应用研究的关键问题探讨[J].热加工工艺,2015,44(13):105-108.
[5]Nie J F.Effects of precipitate shape and orientation on dispersion strengthening in magnesium alloys[J].Scripta Materialia,2003,48(8):1009-1015.
[6]赵根发,王忠堂,刘劲松,等.AZ80镁合金管材热挤压工艺及组织性能研究[J].沈阳理工大学学报,2010,29(6):55-58.
[7]刘春海,张振栋.热处理对反向挤压AZ80镁合金组织与性能的影响[J].材料与冶金学报,2014,13(4):262-265.
[8]黄宣彬.AZ80镁合金超高压静液挤压成形工艺及性能研究[D].南京:南京理工大学,2017.
[9]王岚,杨平,李长荣.金相试验技术[M].北京:冶金工业出版社,2010.
[10]沈骏,颜银标,任豪.多向挤压对AZ80镁合金组织与性能的影响[J].有色金属工程,2014,4(6):5-7.
[11]李艳辉,李保成,尹丛娟.时效处理对AZ80镁合金组织与性能的影响[J].热加工工艺,2009,38(10):172-174.
[12]郭学锋,杨文朋,任昉,等.镁合金的塑性变形与强化机理[J].热加工工艺,2012,41(24):7-12.
[13]王迎新.Mg-Al合金晶粒细化、热变形行为及加工工艺的研究[D].上海:上海交通大学,2006.
[14]任林昌.ZA52镁合金细化及半固态成形研究[D].兰州:兰州理工大学,2017.