2E12铝合金的疲劳性能与裂纹扩展行为
The Fatigue Performance and Fatigue Crack Propagation Behavior of 2E12 Al Alloy
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摘要: 研究了2E12合金在不同应力水平下的疲劳性能及疲劳裂纹扩展速率,采用透射电镜和扫描电镜观察了该合金的微观组织和断口形貌特征.结果表明：高纯2E12合金具有良好的耐损伤疲劳性能,当应力比R=0.1时,疲劳强度σ=172 MPa,R=0.5时的疲劳强度σ=280 MPa,比R=0.1时提高了60%,缺口的存在降低了疲劳强度.R=0.1,ΔK=30 MPa·m1/2时,da/dN约为2.7×10-3 mm/周,比国产2024合金裂纹扩展速率(6.5×10-3 mm/周)低60%左右.2E12合金疲劳断口由裂纹源区、裂纹扩展区及瞬断区三部分组成,裂纹萌生一般位于试样表面应力集中处或不同类型的缺陷部位.Abstract: The fatigue performance and fatigue crack growth rate in 2E12 alloy were studied under different stress radio.At the same time,TEM and SEM were applied to analyze the microstructures and fracture appearance.It is shown that the excellent fatigue damage tolerance would be exhibited in 2E12 alloy.On the condition of R=0.1,the fatigue limit is 172 MPa,and the value would be increased by 60% on the condition of R=0.5.These existing notches resulted in reduction of fatigue limit of this alloy.On the condition of R=0.1,ΔK=30 MPa·m1/2,the fatigue crack growth rate (da/dN) would be 2.7×10-3 mm/cycle,which is lower by 60% than that of 2024 alloy.The fracture appearance of 2E12 alloy consist of fatigue crack initiation zone,fatigue crack propagation zone and final fracture zone.The locations of initial fatigue cracks generally are on the surface stress concentrated or on the different defects in this alloy.
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