喷丸强化对7A12铝合金微观组织和疲劳性能的影响  

Effect of Shot Peening on Microstructure and Fatigue Life of 7A12 Aluminum

作　　者：汝继刚[1] 李超[1] 王亮[1] 李惠曲[1] 伊琳娜[1] 刘铭[1] 吴秀亮[1] 

机构地区：[1]北京航空材料研究院,北京100095

出　　处：《航空材料学报》2013年第6期51-56,共6页Journal of Aeronautical Materials

摘　　要：研究喷丸强化对高强铝合金7A12高周疲劳性能的影响。利用透射电镜(TEM)和扫描电镜(SEM)观察喷丸和未喷丸状态的微观组织和断口形貌,利用X射线(XRD)分析强化层残余应力分布情况。结果表明:喷丸强化使7A12铝合金疲劳强度提高了26%。喷丸强化可在材料表面引入残余压应力,并显著细化表层晶粒(形成亚晶)和实现位错增殖,且沿层深呈梯度变化特征。喷丸强化引起7A12铝合金疲劳强度提高可归因于喷丸造成的晶粒细化和位错增殖对疲劳裂纹萌生的有效抑制,以及喷丸引入的表面残余压应力对疲劳裂纹早期扩展的有效阻止作用。疲劳试样断口形貌证实喷丸强化后试样的疲劳裂纹扩展速率明显低于原始状态。The effect of shot peening as mechanical surface treatment on high cycle fatigue property of the high-strength aluminum alloy 7A12 was investigated.The microstructure and fracture of the alloy before and after shot peening were analyzed using SEM and TEM.The residual stress was investigated by XRD.The results show that shot peening increases the fatigue strength by 26％.Shot peening causes residual compressive stress layer in which grain is refined and dislocation is increment.The increase of fatigue strength after shot peening is attributed to the inhibition of fine crystalline zones and dislocations on fatigue crack initiation and the prevent propagation of residual compressive stress on early fatigue crack propagation.Analysis of the fracture surface reveals that residual compressive stress and microstructure are beneficial to the reduction of the fatigue crack growth rate.

关 键 词：喷丸强化 7A12铝合金 微观组织 疲劳性能 

分 类 号：TG146.21[一般工业技术—材料科学与工程]