超声深滚处理改善预腐蚀7A52-CZ铝合金疲劳性能机理  

Mechanism on Improvement of Fatigue Performance of Pre-corroded 7A52-CZ Aluminum Alloy by Ultrasonic Deep Rolling Treatment

作　　者：朱有利[1] 叶雄林[1] 何嘉武[2] 李礼[1] 黄元林[1] 

机构地区：[1]装甲兵工程学院装备再制造工程系,北京100072 [2]装甲兵工程学院科研部,北京100072

出　　处：《材料工程》2009年第1期41-45,共5页Journal of Materials Engineering

摘　　要：研究了超声深滚(UDR)处理对预腐蚀7A52-CZ铝合金疲劳性能的作用。7A52铝合金试样在剥蚀腐蚀溶液中浸泡不同时间后进行了超声深滚处理。分别对未腐蚀试样、腐蚀试样和腐蚀+UDR处理试样进行了疲劳试验,用XRD应力测试和扫描电镜等方法分析了UDR处理前后试样的残余应力和断口形貌,并对疲劳断口进行了分析。结果表明:UDR处理在铝合金中引入超过1mm深的残余压应力层,延长了7A52的预腐蚀疲劳寿命。对于腐蚀较轻的试样,UDR处理使裂纹源在表层下残余压应力和拉应力过渡区产生,延长了疲劳裂纹萌生寿命;对腐蚀较重试样,疲劳裂纹仍从晶间腐蚀处形核,但由于引入残余压应力及腐蚀裂纹的部分愈合效应,仍在很大程度上改善了7A52的预腐蚀疲劳寿命。The effects of an ultrasonic deep rolling （UDR） treatment on the fatigue behavior of pre- corroded 7A52-CZ aluminum alloys were investigated. 7A52 aluminum alloy specimens were corroded in exfoliation corrosion （EXCO） solution at different durations. Some corroded specimens were treated by UDR. Fatigue tests were carried out for the uncorroded, corroded and UDR treated specimens. By means of X-ray diffraction stress measurements and scanning electron microscopy （SEM）, residual stress and fractograph of 7A52 aluminum alloys with and without UDR treatment were analyzed. The results indicated that UDR produced compressive residual stresses with depth approaching 1mm. UDR treatment can extend the fatigue life of the pre-corroded 7A52 specimens to a large extent, depending on the level of corrosion and UDR parameter. For the light corroded specimens, UDR treatment changed the fatigue crack nucleation site from surface to the transition zone between the compressive residual stresses and tensile stresses, resulted in a much longer fatigue life. For the severely corroded specimens, the crack still nucleated by intergranular cracking, however, due to the compressive residual stresses introduced and the closure of the corrosion pits and corrosion microcracks, UDR treatment still improved fatigue performance of the pre-corroded 7A52 aluminum alloy substantially.

关 键 词：超声深滚处理 铝合金 预腐蚀 疲劳 

分 类 号：TG146.21[一般工业技术—材料科学与工程] V216.3[金属学及工艺—金属材料]