环境和缺口形状对LY12CZ铝合金疲劳短裂纹扩展的影响  

EFFECT OF ENVIRONMENT AND NOTCH GEOMETRY ON SHORT FATIGUE CRACK GROWTH IN LY12CZ ALLOY

作　　者：常红[1] 王俭秋[1] 韩恩厚[1] 

机构地区：[1]中国科学院金属研究所,沈阳110016

出　　处：《机械强度》2004年第z1期39-41,共3页Journal of Mechanical Strength

摘　　要：研究不同环境下LY12CZ铝合金缺口短裂纹的扩展规律及缺口形状对短裂纹扩展规律的影响。相同ΔK水平下 ,短裂纹比长裂纹有更高的da dN值 ,3 .5 %NaCl溶液的加入 ,使锐、钝缺口短裂纹的da dN值都显著增加。但无论在何种环境下 ,锐、钝缺口短裂纹的扩展都呈明显的“马鞍”形状且溶液中的过渡裂纹尺寸高于空气中 ,用缺口根部塑性区大小、裂纹闭合效应和腐蚀介质的共同作用解释试验结果。尖缺口状态下 ,缺口根部塑性区尺寸很小 ,裂纹扩展主要受裂纹闭合影响 ;钝缺口状态下 ,缺口根部塑性区作用范围较大 。The notch short-crack fatigue propagation behavior of LY12CZ Aluminum alloy in air and in 3.5%NaCl solution has been investigated. The effect of notch geometry on short fatigue crack growth was also studied. The results show that the growth rates of nothched short cracks are much higher than those of long cracks at the same stress intensity factor range ΔK level, and the growth rates increase significantly in 3.5%NaCl solution compared with in air. The growth rates of both sharp and blunt notch crack decrease first to a minimum and then increase with increasing ΔK in two environmental conditions and the lengths of transitional cracks are longer in solution than in air. The results were explained in terms of the local plasticity at the notch root, crack closure and corrosion effect. Crack propagation in specimens with a sharp notch are mostly determined by crack closure because of the size of the plasticity is small. In the specimens with a blunt notch, the size of the plasticity is large which markedly affects the growth rate.

关 键 词：铝合金 腐蚀疲劳 短裂纹 缺口形状 裂纹闭合 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG115.57[金属学及工艺—金属材料] O346.22[金属学及工艺—金属学]