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本文用中心缺口拉伸试样(CCT试样)测试了LY-12CS铝合金在室温空气和3.5%NaCl水溶液介质中三种载荷比(R=0,R=0.33,R=0.67)条件下的疲劳裂纹扩展门坎值ΔK_(th)及da/dN,结果表明:(1)在三种载荷比条件下,盐水介质比空气介质明显地降低了ΔK_(th)而提高了疲劳裂纹扩展速率da/dN。在我们试验的三种载荷比ΔK=7～15kg/mm~(3/2)范围内,盐水介质的da/dN是空气介质的1·6～3·4倍。(2)在两种介质中,随着载荷比R(或平均应力)的增加,门坎值ΔK_(th)下降而da/dN增加。
In this paper, the CCL specimens were used to test the mechanical properties of LY-12CS aluminum alloy under three loading conditions (R = 0, R = 0.33, R = 0.67) in room temperature air and 3.5% Fatigue crack growth threshold values ΔK th and da dN, the results show that: (1) Under three loading conditions, brine medium significantly reduces ΔK th (th) than the air medium and increases the fatigue crack growth rate da / dN. In the three load ratios ΔK = 7 ~ 15kg / mm ~ (3/2) we tested, the da / dN of brine medium is 1.6-3.4 times that of air medium. (2) In both media, as the load ratio R (or mean stress) increases, the threshold ΔK_ (th) decreases and da / dN increases.