论文部分内容阅读
研究了3.5％NaCl溶液对恒应力强度因子范围△K控制下AISI 321不锈钢疲劳裂纹扩展过载行为的影响,与在空气中的结果比较表明,两种条件下存在相似的过载延缓效应,但是环境极大地削弱了过载对疲劳裂纹扩展的延缓效应,削弱程度随过载比不同而变化,以“损失循环数”表征约为40％—70％,以“过载影响区尺寸”表征则为30％—40％。分析表明,用“损失循环数”表征过载对裂纹扩展的延缓效应不够充分,无法区分环境对裂纹闭合的削弱和增强作用,“过载影响区尺寸”可以区分环境对过载塑性形变增强裂纹闭合的综合影响,对断口的SEM分析发现,过载造成的塑性形变在溶液中比在空气中受到更多的磨损,表明环境对过载延缓效应的削弱除了对裂尖的影响外,还包括对过载导致的塑性诱发裂纹闭合的影响。
The effect of 3.5% NaCl solution on the fatigue crack propagation behavior of AISI 321 stainless steel under constant stress intensity factor range △ K was studied. The results of air fatigue test showed that there was a similar overload delay effect under both conditions. However, The earth weakened the delaying effect of overload on the fatigue crack propagation. The degree of weakness varied with the overload ratio, and was characterized by a “loss cycle number” of about 40% -70% and that of “overload affected zone size” by 30% -40 %. The analysis shows that the “lag cycle number” characterizes the delayed effect of overloading on crack propagation is not sufficient enough to distinguish the weakening and enhancing effects of the environment on the crack closure. The “size of the overload influence zone” can distinguish the environment from the overload plastic deformation-enhanced crack closure synthesis The SEM analysis of the fracture shows that the plastic deformation caused by overload is more abated in solution than in air, indicating that the weakening of the environment on the overload delay effect, in addition to its effect on the crack tip, also includes plasticity due to overload Induced the effect of crack closure.