Influence of dynamic strain aging (DSA) under sequential low cycle fatigue (LCF) and high cycle fatigue (HCF) loading was investigated by conducting HCF tests on specimens subjected to prior LCF cycling over a wide range of temperature from 573 to 973 K. DSA was found to be pronounced at 823–873 K depending on the magnitude of the stress employed under HCF cycling. DSA was seen to have contrasting implications under LCF and HCF deformation resulting in an anomalous fatigue behavior in terms of remnant HCF life under LCF-HCF interaction. LCF-HCF interaction was found to be pronounced at intermediate levels of prior LCF exposure, where the remnant HCF life is dictated by competitive damage mechanism resulting from the influence of DSA under LCF as well as HCF. Detailed fracture surface examination revealed that extensive hardening associated with DSA leads to an extended zone of faceted appearance with river markings (Stage-I crack) under HCF cycling (with or without LCF exposure). This reduces the crack growth rate, delaying the transition of crack from Stage-I to Stage-II, thereby leading to an extension of life in such cases. On the other hand, a highly striated fracture surface indicating a quick transition in crack from Stage-I to Stage-II, was observed for loading conditions with minimal or no influence of DSA, thus leading to lower life compared to the previous case.

通过在573至973 K的宽温度范围内对经过先前LCF循环的样品进行HCF测试，研究了动态应变时效（DSA）对连续低循环疲劳（LCF）和高循环疲劳（HCF）负载的影响。被发现在823–873 K时明显，这取决于HCF循环所采用的应力大小。观察到DSA在LCF和HCF变形下具有相反的含义，导致在LCF-HCF相互作用下残留的HCF寿命方面出现了异常的疲劳行为。发现LCF-HCF相互作用在先前LCF暴露的中间水平上是显着的，其中残留的HCF寿命由DSA在LCF以及HCF的影响下产生的竞争性损害机制决定。详细的断裂表面检查表明，在HCF循环（有或没有LCF暴露）下，与DSA相关的广泛硬化导致带有河痕（I级裂纹）的多面外观扩展区域。这降低了裂纹的生长速率，延迟了裂纹从阶段I到阶段II的过渡，从而延长了这种情况下的寿命。另一方面，在DSA影响最小或没有DSA影响的载荷条件下，观察到高度条纹状的断裂表面，表明裂纹从I阶段快速过渡到II阶段，因此与之前的情况相比寿命降低。因此，在这种情况下会延长寿命。另一方面，在DSA影响最小或没有DSA影响的载荷条件下，观察到高度条纹状的断裂表面，表明裂纹从I阶段快速过渡到II阶段，因此与之前的情况相比寿命降低。因此，在这种情况下会延长寿命。另一方面，在DSA影响最小或没有DSA影响的载荷条件下，观察到高度条纹状的断裂表面，表明裂纹从I阶段快速过渡到II阶段，因此与之前的情况相比寿命降低。