在温度为20，120，250，350，450℃和应变幅为0.5%，0.7%，1.0%，1.5%，2.0%条件下对热采井套管用80SH钢进行低周疲劳试验，研究了在动态应变时效（DSA）影响下的低周疲劳行为；基于低周疲劳试验数据，建立DSA影响下低周疲劳寿命与应变幅间的关系模型。结果表明：80SH钢在350℃时具有显著的DSA特性，此时80SH钢在高温低周疲劳过程中出现显著的二次硬化行为，导致晶粒内的位错塞积，阻碍裂纹的扩展，出现循环硬化，从而在疲劳断口中形成解理台阶和大量的二次裂纹；在DSA显著温度区间，疲劳寿命与弹性应变在双对数坐标系中呈双线性关系，而与塑性应变仍呈线性关系；Manson-Coffin线性模型和Basquin双线性模型的叠加能够较好描述DSA影响下80SH钢疲劳寿命与应变的关系。

Low cycle fatigue tests were conducted on 80SH steel for thermal recovery well casing at 20, 120, 250, 350, 450℃ and strain amplitudes of 0.5%, 0.7%, 1.0%, 1.5%, 2.0%. The low cycle fatigue behavior under the influence of dynamic strain aging (DSA) was studied. Based on low cycle fatigue test data, the relation model between low cycle fatigue life and strain amplitude under the influence of DSA was established. The results show that 80SH steel had significant DSA characteristics at 350℃; the significant secondary hardening behavior of 80SH steel during high temperature low cycle fatigue appeared, resulting in dislocation accumulation in grains which prevented crack propagation; then cyclic hardening occurred, resulting in cleavage steps and a large number of secondary cracks appeared in the low cycle fatigue fracture. In the DSA significant temperature range, fatigue life had bilinear relationship with elastic strain in the double logarithmic coordinate system, while had linear relationship with plastic strain. The superposition of Manson-Coffin linear model and Basquin bilinear model could better describe the relation between fatigue life and strain of 80SH steel under the influence of DSA.