P92钢应变速率相关的高温低周疲劳行为研究  

Experimental study on strain rate-dependent low cycle fatigue behavior of P92 steel at high temperature

作　　者：张尚林 轩福贞[2] 罗英[1] 邱天[1] 邱阳[1] 胡甜 ZHANG Shanglin;XUAN Fuzhen;LUO Ying;QIU Tian;QIU Yang;HU Tian(Science and Technology on Reactor System Design Technology Laboratory,Nuclear Power Institute of China,Chengdu 610213,China;East China University of Science and Technology,School of Mechanical and Power Engineering,Shanghai 200237,China)

机构地区：[1]中国核动力研究设计院核反应堆系统设计技术国家级重点实验室,成都610213 [2]华东理工大学机械与动力工程学院,上海200237

出　　处：《压力容器》2021年第1期1-8,14,共9页Pressure Vessel Technology

基　　金：国家自然科学基金项目(51475167)。

摘　　要：随着电站设备向高参数、大型化方向发展,高温低周疲劳问题成为威胁关键设备安全服役的重要因素。针对电站设备广泛应用的P92钢,开展了不同应变速率的625℃高温下的低周疲劳试验,研究对称和非对称应变速率下的循环变形行为。结果表明,P92钢高温低周疲劳响应表现出明显的应变速率敏感性。随着应变速率降低,加载时间变长,蠕变变形增加,从而导致材料循环软化加速,疲劳寿命缩短。通过应力-应变滞回环分析发现,P92钢在反向卸载初始阶段发生蠕变变形。同时,随着应变速率的降低,循环过程中的应变硬化程度也随之降低。此外,非对称应变速率循环(慢-快)工况下疲劳寿命最短,慢拉伸应变速率引起的蠕变损伤加速材料的弱化,蠕变损伤和疲劳损伤的交互作用是高温疲劳破坏的主要原因,尤其在低应变速率下蠕变损伤的贡献更加明显。The high-temperature low-cycle fatigue damage has become an important factor that threatens the service safety of critical equipments used in power industry as the power plant develops to higher parameter and larger scale.In present study,the low cycle fatigue tests of P92 steel widely used in power station equipment were conducted under different strain rates at 625℃,and its cyclic deformation behavior under symmetric and asymmetric strain rates.The results show that the fatigue response of P92 steel at high temperature presents strong strain rate dependence.With the decrease of strain rate,increase of loading period and accumulation of creep deformation,it was observed that the cyclic softening was accelerated and the fatigue life was reduced.Through the stress-strain hysteresis loop analysis,it was found that the creep deformation occurred at the initial stage of unloading stage.At the same time,the degree of strain hardening decreases with the decrease of strain rate in the cyclic process.Besides,the fatigue life under the cyclic condition of asymmetric strain rate(slow-fast)was the shortest,the creep damage caused by slow strain rate accelerated the material weakening.The interaction of creep damage and fatigue damage was the dominated damage mechanism under high temperature low cycle fatigue,especially the contribution of creep damage at low strain rate was more obvious.

关 键 词：P92钢 高温 低周疲劳 应变速率 

分 类 号：TH142.2[一般工业技术—材料科学与工程] TG144[机械工程—机械制造及自动化]