摘要
超(超)临界汽轮机汽缸以镍基超高温合金作为紧固件材料,螺栓蠕变损伤的研究对超(超)临界机组的安全运行及维修具有重要意义。对镍基合金Nimonic 80A进行了550℃不同应力下单轴及空心螺栓的蠕变实验,引入应变阈值,结合Norton-Bailey-Kachanov蠕变方程,改进了蠕变损伤模型,模型能更准确描述蠕变全过程;修改有限元软件ABAQUS子程序,模拟了空心螺栓的蠕变过程。结果表明,空心螺栓蠕变断裂并不是在应力集中的螺纹处,而是在螺杆处,有限元计算结果与实验结果吻合较好。
Nickel based alloy will become one of the most common material of ultra-supercritical steam turbine cylinder case fasteners in future. It is important to study creep damage of bolts for ultra-supercritical generating units performance safely and service. Creep rupture experiments of Nimonic 80A uniaxial specimen and hollow bolts at 550℃ and different stress were carded out. Creep damage model was improved by inducting strain threshold value based on Norton-Bailey- Kachanov creep model, which was more exact to describe creep process. Creep behaviors of hollow bolt were simulated by ABAQUS based on reworking improved creep damage model of subroutine. It is indicated that creep rupture of hollow bolt is not taking place at screw thread where the stress concentrated, but taking place at the position of screw shaft. A good coincidence comparing the result calculated according to the theoretical model presented with finite element calculation can be observed.
出处
《中国电机工程学报》
EI
CSCD
北大核心
2007年第29期80-83,共4页
Proceedings of the CSEE
关键词
超(超)临界汽轮机
紧固螺栓
高温蠕变
蠕变损伤模型
应变阈值
断裂
ultra-supercritical steam turbine
fastening bolt creep at high temperature
creep damage model
strain threshold value
rupture
