Creep Void Growth Simulation of Local Area in a Steam Turbine Rotor
Creep Void Growth Simulation of Local Area in a Steam Turbine Rotor
复制标题
汽轮机转子局部区域的蠕变空洞生长模拟
DOI：
10.2472/jsms.56.100
复制
发表时间：
2007
期刊：
影响因子：
--
通讯作者：
T. Ogata
中科院分区：
文献类型：
--
作者：
T. Ogata
为了降低老化火电厂高温部件的维护成本，有必要提高剩余寿命评估方法的准确性。蒸汽涡轮机转子等高温部件在蠕变载荷条件下运行，蠕变空洞在晶界上产生并生长。开发空洞增长预测方法对于这些组件的可靠维护非常重要。本研究的目的是阐明涡轮转子材料在蠕变载荷条件下的空洞生长行为，并开发空洞生长模拟程序，可以定量预测实际运行条件下部件的损伤扩展过程。对1Cr-Mo-V锻造材料进行了蠕变试验，并通过中断试验制作了蠕变损伤试样。从蠕变损伤试件的观察来看，损伤初期，晶界上开始出现球形空洞，并长大至长度为2μm，然后这些空洞变为裂纹状并长大，直至长度达到10μm左右。最后，裂纹状空隙相互结合，沿晶界形成一条微裂纹。基于空洞生长机理的理论考虑，可以得出结论，在约束条件下，空洞生长速率受扩散和幂律蠕变控制。通过这些讨论，通过修改传统模型，提出了一种新的空洞增长模型。通过将空洞增长模型合并到个人计算机中，开发了空洞增长模拟程序。证实仿真程序很好地预测了实验中蠕变条件下的空洞生长过程。该模拟程序还用于预测实际汽轮机转子在运行过程中的蠕变空洞增长行为。
In order to reduce maintenance cost of high temperature components in aged thermal power plants, it is necessary to improve accuracy of remaining life assessment methods. High temperature components such as steam turbine rotors are operated under creep loading condition where creep voids initiate and grow on grain boundaries. Development of a void growth prediction method is important for reliable maintenance of these components. Purposes of this study are to clarify void growth behavior of a turbine rotor material under creep loading condition, and to develop void growth simulation program that can predict damage extension process in the components under actual operating condition quantitatively. Creep tests have been conducted on a 1Cr-Mo-V forging material and creep damaged specimens were produced by interrupting the tests. From observation of the creep damaged specimen, spherical shape voids initiate and grow up to their length of 2μm on the grain boundary at initial stage of damage, and then these voids change their shape to crack-like to grow until their length reaches around 10μm. Finally, crack-like voids coalesce each other to form one micro crack along grain boundary. It can be concluded that void growth rate is controlled by diffusion and power law creep under constrained condition based on theoretical consideration of void growth mechanism. Through these discussions, a new void growth model was proposed by modifying conventional models. A void growth simulation program was developed by incorporating the void growth model into a personal computer. It was confirmed that void growth process under the creep condition in the experiment was well predicted by the simulation program. The simulation program was also applied to predict creep void growth behavior in an actual steam turbine rotor during operation.