【摘要】 对钼合金进行了应力控制高温低周等温疲劳和同相位热机械疲劳试验。对于等温疲劳试验选取的实验温度为３５０℃和５００℃，对于热机械疲劳试验循环温度范围为３５０℃－５００℃。根据采集的材料应力－应变响应和循环破坏周数，可以看出温度的变化对材料疲劳寿命产生很大影响，当温度循环和应力循环叠加时，会加重损伤的程度。对循环回线的分析表明，在每一种疲劳试验过程中均发生材料循环软化和循环蠕变现象。对破坏试件的微观结构分析表明，在高应力循环条件下，钼合金的破坏基本上是脆断过程。更多还原

【Abstract】 High temperature isothermal mechanical fatigue and in phase thermomechanical fatigue (TMF) tests in stress control were carried out on a molybdenum alloy. Two temperature levels of 350 and 500℃ were applied to isothermal fatigue tests and a temperature interval of 350 500℃ to TMF tests. The fatigue lives obtained in the in phase TMF tests is lower than the ones obtained in the isothermal mechanical tests at the same stress amplitude. It appears that an additional damage produced by the reaction of mechanical stress cycles and temperature cycles in TMF situation. Ratching phenomenon occurred during the tests with an increasing creep rate and it was dependent on temperature and load amplitude. The observations of the microstructure of the damaged specimens demonstrated that the fracture was a brittle process under higher cyclic stress conditions. A simple model of lifetime prediction was developed and it is based on Woehler Miner law. The lifetime prediction gives results corresponding to experimental data.更多还原