高温合金热疲劳实验机的研制及实验研究

摘要

介绍了用于测试高温合金热疲劳性能的热疲劳实验机.该实验机主要用于定性地测量合金在某一条件下循环规定的次数后热疲劳裂纹扩展的长度,或热疲劳裂纹在扩展一定长度下循环的次数.该实验机的优点是:完全自动化、运行灵活、定位准确.通过对DZ951定向凝固镍基高温合金进行实验研究,表明该热疲劳实验机具有较好的稳定性和可靠性.DZ951合金主要通过铝和铬元素氧化,产生氧化孔洞.热疲劳裂纹通过孔洞相互连接萌生和扩展.合金具有两条热疲劳裂纹,且扩展具有一定方向,与枝晶生长方向成45°扩展.%A thermal fatigue machine which is used to test the thermal fatigue property of superalloy was introduced.The experimental machine was utilized to qualitatively test crack propagation length of thermal fatigue in the set cycles in some condition or the cycle numbers when crack propagates to a certain length.The advantages of the machine are complete automatization,flexible run,correct orientation.The experimental results for directionally solidified DZ951 nickel-base superalloy indicate that the machine has better stability and reliability.The initiation and propagation of thermal fatigue crack of the alloy is mainly by oxidation and join of oxidative cavity.The alloy has two cracks and the propagation direction of thermal fatigue crack has some crystal orientation.The angle between the propagation direction and the orientation of crystal growth is 45°.