Evaluation of oxidation related damage caused to a gas turbine disc alloy between 700 and 800°C
Evaluation of oxidation related damage caused to a gas turbine disc alloy between 700 and 800°C
复制标题
评估 700 至 800°C 之间对燃气轮机盘合金造成的氧化相关损坏
DOI：
10.3184/096034009x465202
复制
发表时间：
2009
影响因子：
1.3
通讯作者：
Mark Hardy
中科院分区：
文献类型：
--
作者：
A. Encinas;N. Simms;John Nicholls;G. L. Drew;J. Leggett;Mark Hardy
本文介绍了一种新的镍基盘合金（RR 1000）在中温下的氧化行为的研究结果。使用热微量天平在700 - 800°C范围内的温度下进行等温暴露，暴露长达200小时。在700和750°C下进行循环氧化暴露长达1000小时，循环100小时，使用质量变化来监测材料性能。获得的质量增加数据已被用于推导氧化反应速率参数，使用已建立的方法，抛物线速率常数在700°C下的1.4×10-5 mg 2/cm 4/h和800°C下的8.4×10-4 mg 2/cm 4/h之间变化。表面氧化物进行了初步分析，使用扫描电子显微镜/能量色散X射线分析（SEM/EDX）和X射线衍射（XRD）技术。结果表明，在这些暴露过程中，样品表面形成了缓慢生长的富铬氧化物膜。使用聚焦离子束（FIB）系统进行了更详细的研究，通过氧化层和下面的合金的横截面。对观察到的薄氧化物的测量显示厚度范围从0.08μm到1.9μm，这与收集的质量变化数据一致。然而，FIB检查也显示了显着的亚表面损伤，其中包含的晶界孔，第二相耗尽区，和晶粒再结晶的混合物。这些亚表面损伤区的深度大于氧化层的厚度，并且被认为对该盘合金的疲劳性能具有重大影响。FIB系统的使用使得能够表征氧化层和亚表面损伤区的发展与暴露时间和温度的函数关系。
Abstract This paper presents the results of a study targeted at characterising the oxidation behaviour of a new nickel based disc alloy (RR1000) at intermediate temperatures. Isothermal exposures were carried out using a thermo-microbalance at temperatures in the range 700 – 800°C for exposures up to 200 hours. Cyclic oxidation exposures were carried out at, 700 and 750°C for up to 1000 hours with 100 hour cycles, using mass change to monitor the materials performance. The mass gain data obtained have been used to derive oxidation reaction rate parameters, using established methodologies, with parabolic rate constants varying between 1.4×10–5 mg2/cm4/h at 700°C and 8.4×10–4 mg2/cm4/h at 800°C. Surface oxides were initially analysed using scanning electron microscope/energy dispersive X-ray analysis (SEM/EDX) and X-ray diffraction (XRD) techniques. The results showed that slowly-growing chromium-rich oxide scales had formed on the surface of the samples during these exposures. A more detailed study of cross-sections through the oxide layers and underlying alloy was undertaken using a focused ion beam (FIB) system. Measurements of the thin oxides observed showed ranges of thicknesses from 0.08μm up to 1.9μm, that were consistent with the mass change data gathered. However, the FIB examinations also revealed significant sub-surface damage that contained a mixture of grain boundary pores, a second phase depletion zone, and grain recrystallisation. The depth of these sub-surface damage zones was greater than the thickness of the oxide layers and is believed to have a major impact on the fatigue performance of this disc alloy. The use of the FIB system has enabled characterisation of the development of both the oxide layers and sub-surface damage zones as a function of exposure time and temperature.