Creep fracture mechanism of polycrystalline Ni-based superalloy with diffusion coatings
Diffusion coatings are widely used to increase oxidation and corrosion resistance of hot superalloy components for gas turbines. The aim of this study is to investigate the effect of coatings (NiAI and PtAl)on the creep fracture mechanism of samples with a substrate of IN792. The samples have been creep tested at two temperatures (850℃and 950℃ ) and different applied tensile stresses. until failure between 205 and 21000 hrs. The observation of cross-sections by SEM shows that the microstructural evolution in the coating is dependent on the diffusion of alloying elements in the sample. Furthermore the time and temperature induced growth of the coating is found to be controlled only by inward diffusion of Al. Grain-boundary cracking is the basic fracture mode in the substrate in all samples irrespective if the crack is initiated from coating or substrate. The analysis of microstructure shows that the diffusion coatings display two types of mechanical behavior - being easily plasticized or cracked - dependent on temperature and type of coating, and therefore can be considered as non-load carrying regions. After recalculating the creep stress to exclude the final effective coating thickness from the total sample thickness. the coated samples showed similar creep rupture behavior as the uncoated samples in the Larson-Miller diagram.
Creep Ni-based superalloy Diffusion coating Crack
Kang Yuam Ru Lin Peng Xin-Hai Li Lennart Johansson Sten Johansson Yan-dong Wang
Department of Management and Engineering,Linkoeping University,SE-58183 Linkoping,Sweden Siemens Industrial Turbomachinery AB,SE-61283 Finspang,Sweden Beijing Institute of Technology,Beijing 100081,China
国际会议
北京
英文
1-10
2013-06-16（万方平台首次上网日期，不代表论文的发表时间）