CREEP CRACK GROWTH BEHAVIOR OF ALLOY 718 DURING HIGH TEMPERATURE EXPOSURE

查看全文 作　　者：J.X.Dong M.C.Zhang Y.P.Zeng [1]X.S.Xie 机构地区：[1]DepartmentofMaterialScience,UniversityofScienceandTechnologyBeijing,Beijing100083,China 出　　处：《Acta Metallurgica Sinica(English Letters)》索引2005年第18卷第2期,共9页 基　　金：The authors thank Ladish Co.,Inc.to support the test samples for this analysis.And this work was supported by the National Natural Science Foundation of China(No.50171005);the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institutions of MOE to support it. 摘　　要：Alloy 718 is a precipitation strengthened nickel-based superalloy based on the precipitation of γ″-Ni3Nb (DO22 structure) and γ′-Ni3(Al,Ti) (L12 structure) phases. Creep crack growth rate (CCGR) was investigated after high temperature exposure at 593, 650 and 677℃ for 2000h in Alloy 718. In addition to the coalescence of γ′/ γ″ and the amount increasing of δ phase, the existence of a bcc chromium enriched α-Cr phase was observed by SEM, and the weight fraction of α-Cr and other phases were determined by chemical phase analysis methods. The CCGR behavior and regulation have been analyzed by means of strength and structure analysis approaches. The experimental results show higher the exposure temperature and longer the exposure time, lower the CCGR. This is probably attributed to the interaction of material softening and brittling due to complex structure changes during high temperature exposure. Therefore, despite α-Cr phase formation and amount enhancement were run in this test range. It seems to us a small amount of α-Cr will be not harmful for creep crack propagation resistance, which is critical for disk application in aircraft and land-based gas turbine. 关 键 词：718合金 沉淀增强 镍基超合金 蠕变断裂 α-铬相