中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 13 No. 1 February 2003 |
（1. Institute of Metal Research, Chinese Academy of Sciences,
Shenyang 110016, China;
2. Shenyang Aero-engine Research Institute, Shenyang 110034, China）
Abstract:Fatigue crack propagation behavior of K40S cobalt-base superalloy under ambient atmosphere at 700℃ and 900℃ was investigated. The detailed fatigue crack propagation and fracture mechanism under the alternating loads were studied. The results show that, there is a defined threshold for K40S alloy at elevated temperatures. The fatigue threshold is 23.9MPa·m1/2 at 700℃ and 12MPa·m1/2 at 900℃. The significant decrease of the threshold with increasing temperature is associated with the oxidation induced embrittlement at crack tip. Observation on the fatigue fracture surfaces indicates a ductile fracture mechanism related to the fatigue crack growth.
Key words: cobalt-base superalloy; fatigue crack propagation; fatigue threshold; ductility
