(中国科学院 金属研究所, 沈阳 110016)
摘 要: 研究了K40S合金700℃和900℃高周疲劳行为。 结果表明： K40S合金具有低的高温疲劳缺口敏感性，合金在700℃和900℃温度条件下的疲劳缺口敏感性分别为0.025和0.035， 合金低的缺口敏感性主要归因于合金良好的高温塑性。二次碳化物M23C6的高温动态时效强化有效地强化了合金基体， 提高合金的形变抗力，使合金具有较高的疲劳强度。 K40S合金700℃高周疲劳断裂机制主要为机械疲劳断裂，而在900℃温度条件下则为机械疲劳与高温环境氧化共同作用的, 结果。
关键字: 高周疲劳; 疲劳缺口敏感性; 疲劳强度; 环境氧化
（Institute of Metal Research, The Chinese Academy of Sciences,
Shenyang 110016, China）
Abstract:High temperature high cycle fatigue properties and fracture behavior of K40S cobalt-base superalloy at 700℃ and 900℃ under experimental air conditions were investigated. The results show that, due to the superior high temperature ductility, K40S alloy exhibits low fatigue notch sensibility, 0.025 and 0.035 at 700℃ and 900℃ respectively. The excellent high cycle fatigue resistance is attributed to the secondary carbides M23C6 dynamic aging hardening effects. At 700℃, high cycle fatigue failure of K40S alloy is in form of mechanical fatigue, while at 900℃, the fatigue failure results from the interaction of mechanical fatigue and environmental oxidation.
Key words: high cycle fatigue; fatigue notch sensibility; fatigue resistance; environmental oxidation
