K40S钴基高温合金高温高周疲劳行为

High temperature high cycle fatigue behavior of K40S cobalt-b ase superalloy

研究了K4 0S合金 70 0℃和 90 0℃高周疲劳行为。结果表明 :K4 0S合金具有低的高温疲劳缺口敏感性 ,合金在 70 0℃和 90 0℃温度条件下的疲劳缺口敏感性分别为 0 .0 2 5和 0 .0 35 ,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M2 3 C6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。K4 0S合金 70 0℃高周疲劳断裂机制主要为机械疲劳断裂 ,而在 90

High temperature high cycle fatigue properties and fractu re behavior of K40S cobalt-base superalloy at 700 ℃ and 900 ℃ under experimen tal 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 fa tigue resistance is attributed to the secondary carbides M 23 C 6 dynamic a ging hardening effects. At 700 ℃, high cycle fatigue failure of K40S alloy is in form of mechanical fatigue, while at 900 ℃, the fatigue failure results fro m the interaction of mechanical fatigue and environmental oxidation.