(中國科學(xué)院 金屬研究所, 沈陽 110016)
摘 要: 研究了K40S合金700℃和900℃高周疲勞行為。 結(jié)果表明： K40S合金具有低的高溫疲勞缺口敏感性，合金在700℃和900℃溫度條件下的疲勞缺口敏感性分別為0.025和0.035， 合金低的缺口敏感性主要歸因于合金良好的高溫塑性。二次碳化物M23C6的高溫動態(tài)時效強化有效地強化了合金基體， 提高合金的形變抗力，使合金具有較高的疲勞強度。 K40S合金700℃高周疲勞斷裂機制主要為機械疲勞斷裂，而在900℃溫度條件下則為機械疲勞與高溫環(huán)境氧化共同作用的, 結(jié)果。
關(guān)鍵字: 高周疲勞; 疲勞缺口敏感性; 疲勞強度; 環(huán)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
