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研究了镍基定向凝固高温合金DK3和普通铸造合金K3在760℃应变控制和应力控制下的高温低周疲劳行为。结果表明:这两种合金的高温低周疲劳行为可以用常规的应力疲劳曲线来表征。DK3合金不存在“过渡疲劳寿命”N_T,K3合金则很低。在各种不同应变或应力水平下,DK3合金的低周疲劳寿命高于K3合金,当应力水平为785至980MPa时,其寿命约差1倍,当应力水平为490至685MPa时,则差2倍多。
The high temperature and low cycle fatigue behavior of the DK3 and the cast alloy K3 of the Ni-based directional solidification superalloy were investigated at 760 ℃ for strain control and stress control. The results show that the high temperature and low cycle fatigue behavior of the two alloys can be characterized by conventional stress fatigue curves. DK3 alloy does not exist “transition fatigue life” N_T, K3 alloy is very low. At various strain or stress levels, the DK3 alloy has a lower low-cycle fatigue life than K3 alloy, with a life expectancy about 1-fold when the stress level is between 785 and 980 MPa and a difference of 2 when the stress level is between 490 and 685 MPa More times.