DZ125定向凝固合金的薄壁持久蠕变性能与断裂行为

采用薄壁试样研究高温试验条件下,试样壁厚对DZ125定向凝固合金向持久性能及其断裂特征的影响规律。结果表明:不同壁厚试样的持久寿命明显低于标准试样,表现出显著的薄壁效应,并且壁厚和持久寿命间存在明显的线性关系;薄壁试样持久断口边缘区域氧化严重,内部区域为微孔聚集型断裂;合金薄壁试样的持久断裂模式为"表面氧化-裂纹萌生-扩展"和"内部蠕变损伤"共同作用;合金在950℃/197 MPa下的蠕变性能表明,圆棒试样寿命明显高于薄壁试样寿命,0.6 mm厚度的薄壁试样寿命约为圆棒试样的50%,1.1 mm厚度的薄壁试样寿命约为圆棒试样的80%。

Stress Rupture and Creep Properties and Fracture Behavior of DZ125 Directionally Solidified Superalloy

The effects of wall thickness on the high-temperature stress rupture properties and fracture behavior of DZ125 directionally solidified superalloy were studied using thin-walled specimens. The result shows that the stress rupture life of the thin-walled specimens is significantly shorter than that of standard ones, indicating there is significant thin-wall effect. There is an obvious linear relationship between wall thickness and stress rupture life. The edge zone of the fracture surface of thin-walled specimens was seriously oxidized, while the inside zone was microvoid coalescence fracture. The fracture of thin-walled specimens is the coalescence of the " surface oxidation-crack initiating-crack growth” and " inside creep damage”. The creep property of the alloy under 197 MPa/950 ℃ shows that the stress rupture life of round specimens is significantly higher than that of thin-walled ones. The stress rupture life of the thin-walled specimens with the wall thickness of 0.6 mm and 1.1 mm is nearly 50% and 80% that of round specimen, respectively.