片层厚度对损伤容限型TC21合金裂纹扩展速率的影响

Effect of Lamellar Thickness on Fatigue Crack Growth Rate of TC21 Alloy of Damage Tolerance

分别采用α+β锻造和β锻造方式制备了TC21合金90mm棒材,研究了两种加工方式下同规格棒材的裂纹扩展速率,分析了粗细两种片层结构对裂纹扩展速率的影响。结果表明:β锻造获得了细片层组织结构,具有较低的疲劳裂纹扩展速率;α+β锻造得到粗片层组织结构,裂纹扩展速率较快。疲劳裂纹扩展速率随着组织片层厚度的增加而加快。在疲劳裂纹稳态扩展区,裂纹以条带循环机制向前扩展,同时能看到许多疲劳条纹。

The bars of TC21 alloy with a diameter of 90mm were produced by α＋β and β processing. Under the same conditions, fatigue crack growth rate of bars produced by two different processing technics were investigated. Fatigue crack growth rate with fine and coarse lamellar structure were characterized. The results showed that material structure influenced the magnitude of crack propagation, microstructure with fine lamellar structure produced by β processing technic had a lower fatigue crack growth rate compared with the coarse lamellar structure produced by α＋β processing technic, with the increasing of lamellar thickness, fatigue crack growth rate accelerated. In the stationary state growth region, fatigue crack grew ahead in the form of striation mechanism, many fatigue striations were observed by scanning electronic microscopy at the meantime.