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主要讨论了TC4-DT钛合金不同片层结构的疲劳裂纹扩展速率。试验通过几种不同的热处理工艺获得不同的片层组织结构参数,深入研究了片层组织结构参数对疲劳裂纹扩展速率的影响规律,并对裂纹扩展断口进行分析。结果表明:双重处理空冷条件获得细片层组织较炉冷条件获得粗片层组织具有较高的疲劳裂纹扩展阻力;多重热处理由于获得的次生α片层,导致不同阶段裂纹扩展机理与双重处理的不同。在相同的第一重处理条件下,多重处理在中速扩展区的裂纹扩展速率较双重处理的高。由于次生α片层组织具有较好的变形协调性,加快裂纹的扩展,因此具有较双重空冷处理较高的疲劳裂纹扩展速率。
The fatigue crack growth rates of different sheet structures of TC4-DT titanium alloy are mainly discussed. Several different heat treatment processes were used to obtain different structural parameters of the lamellar structure. The influence of the lamellar structure parameters on the fatigue crack propagation rate was studied in depth and the crack propagation fracture was analyzed. The results show that the microstructure of fine lamellar layer obtained by the dual treatment of air cooling has higher fatigue crack propagation resistance than that of the cold lamellar layer. The multiple α-lamellae obtained by multiple heat treatment lead to the crack growth mechanism and the double treatment s difference. Under the same first processing condition, the crack growth rate of multi-treatment in medium-speed extension zone is higher than that of double treatment. As the secondary α-lamellar structure has good deformation coordination, to speed up the expansion of the crack, so has a higher than double air-cooled fatigue crack growth rate.