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研究了Ti-6 Al-4 V合金的拉伸塑性(ψ)和显微组织对其断裂韧性(K_(lc))及裂纹扩展速率(da/dN)的影响。结果表明,魏氏组织合金的β原始晶粒度D_β与ψ呈反比关系。D_β<440μm,α片厚度b=-2.5～3.5μm时,K_(lc)最高。K_(lc)及da/dN与ψ的关系与组织类型有关,随ψ增大,K_(lc)升高,达到一定数值后,对于魏氏组织,K_(lc)不再变化,对于等轴组织,则K_(lc)下降。魏氏组织及等轴组织的da/dN-ψ关系曲线上均有极小值。与空冷退火相比,淬火时效能显著降低合金的da/dN。进行990℃,1h,W.O.+950℃,20h-A.C.处理,能获得最佳K_(lc)及da/dN。
The effects of tensile plasticity (ψ) and microstructure on fracture toughness (K_ (lc)) and crack growth rate (da / dN) of Ti-6Al-4V alloy were studied. The results show that the original grain size of β is inversely proportional to ψ. K_ (lc) is the highest when D_β <440μm and the thickness α is b = -2.5 ~ 3.5μm. The relationship between K_ (lc) and da / dN and ψ was related to the type of tissue. With the increase of ψ, the K_ (lc) increased. After reaching a certain value, the K_ (lc) Organization, K_ (lc) decline. The relationship between da / dN-ψ of Wei’s tissue and isometric tissue is the minimum. Compared with air-cooled annealing, quenching time significantly reduces the alloy da / dN. The best K_ (lc) and da / dN were obtained at 990 ℃, 1h, W.O. + 950 ℃, 20h-A.C.