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对具有片层α相的Ti-17合金圆饼在两相区进行5种变形程度的等温锻造及固溶时效处理,用定量金相学方法研究了片层α相在热加工过程中的演变规律。研究发现:α相的厚度随着应变量的增大而增大;变形程度及圆饼的变形区域对α相形态的变化有很大影响。随变形程度的增大,α相的形态参数FeretRatio(Feretmax/Feretmin)的分布曲线在FeretRatio介于1.5～2.5区间出现单峰,且峰值不断增大,大FeretRatio的α相比例逐渐减小。圆饼中心位置的FeretRatio分布曲线具有较大的峰值。大变形使片层α相的等轴化程度提高,改善了圆饼的组织均匀性。等效应变对组织中不同形态α相分布的影响曲线表明:球化α相比例随着等效应变的增大呈单调增大,增大速率表现为慢—快—极慢的分阶段特征;近等轴状的α相比例先快速增长后不断减少;片层状和大片层状α相比例随着等效应变增大呈单调减少。片层α相的临界球化与完全球化的等效应变分别约为0.4与1.0。
Five stages of isothermal forging and solution aging treatment of Ti-17 alloy round cake with lamellar α phase were carried out in two-phase region. The evolution of lamellar α phase in hot working process was studied by quantitative metallography. The results show that the thickness of α phase increases with the amount of strain increasing, and the degree of deformation and the deformation area of cakes have a great influence on the change of α phase morphology. With the increase of deformation degree, the distribution curve of the shape parameter of the α-phase FeretRatio (Feretmax / Feretmin) appears single peak in the FeretRatio range of 1.5 ~ 2.5, and the peak value increases continuously, and the proportion of α phase of the large FeretRatio decreases gradually. The FeretRatio distribution curve at the center of the round cake has a larger peak. The large deformation increases the degree of equiaxedisation of the alpha phase of the sheet and improves the texture homogeneity of the cakes. The curves of the effect of equivalent strain on the distribution of different phase α phases in the microstructure show that the proportion of spheroidized α phase monotonically increases with the increase of equivalent strain, and the increase rate shows slow-fast-extremely slow phases. The proportion of nearly equiaxial α phase decreased rapidly at first and then decreased rapidly. The proportion of lamellar and lamellar α phase decreased monotonically with the increase of equivalent strain. The critical spheroidization and complete spheroidization of α-phase lamellae are about 0.4 and 1.0 respectively.