准β热处理工艺对TC4-DT钛合金组织和拉伸性能的影响

Effect of quasi-beta heat treatment on microstructure and tensile properties of TC4-DT titanium alloy

摘要:

研究了不同准β热处理工艺对TC4-DT钛合金显微组织和力学性能的影响，并对显微组织、力学性能断口形貌进行了对比分析。结果表明随着固溶温度从Tβ+10℃升高到Tβ+25℃，合金初生片状α相长宽比变大，次生α相含量升高，塑性下降，抗拉强度升高。冷却速率的下降对于初生片状α相有粗化效果，降低初生片状α相的长宽比，对应的抗拉强度升高，塑性降低。固溶时间的延长，初生片状α相宽度变大，长宽比下降，次生片状α相长宽比变大。TC4-DT钛合金拉伸断口存在大小不一的韧窝，随固溶温度的升高和时效时间的延长，试样拉伸断口韧窝的尺寸均有不同程度的变大，同时出现了少量的撕裂棱，试样的断裂机制为以韧性断裂为主并伴有准解理断裂。

Abstract:

The effect of different quasi-beta heat treatment processes on the microstructure and mechanical properties of TC4-DT titanium alloy were investigated, and the microstructure and mechanical properties fracture morphology were compared and analyzed. The results show that with the increase of solution temperature from Tβ+10℃ to Tβ+25℃, the ratio of length to width of primary α phase and the content of secondary α phase increased, the plasticity decreased and the tensile strength increased. The decrease of cooling rate has coarsened effect on the primary lamellar α phase, which reduce the aspect ratio of the primary lamellar α phase, Therefore the tensile strength gradually increased, while the plasticity gradually decreased. With the prolongation of solution time, the width of the primary lamellar α phase increases and the aspect ratio decreased, while the aspect ratio of the secondary lamellar α phase increased.There are many dimples with different size on the fracture of TC4-DT alloy. With the increase of solution temperature and the extension of aging time, the size of dimples of tensile fracture samples increased to varying degrees, and a small number of tearing edges appeared at the same time. The fracture mechanism of the samples is mainly ductile fracture with quasi-cleavage fracture.