热处理工艺对高强钛合金组织及力学性能的影响

Effect of Heat Treatment on Microstructure and Mechanical Properties of High Strength Titanium Alloy

近β高强钛合金广泛应用于航空航天领域,通过显微组织调控获得良好的强韧性匹配是高强钛合金的研究重点。以一种新型近β钛合金为研究对象,通过调控热处理制度获得不同β晶粒尺寸及不同晶界形貌的组织,分别研究了β晶粒尺寸随固溶时间的变化规律、两阶段固溶过程晶界的粗化行为以及晶粒尺寸及晶界形貌对合金力学性能的影响。结果表明:β相区固溶时间延长导致β晶粒尺寸增加,但对合金拉伸及冲击性能没有显著影响;两阶段固溶中α+β相区固溶时初生α相优先沿晶界析出并长大,使晶界粗化,α+β相区固溶温度越低晶界粗化效果越明显;晶界粗化同时降低合金的强度与塑性,但对冲击韧性没有显著影响。

The near β high-strength titanium alloy is widely used in the aerospace field.Microstructure control is being focused on to achieve a good match between strength and toughness of high-strength titanium alloys.The size of β grains and the morphology of grain boundaries of a novel near β titanium with different heat treatments were characterized in this paper.The grain size was affected by the solution time,and the behavior of grain boundary coarsening was affected by(α+β)phase region solution.The effect of grain size and the morphology of grain boundary on mechanical properties were studied.The results show that the β grains grow up gradually with the extension of solution time inβphase region,and the size of β grains has no significant effect on tensile property and impact toughness.In the process of two-stage solution,the primaryαphase precipitates preferentially along the grain boundary,which coarsen the grain boundary.The lower temperature in the(α+β)phase region solution,the more obvious the grain boundary coarsening.The grain boundary coarsening reduces the strength and plasticity of at the same time,but has no significant effect on the impact toughness.