时效处理对不同热轧Ti-3.5Al-5Mo-4V钛合金组织与性能的影响

Effect of aging treatment on microstructure and mechanical properties of different hot-rolled Ti-3.5Al-5Mo-4V titanium alloy

采用光学显微镜(OM)、扫描电镜(SEM)、万能试验机和显微硬度计等研究了不同温度时效对热轧后Ti-3.5Al-5Mo-4V钛合金组织及力学性能的影响。结果表明:合金在单相区热轧过程表现出较高的相稳定性,热轧后组织由单一的β相组成,并且热轧过程中发生动态再结晶,而经双相区热轧后,合金的组织由初生α相(α_(p))和β相组成。在随后时效热处理过程,随着时效温度的升高,α_(p)相和析出的次生α相(α_(s))逐渐粗化,并且α_(s)相的含量逐渐减少,导致合金的强度降低、塑性升高。双相区热轧后合金在520℃时效6 h后获得较好的强塑性匹配:抗拉强度为1436.5 MPa,伸长率为9.4%。

Effect of aging at different temperatures on microstructure and mechanical properties of hot rolled Ti-3.5Al-5Mo-4V titanium alloy were studied by means of optical microscope(OM),scanning electron microscopy(SEM),universal testing machine and microhardness tester.The results show that the alloy shows high phase stability during hot rolling in single-phase zone,and after hot rolling,the microstructure of the alloy is singleβphase,dynamic recrystallization occurs during hot rolling.While after hot rolling in dual-phase zone,the microstructure of the alloy is composed of primaryαphase(α_(p))andβphase.During the subsequent aging heat treatment,with the increase of aging temperature,α_(p) phase and secondary precipitationαphase(α_(s))gradually coarsened,and the content of α_(s) phase decreases gradually,which leads to the decrease of strength and the increase of plasticity of the alloy.After hot rolling in the dual phase zone,the alloy has a good strength plasticity matching after aging at 520℃for 6 h:the tensile strength is 1436.5 MPa and the elongation is 9.4%.