Ti-6Al-4V合金的轧制与组织性能

采用光学显微镜、透射电镜和拉伸试验等手段,研究了多道次两向轧制和单向轧制对不同原始状态(热轧态、水淬态和空冷态)Ti-6Al-4V合金显微组织和力学性能的影响。结果表明,热轧态Ti-6Al-4V合金的组织为片状α相+β相+少量等轴α相,水淬态Ti-6Al-4V合金形成了针状马氏体组织,空冷态Ti-6Al-4V合金形成了网状组织。Ti-6Al-4V合金适宜的两向轧制温度为700 ℃,此时合金中可见颗粒状β相弥散分布在α基体上。两向轧制Ti-6Al-4V合金的抗拉强度和屈服强度从高至低顺序为:水淬态>热轧态>空冷态,且轧向强度要高于横向;相较于单向轧制,两向轧制明显降低了Ti-6Al-4V合金板材拉伸性能的各向异性,且水淬态Ti-6Al-4V合金的轧向和横向强度差异最小,700 ℃轧制Ti-6Al-4V合金的主要细化机制为位错细化。

Rolling,microstructure and properties of Ti-6Al-4V alloy

Effects of two-way rolling and one-way rolling on the microstructure and mechanical properties of Ti-6Al-4V alloys in different original states( hot-rolled,water-quenched and air-cooled) were studied by means of OM,TEM and tensile test. The results show that the microstructure of hot-rolled Ti-6Al-4V alloy is composed of flake-like α phase,β phase and a small amount of equiaxed α phase. The needle-like martensite is formed in water-quenched Ti-6Al-4V alloy and the net basket structure is formed in air-cooled Ti-6Al-4V alloy. The optimum two-way rolling temperature for Ti-6Al-4V alloy is 700 ℃,at which the granular β phase is dispersed on the matrix α. The order of tensile strength and yield strength of two-way rolling Ti-6Al-4V alloy from high to low is WQ > M > AC,and the strength in the rolling direction is higher than that in the transverse. Compared with unidirectional rolling,two-way rolling significantly reduces the anisotropy of tensile properties of Ti-6Al-4V alloy sheet,and the difference between the rolling and transverse strength of water-quenched Ti-6Al-4V alloy is the smallest,and the main refining mechanism of rolling Ti-6Al-4V alloy at 700 ℃ is the dislocation refine.