(1. 西安建筑科技大学 冶金工程学院，西安 710055；
2. 云南钛业股份有限公司，楚雄 651209；
3. 昆明理工大学 材料科学与工程学院，昆明 650093)
摘 要: 本文研究了轧制火次对电子束冷床(EB)熔炼TC4钛合金显微组织、织构和力学性能的影响。结果表明：随着轧制火次的增加，原始铸态试样中粗大晶粒被破碎，晶粒逐渐等轴化，形成大量细小的等轴α相，小角度晶界(LAGBs)逐渐增加；相比于一火次轧制变形，三火次轧制变形后LAGBs提高35.1%，位错密度逐渐增加。轧制过程中钛合金β→α转变发生了变体选择。一火次轧制后形成T型织构，柱面<a>滑移优先开动，随着轧制火次的增加，织构类型发生转变。三火次轧制后，试样的抗拉强度和塑性显著提高，与铸态试样相比，RD与TD方向室温与400 ℃抗拉强度分别增加271 MPa、189 MPa和300 MPa、402 MPa，断后伸长率分别增加7.4%、15.3%和7.6%、4%。RD与TD方向室温断裂机制分别从准解理断裂和脆性断裂逐渐转变为微孔聚集型断裂。
关键字: TC4钛合金；电子束冷床熔炼；显微组织；微观织构；力学性能
（1. School of Metallurgical Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, China;
2. Yunnan Titanium Industry Co., Ltd., Chuxiong 651209, China;
3. School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China）
Abstract:The influence of the hot rolling process on the microstructure, microtexture and mechanical properties of Ti-6Al-4V alloy fabricated by electron beam cold hearth melting were investigated. The results show that the prior coarse grains are broken with the increase of the heating deforming number. The grains gradually change to the equiax to form a mass of fine equiaxed α phases. Besides, the fractions of the Low Angles Grain Boundaries (LAGBs) increase with the heating deforming number. After the third heating deforming, the fractions of LAGBs increases by 35.1%, compared with the fractions of LAGBs after the first heating deforming. Meanwhile, the dislocation density increases. The variant selection occurring during the β → α transformation during the hot rolling process. The strong “T” textures are found after the first heating deforming, and the prismatic 〈a〉 slip system triggers firstly. The texture component changes with the increase of the heating deforming number. The tensile strength and elongation of the samples significantly improve after the third heating deforming. The tensile strength of the sample at room temperature and 400 ℃ increase by 271 MPa and 189 MPa in the rolling direction and 300 MPa and 402 MPa in transverse direction, respectively, compared with the as-cast sample. In addition, the elongation of the sample at room temperature and 400 ℃ increase by 7.4% and 15.3% in rolling direction and 7.6% and 4% in transverse direction, respectively. The fracture mechanisms change from quasi-cleavage fracture to ductile fracture in rolling direction, and the fracture mechanisms change from brittle fracture to ductile fracture in transverse direction.
Key words: TC4 titanium alloy; electron beam cold hearth melting; microstructure; microtexture; mechanical property
