(1. 西安建筑科技大學 冶金工程學院，西安 710055；
2. 云南鈦業(yè)股份有限公司，楚雄 651209；
3. 昆明理工大學 材料科學與工程學院，昆明 650093)
摘 要: 本文研究了軋制火次對電子束冷床(EB)熔煉TC4鈦合金顯微組織、織構和力學性能的影響。結果表明：隨著軋制火次的增加，原始鑄態(tài)試樣中粗大晶粒被破碎，晶粒逐漸等軸化，形成大量細小的等軸α相，小角度晶界(LAGBs)逐漸增加；相比于一火次軋制變形，三火次軋制變形后LAGBs提高35.1%，位錯密度逐漸增加。軋制過程中鈦合金β→α轉變發(fā)生了變體選擇。一火次軋制后形成T型織構，柱面<a>滑移優(yōu)先開動，隨著軋制火次的增加，織構類型發(fā)生轉變。三火次軋制后，試樣的抗拉強度和塑性顯著提高，與鑄態(tài)試樣相比，RD與TD方向室溫與400 ℃抗拉強度分別增加271 MPa、189 MPa和300 MPa、402 MPa，斷后伸長率分別增加7.4%、15.3%和7.6%、4%。RD與TD方向室溫斷裂機制分別從準解理斷裂和脆性斷裂逐漸轉變?yōu)槲⒖拙奂蛿嗔选?/span>
關鍵字: TC4鈦合金；電子束冷床熔煉；顯微組織；微觀織構；力學性能
（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
