东北大学学报（自然科学版）

东北大学学报:自然科学版 ›› 2017, Vol. 38 ›› Issue (3): 345-349.DOI: 10.12068/j.issn.1005-3026.2017.03.009

• 材料与冶金 • 上一篇    下一篇

显微组织对近α钛合金BT-20疲劳裂纹扩展的影响

郭庆清1， 王佳亮2， 吴永红3， 姜永正4   

  1. (1. 中南大学 地球科学与信息物理学院， 湖南 长沙410083； 2. 湖南科技大学 海洋矿产资源探采装备与技术湖南省工程实验室， 湖南 湘潭411201; 3. 通号轨道车辆有限公司， 湖南 长沙410100; 4. 湖南科技大学 湖南省机械设备健康维护重点实验室， 湖南 湘潭411201)
  • 收稿日期:2015-10-16 修回日期:2015-10-16 出版日期:2017-03-15 发布日期:2017-03-24
  • 通讯作者: 郭庆清
  • 作者简介:郭庆清( 1967－)，男，江西泰和人，中南大学博士研究生.
  • 基金资助:
    国家自然科学基金资助项目(51271203).

Influence of Microstructure on the Fatigue Crack Growth in Near-α Ti Alloy BT-20

GUO Qing-qing1， WANG Jia-liang2， WU Yong-hong3， JIANG Yong-zheng4   

  1. 1. School of Geosciences and Info-physics， Central South University， Changsha 410083， China； 2. Hunan Provincial Key Laboratory of Equipment and Technology for Oceanic Mineral Resource， Hunan University of Science and Technology， Xiangtan 411201， China； 3. CRSC Railway Vehicles Co.， Ltd.， Changsha 410100， China; 4. Hunan Provincial Key Laboratory of Health Maintenance for Mechanical Equipment， Hunan University of Science and Technology， Xiangtan 411201， China.
  • Received:2015-10-16 Revised:2015-10-16 Online:2017-03-15 Published:2017-03-24
  • Contact: JIANG Yong-zheng
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摘要： 通过显微镜及电子背散射衍射试验对近α钛合金BT-20的篮网、双态和魏氏组织微观结构及晶粒尺寸进行测定，并采用拉伸与疲劳裂纹扩展试验进行力学性能以及裂纹扩展研究，讨论微观组织对裂纹扩展速率、路径和断口形貌的影响.结果表明，双态组织的强度和延伸率最好，魏氏组织最差；双态组织的断口为解理断裂，裂纹碰到大尺寸初生α晶粒时发生穿晶失效，形态呈直线状，从而具有较高的扩展速率；篮网和魏氏组织的断口形式为沿相界断裂，裂纹扩展路径在通过α晶粒集束边界时改变方向，路径呈曲线状，扩展速率相对较低，从而具有较好的耐裂纹性能.

关键词: BT-20, 近α钛合金, 疲劳裂纹扩展, 显微组织, 断口形貌

Abstract: The lamellar， bimodal， acicular microstructures and grain morphology of BT-20 near-α Ti alloy were observed by optical microscopy and electron backscatter diffraction. Tensile and fatigue crack growth tests were carried out to analyze the mechanical property and the influence of microstructures on fatigue crack growth rate， path and fractography. The results showed that the bimodal microstructure has the highest strength and best ductility， and acicular microstructure exhibits the lowest strength and poor ductility. The fractography of bimodal microstructure is cleavage fracture. The transgranular fracture happens when crack encounters the large primary α grain， which results in a relatively straight profile of the crack and explains the higher crack growth rate. The fractography of the lamellar and acicular microstructures is intergranular fracture. The crack path changes direction when encounters boundaries of two colonies of α grains， which results in tortuosity of the crack， lower crack growth rate and a better crack growth resistance.

Key words: BT-20, near-α Ti alloy, fatigue crack growth, microstructure, fractography

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