电子束快速成形TC4合金的组织与断裂性能

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英文篇名：Microstructure and fracture property of electron beam rapidly manufactured TC4 alloy 作者：童邵辉 ; 李东 ; 邓增辉 ; 方虎 英文作者：TONG Shao-hui;LI Dong;DENG Zeng-hui;FANG Hu;The Engineering Training Center,Shanghai University of Engineering Science;School of Materials Engineering,Shanghai University of Engineering Science; 关键词：电子束选区熔化 ; 断裂性能 ; 各向异性 ; α相形态 ; 断口 英文关键词：electron beam selective melting;;fracture property;;anisotropy;;α phase morphology;;fracture 中文刊名：CLGC 英文刊名：Journal of Materials Engineering 机构：上海工程技术大学工程实训中心;上海工程技术大学材料工程学院; 出版日期：2019-01-11 11:00 出版单位：材料工程 年：2019 期：v.47;No.428 基金：国家自然科学基金项目(51405288) 语种：中文; 页：CLGC201901019 页数：6 CN：01 ISSN：11-1800/TB 分类号：129-134

摘要

利用超景深显微镜和扫描电镜对电子束选区熔化快速成形的沉积态TC4试样组织与断口形貌进行观察和分析,研究不同几何成形和加载方向对断裂性能的影响。结果表明,断裂性能在垂直试样中受到柱状晶组织的影响,具有各向异性,在沉积方向上的断裂韧度为94.94MPa·m~(1/2),大于电子束扫描方向的断裂韧度85.33MPa·m~(1/2),而伸长率很小,仅为3%;α相形态对断裂性能有影响:水平试样片层状的α集束组织伸长率及断裂韧度优于垂直试样相互交错的针状α组织,最大值为14.5%和101.45MPa·m~(1/2),而抗拉强度和屈服强度较小;电子束选区熔化制备的TC4试样断口由许多不同尺寸的韧窝和弯曲的撕裂棱组成,断裂方式以延性韧窝状沿晶断裂为主,水平试样的断口撕裂棱曲折程度、韧窝尺寸和深度大于垂直试样。
        Microstructure and fracture morphologies of as-deposited TC4 samples fabricated by rapid manufacture of electron beam selective melting(EBSM) were observed and analyzed by a digital microscope and a scanning electron microscope respectively. The influence of different build geometries and load directions on the fracture properties was studied. The results indicate that fracture properties of vertical samples are influenced by columnar crystals and characterized by its anisotropy. The fracture toughness(K_(IC)) in the deposition direction of vertical samples is 94.94 MPa·m~(1/2), which is greater than that in the electron beam scanning direction(85.33 MPa·m~(1/2)), and the elongation(δ) of 3% is very low; α morphology has some influence on the fracture properties. The elongation(δ) and fracture toughness(K_(IC)) in horizontal samples with lamellar α colony are greater than that in vertical samples with crossed acicular α, and the maximum is 14.5% and 101.45 MPa·m~(1/2), while the ultimate tensile strength(σ_b) and the yield strength(σ_(0.2)) are lower; furthermore, the fracture of EBSM-TC4 samples consists of different sizes of dimples and circuitous tearing ridges. So the fracture method is characterized by ductile dimple-based intergranular fracture and the circuitous degree of tearing ridges as well as size and depth of dimples on the fracture morphologies of horizontal samples are greater than that in vertical samples.

引文

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