Mechanical Properties of Solid and Porous Ti6Al4V Fabricated by EBM

• Main Authors: Wen-Xiang Lin, 林文翔
• Other Authors: 陳貞光
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/vta692

碩士 === 國立臺北科技大學 === 材料科學與工程研究所 === 106 === Additive manufacturing is a promising process, which can customize build complex freedom structure by selective melting of metal powders. The electron beam melting (EBM) is one of additive manufacturing processes suitable for metal products of high melting point. The printing process is kept in vacuum environment to avoid oxidation of metal powders. Electron beam also preheats powder layer before printing, so hard and brittle phases generated due to high temperature gradient can be effectively reduced. In this study, both solid and porous Ti-6Al-4V specimens manufactured by EBM were investigated. As-built solid parts show that their ultimate tensile strength, yield strength and elongation are 1022 MPa, 995 MPa, 9.4% for horizontal specimens, 912 MPa, 888 MPa, 8.3% for vertical specimens, respectively. Because of the EBM process characteristics that the powder bed can maintain high temperature throughout the entire printing process, so that the α’ acicular structure formed by the rapid cooling of Ti-6Al-4V alloy is decomposed into fine α+ß lamellar structure. All solid parts of Ti-6Al-4V manufactured by EBM comply with ASTM’s specification of Ti-6Al-4V castings for surgical implants. Meanwhile, the tetradecahedron cellular structures manufactured by EBM show greater variation in strut quality. The cellular EBM parts with 64% porosity demonstrates similar fatigue strength to that of human cortical bones after one million cyclic stress.