激光选区熔化成形Ti6Al4V合金的热处理组织演变机理  

Heat Treatment Microstructural Evolution of Selective Laser Melting Ti6Al4V Alloy

作　　者：胡富国 柯林达 肖美立[2,3] 韩远飞 吕维洁[1] HU Fuguo;KE Linda;XIAO Meili;HAN Yuanfei;Lu Weijie(State Key Laboratory of Metal Matrix Composites,Shanghai Jiao Tong University,Shanghai 200240,China;Shanghai Engineering Technology Research Center of Near-Net-Shape Forming for Metallic Materials,Shanghai 201600,China;Shanghai Aerospace Precision Machinery Institute,Shanghai 201600,China)

机构地区：[1]上海交通大学金属基复合材料国家重点实验室,上海200240 [2]上海金属材料近净成形工程技术研究中心,上海201600 [3]上海航天精密机械研究所,上海201600

出　　处：《上海航天》2019年第2期96-103,共8页Aerospace Shanghai

基　　金：国家自然科学基金(U1602274;51501112;51875349;51741108;51701116);国家重点研发计划(2018YFB1106403);上海市科委基础研究项目(17JC1402600)

摘　　要：激光选区熔化(SLM)Ti6Al4V成形构件需要通过热处理改善其塑性。为探究该过程中的组织特征和演变机理,研究了Ti6Al4V试样固溶时效热处理(910℃/8 h水冷,750℃/4 h炉冷)前后的微观形貌和力学性能。结果表明:沉积态的马氏体α′相尺寸具有层次结构;热处理相变时初生马氏体α′发生分解,小尺寸马氏体α′转变为β相,随后发生β→(α+β)转变,最后得到α相片层和精细(α+β)相结构均匀分布的组织;热处理后材料抗拉强度达1 055 MPa,延伸率提升至16.2%,均优于典型Ti6Al4V合金拉伸性能。采取的热处理技术对Ti6Al4V组织调控成效显著,满足后续工艺要求,可在激光选区熔化成形双相钛合金中推广应用。Heat treatments need to be applied to selective laser melting (SLM) produced Ti6Al4V to achieve the superior ductility.In order to explore the microstructure and transformation mechanism of the process,the microstructure and tensile properties of Ti6Al4V samples are studied during heat-treatment of solution and aging (at 910 ℃/8 h water cooling,750 ℃/4 h furnace cooling).The results are as follows.Martensite α′ phase size has a hierarchical structure.In the process of heat treatment,primary martensite α′ is decomposed,small-sized martensite α′ is transformed into β phase,whereafter β phase is transformed into (α+β) during the aging.Finally,coarse lamellar α phases and ultrafine lamellar (α+β) phases are uniformly distributed in the microstructure.After the heat treatment,the ultimate tensile strength of the Ti6Al4V reaches 1 055 MPa,and the elongation increases to 16.2%,which are better than the tensile properties of the national standard Ti6Al4V alloy.The heat-treated Ti6Al4V material can meet the requirements of subsequent processes,which can be popularized in the selective laser melting of the two-phase titanium alloy.

关 键 词：TI6AL4V 增材制造 微观组织 马氏体相变 拉伸性能 

分 类 号：TN911.73[电子电信—通信与信息系统] TP391.9[电子电信—信息与通信工程]