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Ti-6Al-4V合金具有强度高、抗蚀性优异、生物相容性好等优点,常用于制造医用多孔的植入体材料,但对多孔材料结构的成型工艺有一定的约束。基于选区激光熔化成型技术(Selective Laser Melting,SLM),结合自行设计的拓扑优化多孔网格结构,按照拓扑优化的结果重新建模成单元结构,进行了3组特殊结构(螺旋结构、拱形桥结构、薄壁件与小孔)的制造实验,并且分析对比了热处理前后SLM制造的Ti-6Al-4V合金的显微组织和拉伸性能。研究结果表明,SLM成型的三种螺旋结构中,除30°螺旋结构以外,其他两种都能够完整成形,满足拓扑单元结构成形角度(≥45°)的制造,30°螺旋结构通过在迎向刮刀锐角面下加少量支撑也能成形;拱形桥实验中,能够完整成型不发生塌陷的最大拱桥尺寸为φ=8mm,推导出最大的可悬垂长度为0.70mm,满足拓扑单元结构最大拱桥尺寸(8mm)要求;壁厚为0.10mm的薄壁结构由于激光光斑尺寸的约束,成形尺寸增大了0.05mm,可能会造成1mm边长尺寸成单元拓扑结构孔隙率的减小;小孔实验成形最小孔径为0.10mm,满足多孔拓扑优化结构最小孔制作要求;SLM制造直接态和热处理态Ti-6Al-4V合金试样基本的力学性能均能达到ISO制定力学性能标准,且超过铸造态的水平,但延展性能仍不及锻件。热处理态比直接态的延展性好,直接态组织为针状的α′相马氏体组织;当热处理温度达到750℃时,α′相会开始发生扩散分解,从而在相界面析出白色的β相小颗粒。
Ti-6Al-4V alloy with high strength, excellent corrosion resistance, good biocompatibility, etc., commonly used in the manufacture of porous medical implant material, but the porous material structure of the molding process has some constraints. Based on the SLM (Selective Laser Melting) technology and the self-designed topology-optimized porous mesh structure, the cell structures were re-modeled according to the topology optimization results. Three sets of special structures (spiral structure, arch bridge Structure, thin-walled parts and small holes) manufacturing experiments, and analysis and comparison of heat treatment before and after the SLM Ti-6Al-4V alloy produced by the microstructure and tensile properties. The results show that the three kinds of helical structures formed by SLM can be completely formed except the 30 ° helical structure, which can satisfy the forming angle (≥45 °) of topological unit structure. In the arched bridge experiment, the maximum arch size that can be completely formed without collapsing is φ = 8 mm, and the maximum suspendable length is 0.70 mm, which meets the maximum arch size of topological unit structure (8mm) requirements; wall thickness of 0.10mm thin-walled structure due to the laser spot size constraints, the forming size increased by 0.05mm, may result in 1mm edge length into the cell topology of the porosity decreases; The minimum hole diameter is 0.10mm, which meets the requirements of the smallest holes in the porous topological optimization structure. The basic mechanical properties of the as-received and heat treated Ti-6Al-4V alloy fabricated by SLM can meet the ISO mechanical properties and exceed the casting state , But the ductility is still less than forgings. The heat treatment state is better than the direct state ductility, and the direct state is acicular α ’phase martensite. When the heat treatment temperature reaches 750 ℃, the α’ phase will start to diffuse and decompose, thus precipitating white β Small particles.