选区激光熔化TC4小裂纹扩展特性数值模拟

发展了一种考虑微观组织的选区激光熔化（SLM）钛合金TC4小裂纹扩展数值模拟方法。基于SLM TC4的微观组织观测结果，利用Voronoi算法并通过晶体取向筛选，实现了微观组织建模。在此基础上，采用扩展有限元法建立了SLM TC4材料小裂纹扩展行为模拟方法，探究沉积方向以及晶粒尺寸、晶体取向等微观组织对小裂纹扩展速率的影响规律。结果表明:沉积方向影响材料的裂纹扩展抗力，沉积方向与裂纹扩展方向平行时，材料抵抗疲劳小裂纹扩展的性能相对更好。晶粒尺寸影响小裂纹扩展速率，晶粒尺寸越大，小裂纹扩展速率越快。晶体取向影响速率的波动性，不同晶体取向材料的小裂纹扩展速率上下界有明显差异。 

Numerical simulation of small crack growth in selective laser melting TC4

A numerical simulation method of small crack growth in selective laser melting （SLM） titanium alloy TC4 considering microstructure was developed.Based on the microstructure observation results of SLM TC4，the microstructure modeling was realized by Voronoi diagram and crystallographic orientation screening.The extended finite element method was used to establish the simulation method for small crack growth behavior of SLM TC4 to explore the influences of buildup direction，grain size，crystallographic orientation and other microstructure on the small crack growth rate.The buildup direction affected the crack growth resistance，and the material had better resistance to fatigue small crack growth when the buildup direction was parallel to the crack growth direction.The grain size affected the small crack growth rate，the growth rate of small crack became faster with the increase of grain size.The crystallographic orientation affected the volatility of the crack growth rate，the upper and lower bounds of small crack growth rate of materials with different crystallographic orientations were obviously different.