激光选区熔化近α钛合金开裂机理及抑制研究

摘要

The cracking mechanism and inhibiting process were discussed through studying the crack morphology,propagation direction and crack source of a new near αphase titanium alloy speci-men fabricated by SLM using scanning electron microscopy and so on.The experimental results show that:uneven notches arose from the sidewall of the specimen during fabricationas well as Ti3 O,TiO, TiC which are hard and brittle.Under the actions of residual stress,the cracks originate in the sidewall notches and expand in the deposition along these hard and brittle compounds.When the laser power is 140 W,scanning speed is 450 mm/s,layer thickness is 0.03 mm,scanning space is 0.07 mm,preheating temperature is 350 ℃ during SLM and preserve 1 h,slow cooling to room temperature,the number of cracks reduce significantly.%研究了近α钛合金激光选区熔化(SLM)成形开裂机理及抑制工艺,利用扫描电子显微镜等研究了试件裂纹形貌及其扩展方向、裂纹源等问题。研究结果表明：SLM 成形过程中在试样侧壁形成凹凸不平的缺口及 Ti3 O、TiO、TiC 等硬脆化合物；在残余应力作用下,裂纹起源于侧壁缺口,在沉积层上沿硬脆化合物扩展。当工艺参数为激光功率140 W,扫描速度450 mm/s,铺粉层厚0.03 mm,扫描间距0.07 mm,SLM 成形温度350℃,保温1 h 缓冷至室温时,可有效抑制试件开裂。