The influence of the process gas, laser scan speed, and sample thickness on the build-up of residual stresses and porosity in Ti-6Al-4V produced by laser powder bed fusion was studied. Pure argon and helium, as well as a mixture of those (30% helium), were employed to establish process atmospheres with a low residual oxygen content of 100 ppm O₂. The results highlight that the subsurface residual stresses measured by X-ray diffraction were significantly lower in the thin samples (220 MPa) than in the cuboid samples (645 MPa). This difference was attributed to the shorter laser vector length, resulting in heat accumulation and thus in-situ stress relief. The addition of helium to the process gas did not introduce additional subsurface residual stresses in the simple geometries, even for the increased scanning speed. Finally, larger deflection was found in the cantilever built under helium (after removal from the baseplate), than in those produced under argon and an argon-helium mixture. This result demonstrates that complex designs involving large scanned areas could be subjected to higher residual stress when manufactured under helium due to the gas’s high thermal conductivity, heat capacity, and thermal diffusivity.

研究了工艺气体、激光扫描速度和样品厚度对激光粉末床熔合产生的 Ti-6Al-4V 残余应力和孔隙率的影响。使用纯氩气和氦气以及它们的混合物（30% 氦气）来建立残留氧含量低至 100 ppm O _{2 的}工艺气氛. 结果表明，通过 X 射线衍射测量的亚表面残余应力在薄样品 (220 MPa) 中显着低于长方体样品 (645 MPa)。这种差异归因于较短的激光矢量长度，导致热量积聚，从而导致原位应力消除。向工艺气体中添加氦气不会在简单的几何形状中引入额外的表面下残余应力，即使扫描速度有所提高。最后，在氦气下建造的悬臂（从基板上移除后）发现了比在氩气和氩氦混合物下生产的悬臂更大的挠度。这一结果表明，由于气体的高热导率，在氦气下制造时，涉及大扫描区域的复杂设计可能会受到更高的残余应力，