The residual stress (RS) in laser powder bed fusion (LPBF) IN718 alloy samples produced using a 67°-rotation scan strategy is investigated via laboratory X-ray diffraction (XRD) and neutron diffraction (ND). The location dependence of the strain-free (d₀) lattice spacing in ND is evaluated using a grid array of coupons extracted from the far-edge of the investigated specimen. No compositional spatial variation is observed in the grid array. The calculated RS fields show considerable non-uniformity, significant stress gradients in the region from 0.6 to 2 mm below the surface, as well as subsurface maxima that cannot be accounted for via XRD. It is concluded that failure to determine such maxima would hamper a quantitative determination of RS fields by means of the stress balance method.

中文翻译：

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激光粉末床融合 IN718 中亚表面残余应力的重要性

通过实验室 X 射线衍射 (XRD) 和中子衍射 (ND) 研究了使用 67° 旋转扫描策略生产的激光粉末床熔合 (LPBF) IN718 合金样品中的残余应力 (RS)。ND 中无应变 ( d ₀ ) 晶格间距的位置依赖性使用从研究样本的远边缘提取的试样网格阵列进行评估。在网格阵列中没有观察到成分空间变化。计算得到的 RS 场在地表以下 0.6 至 2 mm 的区域中显示出相当大的不均匀性、显着的应力梯度，以及无法通过 XRD 解释的地下最大值。得出的结论是，无法确定这样的最大值将妨碍通过应力平衡方法对 RS 场进行定量确定。