Abstract Additive manufacturing technologies based on melting and solidification have considerable similarities with fusion-based welding technologies, either by electric arc or high-power beams. However, several concepts are being introduced in additive manufacturing which have been extensively used in multipass arc welding with filler material. Therefore, clarification of fundamental definitions is important to establish a common background between welding and additive manufacturing research communities. This paper aims to review these concepts, highlighting the distinctive characteristics of fusion welding that can be embraced by additive manufacturing, namely the nature of rapid thermal cycles associated to small size and localized heat sources, the non-equilibrium nature of rapid solidification and its effects on: internal defects formation, phase transformations, residual stresses and distortions. Concerning process optimization, distinct criteria are proposed based on geometric, energetic and thermal considerations, allowing to determine an upper bound limit for the optimum hatch distance during additive manufacturing. Finally, a unified equation to compute the energy density is proposed. This equation enables to compare works performed with distinct equipment and experimental conditions, covering the major process parameters: power, travel speed, heat source dimension, hatch distance, deposited layer thickness and material grain size.

中文翻译：

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重新审视基本焊接概念以改进增材制造：从理论到实践

摘要 基于熔化和凝固的增材制造技术与基于熔合的焊接技术具有相当大的相似性，无论是通过电弧还是高功率束。然而，在增材制造中引入了几个概念，这些概念已广泛用于填充材料的多道电弧焊。因此，基本定义的澄清对于在焊接和增材制造研究社区之间建立共同背景非常重要。本文旨在回顾这些概念，强调增材制造可以采用的熔焊的独特特征，即与小尺寸和局部热源相关的快速热循环的性质、快速凝固的非平衡性质及其影响上：内部缺陷的形成，相变、残余应力和变形。关于工艺优化，基于几何、能量和热考虑提出了不同的标准，允许在增材制造过程中确定最佳舱口距离的上限。最后，提出了计算能量密度的统一方程。该方程可以比较不同设备和实验条件下的工作，涵盖主要工艺参数：功率、行进速度、热源尺寸、孵化距离、沉积层厚度和材料粒度。允许在增材制造期间确定最佳舱口距离的上限。最后，提出了计算能量密度的统一方程。该方程可以比较不同设备和实验条件下的工作，涵盖主要工艺参数：功率、行进速度、热源尺寸、孵化距离、沉积层厚度和材料粒度。允许在增材制造期间确定最佳舱口距离的上限。最后，提出了计算能量密度的统一方程。该方程可以比较不同设备和实验条件下的工作，涵盖主要工艺参数：功率、行进速度、热源尺寸、孵化距离、沉积层厚度和材料粒度。