Metal additive manufacturing (AM) refers to any process of making 3D metal parts layer-upon-layer via the interaction between a heating source and feeding material from a digital design model. The rapid heating and cooling attributes inherent to such an AM process result in heterogeneous microstructures and the accumulation of internal stresses. Post-processing heat treatment is often needed to modify the microstructure and/or alleviate residual stresses to achieve properties comparable or superior to those of the conventionally manufactured (CM) counterparts. However, the optimal heat treatment conditions remain to be defined for the majority of AM alloys and are becoming another topical issue of AM research due to its industrial importance. Existing heat treatment standards for CM metals and alloys are not specifically designed for AM parts and may differ in many cases depending on the initial microstructures and desired properties for specific applications. The purpose of this paper is to critically review current knowledge and discuss the influence of post-AM heat treatment on microstructure, mechanical properties, and corrosion behavior of the major categories of AM metals including steel, Ni-based superalloys, Al alloys, Ti alloys, and high entropy alloys. This review clarifies significant differences between heat treating AM metals and their CM counterparts. The major sources of differences include microstructural heterogeneity, internal defects, and residual stresses. Understanding the influence of such differences will benefit industry by achieving AM metals with consistent and superior balanced performance compared to as-built AM and CM metals.

金属增材制造 (AM) 是指通过热源与数字设计模型中的进料之间的相互作用，逐层制造 3D 金属部件的任何过程。这种增材制造工艺固有的快速加热和冷却属性会导致不均匀的微观结构和内应力的积累。通常需要后处理热处理来改变微观结构和/或减轻残余应力，以实现与传统制造 (CM) 对应物相当或更优的性能。然而，大多数增材制造合金的最佳热处理条件仍有待确定，并且由于其工业重要性而成为增材制造研究的另一个热门话题。CM 金属和合金的现有热处理标准并不是专门为 AM 零件设计的，并且在许多情况下可能会有所不同，具体取决于特定应用的初始微观结构和所需性能。本文的目的是批判性地回顾当前的知识，并讨论增材制造后热处理对主要类别增材制造金属（包括钢、镍基高温合金、铝合金、钛合金）的微观结构、机械性能和腐蚀行为的影响和高熵合金。该评论阐明了热处理 AM 金属与其 CM 对应物之间的显着差异。差异的主要来源包括微观结构异质性、内部缺陷和残余应力。