Metallic additive manufacturing: State-of-the-art, process-structure-property relationships, and emerging trends

The Metal Additive Manufacturing (AM) has become a revolutionary manufacturing paradigm which facilitates the production of complex, lightweight and high-performance parts which are more design flexible compared to the traditional subtractive manufacturing. The review discusses the leading metal 3D printing technologies and they include Selective Laser Melting (SLM), Direct Metal Laser Sintering (DMLS), Electron Beam Melting (EBM), Directed Energy Deposition (DED), and Binder Jetting. The experiment examines how the feedstock properties, especially powder morphology and wire based materials affect the process stability and quality of the part. Moreover, the most important process parameters, including laser power, scanning speed, and thermal conditions are addressed in connection with microstructure development, defect formation and residual stresses. Mechanical performance such as tensile strength, hardness, fatigue resistance, and anisotropy are measured and methods of post-processing are measured through heat treatment, hot isostatic pressing, and surface finishing. The review also shows new industrial uses and explains the existing issues in terms of cost, reproducibility, certification, and sustainability, as well as describes the future research opportunities in multi-material printing, in-situ monitoring, and AI-based optimization of processes.