Laser additive manufacturing of metallic components: materials, processes and mechanisms

TLDR

Additive manufacturing builds parts layer‑by‑layer from powder using lasers, enabling complex metallic components for aerospace, defense, automotive and biomedical applications, with laser sintering, melting and deposition as the most versatile processes. This review seeks to clarify how material characteristics and processing conditions influence metallurgical mechanisms, microstructure and mechanical properties, and to establish a relationship between material, process and metallurgical outcomes in laser‑based AM. It defines laser sintering, melting and deposition processes, discusses powder categories and densification mechanisms, and examines the physical, microstructural and mechanical aspects that govern the performance of laser‑additive‑manufactured metallic components.

Abstract

Unlike conventional materials removal methods, additive manufacturing (AM) is based on a novel materials incremental manufacturing philosophy. Additive manufacturing implies layer by layer shaping and consolidation of powder feedstock to arbitrary configurations, normally using a computer controlled laser. The current development focus of AM is to produce complex shaped functional metallic components, including metals, alloys and metal matrix composites (MMCs), to meet demanding requirements from aerospace, defence, automotive and biomedical industries. Laser sintering (LS), laser melting (LM) and laser metal deposition (LMD) are presently regarded as the three most versatile AM processes. Laser based AM processes generally have a complex non-equilibrium physical and chemical metallurgical nature, which is material and process dependent. The influence of material characteristics and processing conditions on metallurgical mechanisms and resultant microstructural and mechanical properties of AM processed components needs to be clarified. The present review initially defines LS/LM/LMD processes and operative consolidation mechanisms for metallic components. Powder materials used for AM, in the categories of pure metal powder, prealloyed powder and multicomponent metals/alloys/MMCs powder, and associated densification mechanisms during AM are addressed. An in depth review is then presented of material and process aspects of AM, including physical aspects of materials for AM and microstructural and mechanical properties of AM processed components. The overall objective is to establish a relationship between material, process, and metallurgical mechanism for laser based AM of metallic components.