4. Understanding Metal for Additive Manufacturing

Additive manufacturing of metal exists at the convergence of a wide range of advanced technologies ranging from the design of computer solid models and computer-driven machines to high-energy beam processing of materials. Many technologists with diverse backgrounds are being drawn into additive manufacturing with little knowledge of or experience working with metals. This chapter provides a quick refresher of the building blocks of metal, its crystal or microstructure and the properties resulting from the chemistry of the specific metal alloy and the process used to form it into useful shapes. Simple examples are used to illustrate the wider range of forms and structures metal can take as a result of operations such as casting and rolling, then compared with metal processed by additive manufacturing methods. The non-metallurgist is introduced to less common forms of metal such as metal powders, wire, and electrodes as well as the microstructures formed by sintering and solidification. Less common materials such as composites, intermetallic, and metallic glasses are introduced as the potential use and application of these advanced materials is increasing as made possible by the adoption of additive manufacturing.