Chapter 3 - Selective laser melting: principles and surface quality

Abstract

Selective laser melting (SLM) is one of the most widely used additive manufacturing (AM) processes for metallic materials, based on powder-bed fusion. It can be defined as a process whereby 3D functional parts can be produced by selectively scanning and consolidating a powder bed in a layer-wise manner. SLM provides many advantages over conventional processes such as ability to create complex geometries with internal cavities or features without specific dies or tools, reduced lead time from design to testing, reduced need for assemblies, and joining processes resulting in less production costs. However, there are some shortcomings of the SLM process, which are inherent to layered manufacturing like other AM technologies. The main shortcomings of the process are the questionable quality of produced specimens in terms of mechanical properties, production rates, dimensional accuracy leading to need for postfinishing operations and surface quality issues. The surface quality is an important engineering aspect of produced parts since it has a significant effect on the performance and durability of parts. Many part properties such as wear characteristics, corrosion, fatigue depend on the surface quality. Thus, the manufacturing defects in the SLM process causing problems related to surface integrity and quality are subject of this chapter. After the SLM process is introduced by explaining its physical background and process parameters as well as material issues, the research on surface integrity of the SLM process is reviewed. Next, the treatments for the surface enhancement applied after the SLM process and the obtained results are summarized. Future trends regarding surface problems of this process are given as final remarks.