Effect of scanning pattern and volumetric energy density on the properties of selective laser melting Ti-6Al-4V specimens

Abstract

Selective laser melting (SLM) is a potential additive manufacturing method for fabricating Ti-6Al-4V parts; however, the shortage of practical knowledge about the effect of volumetric energy density (VED) and scan pattern on the quality and defect formation of SLMed Ti-6Al-4V parts limited its use. In this paper, attempts are made to address the effect of some of the key process parameters on the location and type of defects, mass density, and hardness of the Ti-6Al-4V specimens manufactured via the SLM process. It was found that selecting proper VED cannot fully guarantee to reach a high-density part (>99%), and both scan pattern and VED must be considered as a combination for fabricating a high-density product. Moreover, the results of this study showed that the scan pattern plays a vital role in the defect type and its location. Thus, to produce a quality part, the selected scan pattern must be in accordance with the applied VED. The hardness of the specimens was evaluated and related to the applied scan pattern and resulting mass density. The hardness of high-density specimens at side surfaces were near to that of the wrought material, while at the top surfaces the hardness could be 10% higher than the wrought Ti-6Al-4V material.

Keywords

• Additive manufacturing
• Selective laser melting
• Ti-6Al-4V
• Defect formation
• Hardness measurement