Effect of Inter-Layer Time Interval on the Mechanical Behavior of Direct Laser Deposited Ti-6Al-4V

Due to its wide applicability in the biomedical and aerospace fields, where unique and/or difficult to machine geometries are required, Ti-6Al-4V continues to be a strong candidate for additive manufacturing. In this study, the effect of inter-layer time interval on the mechanical behavior of Ti-6Al-4V fabricated via Laser Engineered Net Shaping (LENSTM) is investigated. Two sets of specimens were fabricated, each with their own inter-layer time interval, accomplished by depositing either one or two specimens per operation. Tensile tests and fully reversed, strain controlled fatigue tests were conducted on the specimens. Experimental results indicate that specimens fabricated using longer inter-layer time intervals possess a higher ultimate tensile strength, lower ductility, and finer microstructure relative to those fabricated using shorter time intervals. Additionally, specimens fabricated using longer inter-layer time intervals possessed shorter fatigue lives due to presence of more process defects, such as pores and lack of fusion, inherent to additive manufacturing. Such effects are important to consider when producing multi-part assemblies or large parts.