Selective laser melting of 316L stainless steel/ TiB2 metal matrix composite

• Main Author: Ng, Yek Khee
• Other Authors: Zhou Wei
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2020
• Subjects: Engineering::Mechanical engineering; Engineering::Manufacturing; Engineering::Materials
• Online Access: https://hdl.handle.net/10356/140983
• Institution: Nanyang Technological University

Selective Laser Melting (SLM) is one of the popular Additive Manufacturing (AM) techniques used owing to its ability to create fully dense parts with good mechanical properties. SLM, like most AM techniques, uses a layer wise building process. A powder feedstock is first spread over a substrate layer before a laser melts selected regions of powder according to the CAD data provided. After the SLM process, the sample is prepared for analysis under an optical microscope. The sample preparation process can be narrowed down to the few steps of mounting, grinding, polishing, and etching. After these processes have been carried out, the microscopy reveals the underlying microstructure present on the sample. In this project, the analysis of SLM printed 316L stainless steel and 316L/TiB2 Metal Matrix Composite (MMC) were carried out. From the optical microscopy of both samples, it was observed that for the 316L stainless steel sample, melt pools with epitaxial columnar grains and cellular dendritic microstructure were observed. However, the 316L/TiB2 did not produce such results, instead melt pools had a dark inner zone surrounded by a brighter outer. Microhardness testing was carried out om 316L and 316L-1TiB2 MMC samples. It was found that the microhardness of 316L-1TiB2 was higher than pure 316L. The microhardness value of 316L-1TiB2 obtained was 340.7 HV while pure 316L was only 244.2 HV. Thus, the observations show that the addition of TiB2 into the 316L can increase the strength of the material.