Investigation of microstructure, tensile and fatigue properties of 3D printed alloys

• Main Author: Yip, Cheng Yu
• Other Authors: Upadrasta Ramamurty
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/172892
• Institution: Nanyang Technological University

Additive Manufacturing (AM) is a manufacturing process that fabricates physical objects from three-dimensional (3D) Computer-Aided Design (CAD) models. Unlike traditional subtractive manufacturing, AM builds objects from bottom up, adding materials layer-by-layer, allowing intricate geometries to be manufactured. AM has emerged as a transformative technology today with profound implications for the fabrication of metallic components, with a wide range of applications across various industries. It has evolved tremendously to allow metal alloys to be printed through various processes. 316L stainless steel is very ductile, biocompatible, and resistant to corrosion. It has been demonstrated by numerous investigations that processing 316L stainless steel using Directed Energy Deposition (DED) is feasible. 316L stainless steel's material qualities can be enhanced by forming Metal Matrix Composites (MMCs) out of reinforcing particles like TiB2. In this report, TiB2 reinforced 316L Stainless Steel was manufactured using DED to undergo microstructure study, fatigue, and tensile tests to understand its properties. Extensive microstructural investigation showed severe cracking at the dendritic boundaries. Tensile test results showed much lower strength and ductility as compared to conventionally manufactured counterparts due to the presence of such cracks. Subsequently, the high cycle fatigue response also suffered with a reduction of fatigue limit by ~20%.