Experimental investigation on the strength and stiffness of 3D printed stainless steel S/S-316L parts

• Main Author: Muhammad Syahimi Bin Salim
• Other Authors: Seah Leong Keey
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Mechanical engineering::Mechanics and dynamics
• Online Access: https://hdl.handle.net/10356/167135
• Institution: Nanyang Technological University

Additive manufacturing (AM) is a method of producing an object layer by layer. It is the reverse of the machining process which involves removing small amounts of a solid material block at a time until it is the finished product. Additive manufacturing metal such as stainless steel has been an ongoing trend for the past years, but there are limitations to additive manufacturing such as the fatigue strength. This study aims to evaluate the strength and stiffness of 3D printed metal by comparing the properties between 3D printed and conventional manufactured stainless steel using various mechanical testing to provide as an alternative material in the engineering industry. In this project, 12 specimens (three Tensile subsize, eight Fatigue) were fabricated under the American Society for Testing Material (ASTM) standard. Direct Metal Laser Sintering (DMLS) was the chosen additive manufacturing technology. The specimens undergone Non-Destructive Testing (NDT) such as Ultrasonic and Scanning Electron Microscopy (SEM) to check for defects and understand the microstructure of the specimen. Followed by Hardness, Tensile and Fatigue tests to obtain the findings and understanding its mechanical properties. The findings of the mechanical properties were recorded to analyse deeper on the strengths and weakness of DMLS technology. It will be compared with Conventional Manufactured (CM) method and other additive manufacturing technologies used. In terms of comparing with CM specimens, the DMLS specimens have higher Hardness value, Ultimate Tensile Strength (UTS) but lower Young’s Modulus and fatigue life cycle. Whereas comparing the DMLS specimens with other AM technologies such as Direct Energy Deposition (DED) and Selective Laser Melting (SLM), the DMLS specimens’ hardness value can be considered the best among the AM technologies. DMLS specimens’ UTS value is found to be better than DED specimens. DMLS specimens’ fatigue life cycles can be considered similar with the other AM technologies.