Additive manufacturing of Ti modified stainless steel

• Main Author: Lew, Yan Qi
• Other Authors: Zhou Wei
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/158936
• Institution: Nanyang Technological University

Additive manufacturing (AM) has reshaped the manufacturing industry by enabling the fabrication of complex parts. The industries benefited most from AM are aerospace, automotive and medical. Selective Laser Melting (SLM) is a commonly used AM method to fabricate metal components with good mechanical properties. A high-power density laser is used to melt the metal powder and fuse the metal layers into parts during SLM. The SLM fabricated samples are subsequently prepared for optical and scanning electron microscopy analyzation. The sample preparation steps consist of cutting, mounting, grinding, polishing, and etching process. This project analyse Ti modified stainless steel fabricated by SLM process with optimization parameter of laser power. The studies of microstructure of the following samples: 316L-0.3Ti, 316L-1Ti, 316L-1.5Ti, and 316L-3Ti, produced with a range of laser power from 150 W to 250 W were carried out. From the optical microscopy, defects and melt pool boundaries were observed. Ti segregation was also observed along the melt pool boundaries on all samples. Equiaxed grains and cellular structure were observed from the scanning electron microscopy. Microhardness test and tensile test was carried out to measure the mechanical properties of the sample. All the samples showed an improvement in hardness value and ultimate tensile strength compared to pure 316L, with 316L-1.5Ti obtaining 226.27 ± 29.34 HV and 817 ± 2 MPa respectively. Hence, the addition of Ti is concluded to strengthen 316L.