Fabrication of smart structures through selective laser melting (3D printing) (II)

• Main Author: Ong, Cindy
• Other Authors: Liu Yong
• Format: Final Year Project
• Language: English
• Published: 2016
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/68306
• Institution: Nanyang Technological University

The functional properties of shape memory alloys (SMAs) are highly dependent on the alloy’s microstructure, and hence any factor that affects its microstructure, such as its composition, must be carefully controlled to ensure optimal functionality of the alloy. Selective Laser Melting (SLM) of Nickel-Titanium SMAs uses high energy lasers to melt the powder, which in turn alters the microstructure of the alloy. Microstructure differs according to the SLM parameters used. As such, this study aims to determine the optimal laser power and scanning speed to be used for obtaining final parts that are dense and exhibit good shape memory properties. Samples will be manufactured using SLM with a range of laser powers and scanning speeds, and the number of samples narrowed down using visual dimensional analysis. Chosen samples have their densities measured using Archimedes method. Differential Scanning Calorimetric (DSC) is then used to determine the phase transformation temperatures of each sample. The sample with the largest deviation from Ni-Ti powder transformation temperatures will be subjected to X-ray Powder Diffraction (XRD) and Energy Dispersive X-ray Spectroscopy (EDS/EDX) to identify and quantify the cause of the temperature deviation. SLM parameters that produce the densest samples that have little deviation from powder temperatures are considered to be optimal parameters. This study also aims to investigate the effects of various scan patterns on sample densification. Samples will be fabricated with the previously determined optimal laser power and scan speeds with varying scan patterns. The samples will then undergo further functionality testings, as mentioned above, in order to conclude the optimal scan pattern for production of dense final parts.