Manufacturing functionally graded materials using selective laser melting

• Main Author: Nur Hafiza Mohd Zulkifli.
• Other Authors: Leong Kah Fai
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Manufacturing::CAD/CAM systems; DRNTU::Engineering::Mechanical engineering::Prototyping
• Online Access: http://hdl.handle.net/10356/54192
• Institution: Nanyang Technological University

Selective laser melting (SLM) is a powder-based additive manufacturing technique which produces parts layer-by-layer from a 3-dimensional computer-aided design (CAD) model. Today, there is an emerging interest to apply this technology for creating objects with high geometrical complexity. In order to introduce SLM process into industry for manufacturing functional components, desired mechanical properties of final product, such as high tensile strength, must be attained. Hence, it is essential to understand and predict the microstructure of the final product produced by SLM so as to perfect the use of SLM in the various industries. Advanced material such as alloy Ti-6Al-4V produced by SLM is being studied. The focus is on the microstructure of the material and its grain growth characteristics following the SLM process. The focus is to have a greater understanding of the alloy and contribute to the deeper study of the material. The primary objective of the project is to understand the grain growth of Ti-6Al-4V, before developing a model that relates the direction of the laser beam and the solidification front. In addition, the model is intended to create a visual representation on the effect on the grain growth direction when the scanning velocity is varied. Preliminary work of this project includes carrying out literature review pertaining to the SLM of Ti-6Al-4V. This covers an array of aspects of SLM, such as how varying process parameters of SLM affect the material’s porosity and mechanical properties. However, the focus of the literature review was on works pertaining to the grain growth mechanism. More specifically, to observe and learn how scanning strategies affect the grain growth. Subsequently, the project was focused on the modeling of the grain growth mechanism under the SLM process. This includes the identification of an equation used in electron beam welding as a reference for the grain growth mechanism under SLM, followed by an evaluation of the breakdown of the identified equation. The phenomenon of the solidification in the SLM process will be focused on and being discussed intensively by making use of this proposed model if possible. MATLAB is used to create a graphical user interface (GUI) which acts as a platform for users to understand the microstructure better. With this modeling, it hopes to aid users in comprehending in the microstructure and grain growth and how it affects the mechanical property of a product. With this understanding, this model will be useful to fabricate desired product of specific mechanical property in order to assist in the fabrication of FGM.