Development of residual stress measurements on additive manufactured parts

• Main Author: Wu, Shaun Junjie
• Other Authors: David Lee Butler
• Format: Final Year Project
• Language: English
• Published: 2016
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/68801
• Institution: Nanyang Technological University

The usage of additive manufacturing (AM) for Rapid Prototyping and Rapid Manufacturing is a growing and emerging market, which is gradually gaining popularity. Major companies in various industries such as biomedical, automotive and aerospace are adopting this process. Although, AM has advantages over conventional manufacturing, there are still hurdles present for it to become widely accepted. Challenges such as poor surface finishing, porosity and even residual stresses. Selective Laser Melting (SLM) is a powder bed fusion system that binds metallic powder through melting, layer by layer to form a three dimensional component. This process, however, introduces residual stress into the component via the thermal gradient mechanism (TGM). Center Hole Drilling (CHD) method has been widely and commonly used for measurement of residual stress. The aim of this study is to understand the trend of the development of residual stress on components with different thickness and heat treatment post processing. From the study, thinner test coupons residual stress readings were generally unstable as compared to the thicker test coupons. Heat treatment stress relieving effects were different for the thinner and thicker test coupons. Lastly, base plate removal was found to have helped relieve some residual stresses as well.