Akademik Veri Yönetim Sistemi
Tez Türü: Doktora
Tezin Yürütüldüğü Kurum: University of Sheffield, School of Mechanical, Aeropace and Civil Engineering, Mechanical Engineering, İngiltere
Tez Danışmanı: Professor Kamran Mumtaz
Tezin Onay Tarihi: 2025
Tezin Dili: İngilizce
Desteklendiği Program: Diğer
Özet:
Additive manufacturing has revolutionised the production of complex, high-performance components, with Laser Powder Bed Fusion (LPBF) and Electron Beam Melting (EBM) leading the way. These technologies enable precise layer-by-layer fabrication using metallic powders, offering reduced material waste and unprecedented design freedom. Despite these advantages, challenges such as microstructural heterogeneity, residual stresses, and defects persist, particularly in Ti6Al4V alloy components. LPBF often induces martensitic microstructures due to rapid cooling rates, compromising ductility, while EBM, although better at reducing residual stresses, struggles with achieving fine microstructural control.
Diode Point Melting (DPM) represents a novel approach in additive manufacturing, utilising eight pieces of 5.5W (the maximum power can be taken from single 450 nm emitter) diode lasers focusing on a single focal point, offering a more affordable and accessible alternative to conventional. This method offers significant advantages over traditional Laser Powder Bed Fusion (LPBF) systems, including improved energy efficiency, reduced equipment costs, and enhanced scalability. By integrating DPM with targeted laser heating, this work seeks to address key challenges in AM, such as thermal gradients and microstructural customisation. This research also investigates the innovative integration of Dynamic Laser Assisted Heating (DLAH), and Diode Point Melting (DPM) to overcome these challenges. The hybrid system synergises preheating strategies with precision melting, addressing critical limitations of LPBF and EBM. Comprehensive experimental studies were conducted to optimise laser parameters and preheating conditions, while advanced characterisation techniques, including electron backscatter diffraction (EBSD) and X-ray diffraction (XRD), were employed to analyse microstructural and mechanical outcomes.
The findings demonstrate that combining DLAH with DPM significantly alters the mechanical properties of Ti6Al4V components by refining microstructures, reducing defects, and mitigating the formation of martensite. This dual-laser approach promotes uniform thermal gradients, ensuring superior layer bonding and improved dimensional accuracy. The results also highlight the potential for scalability and industrial adoption, making this method a promising advancement in the field of additive manufacturing.