Conference Publications

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Browsing Conference Publications by browse.metadata.impactarea "Advanced Casting Technologies"

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    Dynamic deformation behavior of the TM380 mild steel subjected to blast
    (2025-06) Shoke, Lerato S; Sono, Tleyane J; Mutombo, Kalenda; Snyman, IM
    The dynamic deformation behavior of the mild-steel TM380 subjected to explosive loading has been investigated. An imparted impulse and high pressure, from a PE4 explosive charge, interacted with the plate which is attached to a deflection gauge designed to measure the mid-point deflection time history and the imparted impulse. The shape of the bulge at the midsection of the plate was that of a paraboloid. The deflection-time curve is characterized by an escalation, followed by a very short plateau of a few microseconds at mid-point deflection, and finally a drop in deflection timespan. The dynamic strain, strain rate and impulse changes are revealed by deflection-time, velocity-time and hydrostatic pressure curves. Although no significant change in grain size and morphology occurs after shock wave loading, the pearlite lamellar structure transformed into spheroidized cementite as a result of shock induced phase transformation.
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    Effect of milling speed on the formation of Ti-6Al-4V via mechanical alloying
    (2018-10) Daswa, Pfarelo; Gxowa, Zizo; Monareng, Mathibe JI; Mutombo, Kalenda
    Ti-6Al-4V alloys are well known for good corrosion resistance, excellent surface oxide biocompatibility and high specific strength. This paper investigates the influence of milling parameters on the formation of Ti-6Al-4V alloy processed using mechanical alloying. A mixture of CP Ti and master alloy (60Al-40V) powder were milled using a high energy ball mill (HEBM) in order to produce a mechanically alloyed Ti-6Al-4V alloy powder. Milling was carried out at a constant milling time of 5 hours at varying speeds of 800, 900, 1000 and 1100 rpm in order to investigate the influence of speed on the formation of Ti-6Al-4V alloy. Scanning electron microscopy with energy dispersive analysis (EDX) and X-ray diffraction (XRD) were performed on the mechanically alloyed powder to investigate the chemical homogeneity and the formation of alpha (a) and beta (ß) phase during the mechanical alloying of CP Ti and 60Al- 40V.
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    Impact of post weld heat treatment on structural and mechanical properties of dissimilar high strength steels
    (2026-02) Shoke, Lerato S; Mutombo, Kalenda; Olubambi, P; Zondi, MC
    This study explores the influence of Submerged Arc Welding (SAW) parameters on the microstructural evolution, mechanical properties, and residual stresses in dissimilar welds of A516 Gr70 and A106 GrB high-strength carbon steels. Through a comprehensive experimental approach, this study delineates the direct relationship between the welding heat input, determined by the voltage, current, and speed, and its profound impact on the heat-affected zone (HAZ) size, microstructure, and mechanical properties, such as hardness and tensile strength. The investigation revealed that the optimal welding parameters play a critical role in controlling the bead geometry and HAZ size, which in tum significantly affect the mechanical integrity and performance of the welded joint. Notably, this study revealed that a higher heat input does not necessarily lead to a larger HAZ, challenging the conventional assumptions in welding practices. Furthermore, this study delves into the effects of post-weld heat treatment (PWHT) techniques, including normalizing, quenching, and annealing, on reversing the microstructural alterations induced by welding and restoring the initial mechanical properties of the base metals. Microstructural analyses employing stereo microscopy, optical microscopy, scanning electron microscopy, and X-ray diffraction techniques provide insight into the granular details of the morphological changes across different regions of the weld, highlighting the formation of martensitic lathes in the weld bead region and variations in the pearlite-ferrite matrix. Mechanical testing and hardness profiles substantiate these findings, illustrating the significant influence of cooling rates and heat treatment methods on the mechanical properties of the weldments. This study highlights the importance of controlled heat treatment in enhancing material performance, suggesting avenues for further research into parameter optimization, fatigue assessments, and advanced heat treatment techniques to refine welding processes for industrial applications.