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Olawale S. Fatoba

Bio: Olawale S. Fatoba is an academic researcher from University of Johannesburg. The author has contributed to research in topics: Microstructure & Titanium alloy. The author has an hindex of 11, co-authored 67 publications receiving 356 citations. Previous affiliations of Olawale S. Fatoba include Vaughn College of Aeronautics and Technology.

Papers published on a yearly basis

Papers
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Journal ArticleDOI
TL;DR: In this paper , the optimization of the multi-performance characteristics of MIG welded butt joint of AISI 1008 mild steel and stainless steel by hybrid Grey-based Taguchi method was studied.
Abstract: Welding processes play a significant role in many fabrication and manufacturing industries. Among various welding processes that have been developed over the years, Gas Metal Arc Welding (GMAW) or Metal Inert Gas Welding (MIG) has received a lot of interest due to its ability to weld a variety of metallic materials, easy adaptation for automation, high deposition rate, high efficiency, and low capital requirement. This study focus on the optimization of the multi-performance characteristics of MIG welded butt joint of AISI 1008 mild steel and AISI 316 austenitic stainless steel by hybrid Grey based Taguchi method. L9 Taguchi orthogonal array was adopted for the optimization of the MIG welding current, voltage and gas flow rate. The weld joint integrity has been assessed in terms of the tensile strength, yield strength, percentage elongation and Vickers microhardness of the fusion zone. Welding current of 180 A, voltage of 14 V, and gas flow rate of 19 l/min were obtained as the optimal parameter setting for the MIG welding process. The tensile strength, yield strength, percentage elongation and hardness of 559.25 MPa, 382.22 MPa, 33.34%, and 250.63 HV respectively were obtained at the optimal setting. Voltage was the most significant process parameter with 63.76% contribution for the multi-performance of the weldments. The confirmatory test was performed to validate the optimization process which proved Grey based Taguchi method to be an easy but yet effective method for multi-performance characteristics optimization of welded joints.

5 citations

Book ChapterDOI
01 Jan 2019
TL;DR: In this paper, the microstructure and elemental and phase composition of Ti-Al-Cu coating on Ti-6Al-4V Alloy were studied. And the microhardness testing results indicated that the fabricated coatings had enhanced by 61.9% as compared to the micro-hardness of the Ti-10Al-9Cu alloy substrate.
Abstract: Laser metal deposition technique was used for the fabrication of Ti–Al–Cu coating on Ti–6Al–4V Alloy. The microstructure and elemental and phase composition of coatings were studied. The SEM images showed the homogeneous distribution of Cu addition in Ti–10Al–9Cu at scanning speed of 1.0 m/min. Strong metallurgical bond without pores and cracks were observed between the coating and the substrate. Grain refinement was observed within the microstructure as the grains grew in a columnar and dendritic pattern in a counter direction to heat flow. However, the cross-section microstructures of Ti–10Al–6Cu and Ti–10Al–3Cu at 0.8 and 1.0 m/min scanning speed and laser power of 1000 and 1100 W showed minute pores and cracks. The existence of amorphous phase revealed via XRD was also observed in the coatings. The microstructure of these alloys is highly influenced by processes involving plastic deformation and thermal treatments which, in effect, determines the mechanical properties adhering to desired properties. The microhardness testing results indicated that the fabricated coatings had enhanced by 61.9% as compared to the micro-hardness of the Ti–6Al–4V alloy substrate.

5 citations

Journal ArticleDOI
TL;DR: In this paper, the influence of temperature distribution and thermal stresses on the laser additive manufactured Titanium alloy grade 5 was investigated using 3000 W continuous wave Ytterbium Laser System (YLS).

4 citations

Journal ArticleDOI
TL;DR: In this article, the authors used commercially pure Titanium and SiAlON powders at varied composition (98%Ti/2%SiAlON and 95% Ti/5%SiO2) to fabricate composite coating on Ti6Al4V substrate by laser cladding at altered scanning speed (0.6 and 1.2 m/min).

4 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, a comprehensive review of the laser cladding (LC) material system is presented, as high entropy alloys (HEAs), amorphous alloy and single crystal alloy have been gradually showing their advantages over traditional metal materials in LC.
Abstract: In industries such as aerospace, petrochemistry and automobile, many parts of different machines are under environment which shows high temperature and high pressure, and have their proneness to wear and corrosion. Therefore, the wear resistibility and stability under high temperature need to be further improved. Nowadays, Laser cladding (LC) is widely used in machine parts repairing and functional coating due to its advantages such as lower dilution rate, small heat-affected zone and good metallurgical bonding between coating and substrate. In this paper, LC is introduced in detail from aspects of process simulation, monitoring and parameter optimization. At the same time, the paper gives a comprehensive review over LC material system as high entropy alloys (HEAs), amorphous alloy and single crystal alloy have been gradually showing their advantages over traditional metal materials in LC. In addition, the applications of LC in functional coatings and in maintenance of machine parts are also outlined. Also, the existing problems and the development trend of LC is discussed then.

245 citations

Journal ArticleDOI
11 Jun 2019
TL;DR: In this paper, a review of the relationship between the unique microstructures and the corresponding corrosion behavior of several metallic alloys fabricated by selective laser melting is presented, including Ti-based, Al-based and Fe-based alloys.
Abstract: Additive manufacturing is an emerging technology that challenges traditional manufacturing methods. However, the corrosion behaviour of additively manufactured parts must be considered if additive techniques are to find widespread application. In this paper, we review relationships between the unique microstructures and the corresponding corrosion behaviour of several metallic alloys fabricated by selective laser melting, one of the most popular powder-bed additive technologies for metals and alloys. Common issues related to corrosion in selective laser melted parts, such as pores, molten pool boundaries, surface roughness and anisotropy, are discussed. Widely printed alloys, including Ti-based, Al-based and Fe-based alloys, are selected to illustrate these relationships, and the corrosion properties of alloys produced by selective laser melting are summarised and compared to their conventionally processed counterparts.

140 citations

01 Jan 2003
TL;DR: In this paper, the effects of pulse energy, pulse frequency, powder mass flow rate and spot overlap on the clad layer height, dilution and heat-affected zone (HAZ) have been examined.
Abstract: A systematic research into the cladding of stellite 6 on stainless steel by pulsed Nd:YAG laser has been carried out. The effects of pulse energy, pulse frequency, powder mass flow rate and spot overlap on the clad layer height, dilution and heat-affected zone (HAZ) have been examined. It was found that both the clad height and penetration into the substrate increase with the pulse energy, spot overlap and pulse frequency, but the effects of these parameters on dilution are complex. The dilution reaches the lowest value (4%) at the incident energy of 18 and 25 J/ pulse, spot overlap of 89% and pulse frequency of 40 Hz. The powder mass flow rate of 22 g/min (for energy of 25 J/pulse and spot overlap of 83%) produces thick clad layer with low dilution but results in the formation of defects. The hardness of the clad layer decreases linearly with increasing dilution. No cracks have been found in single-track clad layers at a spot overlap of 89%, however, cracks occurred at lower spot overlap. These cracks were eliminated by the multi-track cladding when the track increment is less than 1/3 of the width of track, which is believed to be due to the remelting or heat treatment of the previous clad track by the subsequent track. The track bands in multi-track clad show coarser structure, higher element segregation and lower hardness.

136 citations

Journal ArticleDOI
TL;DR: In this article, a joint powder-fed laser metal deposition (LMD) system with two independent powder delivery systems was used to fabricate Inconel 718 alloys with different TiC contents.

54 citations

Journal ArticleDOI
TL;DR: In this article, a 3kW continuous wave ytterbium laser system (YLS) was used to fabricate the coatings, and to control the movement of the cladding process, a KUKA robot was attached to the system.
Abstract: The marine, aerospace, and power machinery industries show progression in the application of titanium alloy components due to their good properties. However, the alloy exhibits poor thermal stability, low hardness, and poor tribological properties; as a result, the use of Ti6Al4V in various industries is restricted. Consequently, a search for surface improvement of Ti6Al4V alloy arose with the intention of enhancing its endurance. The use of laser metal deposition method by integrating chemical barrier coatings is considered as advantageous; therefore, an investigation aimed at surface improvement of Ti6Al4V by incorporation of Ti-Co coatings developed. To fabricate the coatings, a 3-kW continuous wave ytterbium laser system (YLS) was used, and to control the movement of the cladding process, a KUKA robot was attached to the system. The microstructure, corrosion, and mechanical properties of the titanium alloy-cladded surfaces were studied at different laser process parameters. To analyze the microstructure of the cross section, optical and scanning electron microscopy were employed. A laser power of 750 W and scanning rate of 1.2 m/min were found to be the optimum process conditions for a 60Ti-40Co alloy. When comparing the mechanical properties of the alloy and bare substrate, the alloy exhibited a significant increase in terms of the hardness. It was found to have 719 HV as compared to 301 HV which is that of the substrate, this indicates to an increase of 58.14% in the hardness. Lower laser scanning rates result in a larger fraction of hard-intermetallic phases which in turn lead to coatings with enhanced hardness levels. Furthermore, the yield strength and tensile strength of the coatings increased to maxima of 2.30 and1.66 GPa, respectively in comparison to the substrate, due to the addition of Co. Additionally, the corrosion rates of all the coated specimens were reduced as a result of the oxide films formed on the laser-coated Ti6Al4V alloy samples.

50 citations