Showing papers by "Olawale S. Fatoba published in 2019"

Microstructural, mechanical and corrosion properties of aluminium MIG welds reinforced with copper powder

Abstract: Metal matrix composites have been used in recent times to achieve better mechanical properties of materials and welded structures. Aluminium and its alloys provide unique properties which makes it one of the most attractive metallic, economical, versatile material for a broad range of uses in engineering applications, such as aerospace, automobile and mineral processing industries. Against this background, aluminium is not suitable for all engineering applications, and it sometimes requires some degree of reinforcement, particularly in a corrosive environment and/or at elevated temperatures. This study focuses on ascertaining the integrity of MIG welded AA1100 reinforced with copper powder at the weld zone. This was achieved through tensile testing, microhardness profiling and microstructural investigation via the scanning electron microscope, the energy-dispersive spectroscopy and optical microscope, followed by corrosion test by electrochemical polarization method. The results revealed that the addition of copper powder significantly increased the hardness property of the welds, as the welds with copper powder particle reinforcement showed higher hardness values when compared to those without the copper powder particle reinforcement. The highest tensile strength was obtained from the copper reinforced sample. Furhermore, the microstructures revealed finer grain structures for the reinforced samples. The samples with reinforcement also exhibited better corrosion properties. It was therefore concluded that the aluminium (Al) and copper (Cu) metal matrix composite welded via MIG welding produced better mechanical properties, as well as increased corrosion resistance behaviour, and it can definitely be recommended for typical applications.

Effect of punch force on the upsetting deformation process using three-dimensional finite element analysis

Abstract: Forging is one of the conventional shaping technologies that is widely used for the manufacture of quality products for various industrial applications. The process involves the mechanical application of a punching force to deform a material to the desired shape and improved properties. In most cases, the manufacture of quality products depends on the experience of the designer and trial and error method thus making the process wasteful and costly. The present study reports on the application of finite element method (FEM) for the analysis of the effect of punch force on the stress/strain distribution during the deformation process as a step towards the reduction of trial and error methods in practice. The results show that increase in the punch force leads to inhomogeneity in the strain/stress distribution due to change in the deformation temperature resulting from the internal heat generated during plastic deformation stage and the frictional force at the punch-workpiece interface. It is also observed that the maximum effective strain occurs at the center of the deformed sample and the maximum effective stress occurs at the low effective strain regions. Moreover, the friction parameter increases as the punch force increases.

Numerical Modelling and Influence of Cu Addition on the Microstructure and Mechanical Properties of Additive Manufactured Ti–Al–Cu/Ti–6Al–4V Composite

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.

Titanium and Epoxy for Automobile application: A Review

Abstract: The transportation industry is no doubt a fast- growing sector of the economy of most countries. As the world population grows, there is a corresponding increase in the demand for an improved and functional transportation system. However, manufacturers and researchers in the automobile industry face a lot of challenges in order to meet up with the ever- increasing vehicle demand and government regulations. These challenges include the need to develop a motor vehicle that would be safe, economical and functional with low emission. Several strategies towards the development of advanced materials have been adopted to meet up with these challenges such as the replacement of heavy metallic parts with high strength and lightweight composite materials; and the use of nanoparticles as additives in fuel, tyre, lubricants, coatings and paints. Titanium as a material with low density, high rigidity, high corrosion resistance, good thermal stability, high strength, structural stability, and reflectivity together with epoxy resin which among other thermosetting and conventional thermoplastic polymers has improved mechanical, electrical, chemical and thermal properties, as well as low shrinkage, low cost and high compatibility with various reinforcing materials, have played significant roles in this regard. This review, therefore, examines the various applications of titanium and epoxy in the automobile industry. They have successfully been applied in the manufacture of lightweight parts, development of anti-fouling, anti-fogging, self-cleaning, corrosion resistant, flame retardant, hydrophilic and hydrophobic glasses, paints and coatings, efficient brake system and lubricants, improved engine performance, enhanced tyre and anti-microbial automobile interior components. This paper highlights the enormous applications of Titanium and epoxy in automobile.

The Effects of Silicon and Copper on the Microstructure and Wear Resistance Performance of Al-Si-Sn-Cu/Ti-6Al-4V Composite Coatings

Abstract: This research investigated the evolution of the final microstructural features and wear resistance property that commonly occur within the additive manufactured metal components that are complex to design from titanium alloys and are usually utilised for the various industry applications. The focus of the study encompassed the general knowledge of employing the most common range of additive manufacturing technologies in creating enhanced microstructure and mechanical properties of metal components fabricated by the additive manufacturing processes. This study investigated the characterisation of the performance of wear resistance of Titanium alloy Ti-6Al-4V cladded with Al-Si-Sn-Cu reinforcement which was fabricated by laser metal processing procedures Direct laser metal deposition (DLMD) is the broad manufacturing process characterised under metal additive manufacturing. The metallic substrate material was subjected to numerous processing parameters during fabrication of successive layering, namely the power of the laser beam, the environment in which the deposition took place, the temperature during processing and the rate in which the deposition took place. These important factors have significant influence on the final microstructure and wear resistance performance. CETR - MC reciprocating tribometer was used to analyse the different dadded samples produced by employing the method of direct laser metal deposition (DLMD). A continuous wave of 3 k W ytterbium laser system (YLS) laser was used for this experiment. It was quantified that the resulting wear resistance performance of the titanium alloy specimens produced was dominated by the manufacturing/processing method employed. The results obtained revealed that the wear characteristics of the cladded specimens fabricated by DLMD showed improved Coefficient of Friction (COF). The microstructural study conducted revealed that employing optimized parameters resulted in varied microstructures. Enhanced microstructure and tribological property were attained on account of sound optimized process parameters and suitable selection of reinforcement powders. The properties of the layers critically depend on the manufacturing/processing method and the optimized parameters. It was found that the main microstructural factors such as the porosity due to insufficient fusion, transformation of phases, morphology of the grains, the coarsening process of the microstructure, the heterogeneity in recrystallization and layer banding had a significant influence in the anisotropy and heterogeneity of the microstructure. The shielding phases lead to a decrease in COF and hence proved enhanced tribological property.

Effects of Silicon Carbide (SiC) Reinforcement on the Microstructure and Mechanical Properties of Laser Deposited Al-Sn-SiC/Ti-6Al-4V Composite Coatings

Abstract: Titanium and titanium alloys have a large array applications attributed to its low density, good corrosion resistance and high specific strength. Damage to the surface can be improved by surface modification for extended application. Direct laser metal deposition (DLMD) technique can be used to address the limitations associated with titanium alloy. This is mostly achieved by integration of reinforcement materials into the main matrix to form coating. Thereby inducing microstructural changes to the material. The morphology and also the hardness property of the various composite coatings were examined. The hardness of the composite coating was found to range between 450.64 and 638.22 HV, and the hardness obtained for 10% SiC reinforcement coating was 638.22 HV. For all the coatings, the hardness was established to be much higher than that of the substrate, which was averaged 304.21 HV. Hardness value increases with increase in SiC content. The enhanced hardness values were due to refined grains and intermetallics in the microstructure of the coatings. Moreover, the highest tensile and yield strengths was found at 10 wt.% SiC due to the uniform particle dispersion that can impede dislocation movement. The uniform distribution of SiC particles in the Al-Sn matrix had a good effect on its mechanical properties.

Numerical Modelling, Microstructural Evolution and Characterization of Laser Cladded Al-Sn-Si Coatings on Ti-6Al-4V Alloy

Abstract: In the quest of averting the drawbacks of alloys of titanium in advanced manufacturing, the laser metal deposition technique is used to fabricate suitable coatings with innovative microstructural evolution and unique surface properties in aggressive environment. The vital factor to be considered during direct laser metal deposition process is the simultaneous action of melting and fusion of the coating material to the base metal. The appropriate selection of laser processing parameter produced desirable result and properties. At scanning speed of 1.2 m/min, Al-10Sn-5Si coating has an ultimate hardness of 463.57 HV whilst at the scanning speed of 1.0 m/min the value has decreased to 398.36 HV (65.21 HV difference). Sample Al-10Sn-3Si also showed the same trend in increase hardness at 1.2 m/min. While Al-10Sn-1Si did not follow the trend of other two coatings. The model was developed to obtain insights on the behaviour of laser melted pools subjected to various process parameters. Simulation with 3D model with different values of various significant processing parameters such as laser power, scanning speed and powder feed rate influences the geometry and dynamics of the melt pool, and cooling rates.

The Effects of Manganese (Mn) Addition and Laser Parameters on the Microstructure and Surface Properties of Laser Deposited Aluminium Based Coatings

Abstract: Aluminium based alloy provides good combination of strength and corrosion resistance. They are light in weight, economically viable, amenable for production by various processing techniques and possess high strength. Aluminum and its alloys have been a successful metal material used for many applications like commodity roles, automotive and vital structural components in aircrafts. The present research was aimed at studying the effect of manganese (Mn) addition and laser parameters on the morphology and distribution of the iron-containing intermetallics in the Al-Si-Fe-Mn coatings. These Fe-intermetallic compounds influence the material properties during rapid cooling by laser deposition technique and play a crucial role for the material quality. Thus, the necessity of the effects of manganese addition on the surface properties of Al-Si-Fe-Mn alloy. A 3 kW continuous wave ytterbium laser system (YLS) attached to a KUKA robot which controls the movement of the alloying process was utilized for the fabrication of the coatings at optimum laser parameters. The fabricated coatings were investigated for its hardness performance. The field emission scanning electron microscope equipped with energy dispersive spectroscopy (SEM/EDS) were used to study the morphology of the fabricated coatings and X-ray diffractometer (XRD) for the identification of the phases present in the coatings. The refined microstructures and enhanced hardness performance were attributed to metastable intermetallic compounds, addition of manganese and optimized laser parameters.

Experimental Study of Hardness Property and Microstructure of TiZnNi Laser Deposited on Titanium Alloy

Abstract: The study is aimed at using laser cladding technique to deposit a thick coating of composite TiZnNi on titanium alloy Ti-6Al-4V substrate. The composite powder was mixed with Zinc (Zn), Nickel (Ni) and Titanium (Ti), in which the tubular mixer was used to prepare the mixture. The laser metal deposition technique that was employed in the process was used to control the heat input, which governed the resulting microstructure of the ZnNiTi coating that was produced. This was based on the analysis that was conducted. The results of the hardness obtained from the Vickers micro-indenter revealed that there was an improvement as the hardness measured for the cladded ZnNiTi layer was approximately 1396.90 HV 0. 1 and the hardness of the Ti-6Al-4V substrate was measured to be 320.8 HV 0. 1• This improvement was attributed to the NiTi, Ni3 Ti, hard Ni 4 Ti 3 and intermetallic phases that formed, this was confirmed by the analysis done on the cladded layer by employing EDS and XRD. The grain form and structure as well as the mechanical properties of the cladded layer were significantly affected by the heat input from the laser beam. At higher scanning speed of 1.0 m/min, the coating and substrate being limitedly mixed, resulted in the cladded layer having a significantly higher hardness than the substrate, but some hardness values gradually reduced after the cladded layer towards the interface and heat affected zone. The behaviour of the coating hardness property was improved by 4.4 compared to the hardness of the uncoated titanium substrate. The characteristics of the hardness of the deposited coating was heavily affected by processing parameters, which the grain morphologies and concentration of phase composition formed were predominant in the result of the hardness properties. Industries of biomedical and mechanical components may implement the application of composite ZnNiTi coating since there was an improvement on the hardness characteristics, which is usually of major concern in industrial applications.

Corrosion Inhibition of Martensitic Stainless Steel in Chloride Medium by Calcium Gluconate-Solanum Tuberosum Extract as Surfactant

Abstract: Corrosion inhibition of martensitic stainless steel (MSS) in magnesium chloride was investigated in the absence and presence of calcium gluconate as corrosion inhibitor at ambient temperature. The effects of inhibitor concentration were studied using weight loss and polarization method. The results obtained showed that calcium gluconate acts as an inhibitor for martensitic stainless steel in MgCl and decreases the corrosion rate. The inhibition performance was found to increase with the increase in inhibitor concentration. The maximum inhibition efficiency obtained was 99 % at 2g/v inhibitor concentration, the adsorption of calcium gluconate on the surface of Martensitic stainless steel was found to obey Langmuir adsorption isotherm. However, the addition of solanum tuberosum extract in the inhibitor decreases the corrosion rate of martesitic steel significantly in chloride solution.

Analysis of the Influence of Laser Parameters on the Microstructure and Surface Properties of Laser Deposited Aluminum Based Coatings

Abstract: The effects of processing parameters were investigated namely laser intensity and speed of laser scanning of Laser Metal Deposition (LMD) process had on the microstructure, metallurgical evolution, porosity generated in the coating, the geometrical property of the coating and the sizes of the grains in the coating. The processing parameters were applied in combinations in order to find the optimized settings of the process that least affects the metallurgical properties of the Ti-6Al-4V alloy substrate cladded with reinforced aluminium based powder. The temperature gradient and the rate of solidification of reinforcing the Ti-6Al-4V substrate with the aluminium based power were also focused on in terms of how they were influenced by the laser intensity and the scanning speed used in the building process. The inherent material properties were dependent on the process input parameters. The characterized performances considered in the investigation was influenced significantly by the laser processing intensity. The results of the investigation showed that the density had increased in proportion to the increase of the processing laser power coupled with the reduction of the speed of the laser scan. Moreover, for a laser power equivalent to and exceeding 950 W, the density became less susceptible to the laser power. The increased temperature field led to changes in geometry of the coatings as a results of more absorbed laser energy. The materials properties were influenced by the Fe-intermetallic compounds. The molten pool had columnar grains which were fully developed, along its volume as determined in the examination of the microstructure. In the direction of processing, the sample processed at 1.0-1.2 m/min had a reduction in width of the coatings from 1.643 to 1.293 mm and along the height it reduced to 0.375 at 2% Fe and 1% Mn. Increase in the percentage of both Fe and Mn increased the width of the coating to 1.833 mm at 1.0 m/min while the height continued to reduce to minimum of 0.272 mm at 1.2 m/min respectively.