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Due to loss of structural strengthening at temperatures beyond 250°C, heat-treated aluminium alloys (e.g. AA 6061-T6) weldments are usually characterized with poor mechanical properties including hardness, tensile and impact strengths. In... more
Due to loss of structural strengthening at temperatures beyond 250°C, heat-treated aluminium alloys (e.g. AA 6061-T6) weldments are usually characterized with poor mechanical properties including hardness, tensile and impact strengths. In this work, friction stir weldments of AA 6061-T6 reinforced with the additions of SiC, B4C and Al2O3 particles at the joints were produced and investigated for improved hardness, tensile strength and impact strength over the unreinforced weldment. The results showed that the entire reinforced welded joint exhibited improved hardness because of the enhanced metal matrix grain refinement and inherent high hardness of the reinforcement particles. B4C particle addition produced hardest joint of about 81% of the base metal hardness (∼114 HV0.3). The impact energies of the SiC (16.9 J), B4C (16.5) and Al2O3 (12.2 J) reinforced weldments are closer to that of the base metal (18.6 J) compared with the unreinforced weldment (9.6 J). The reinforced weldments...
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In this study, a new material combination is evaluated for use with selective laser melting (SLM) methods of additive manufacturing. A 10 wt.% fine TiB2 powder was satellited onto the surface of a 90 wt.% Ti-6Al-4V powder to prevent... more
In this study, a new material combination is evaluated for use with selective laser melting (SLM) methods of additive manufacturing. A 10 wt.% fine TiB2 powder was satellited onto the surface of a 90 wt.% Ti-6Al-4V powder to prevent segregations and promote homogeneity during processing. Solid structures of TiB2/Ti-6Al-4V were built using SLM Realiser 50 machine. Thereafter, the built structures were subjected to microstructural examination using optical and scanning electron microscopies. The hardness of the structure was determined using Vickers hardness tester. Results revealed that there was a reactive decomposition of the TiB2 powder which led to the formation of short (length ≤ 10 μm) and long (20-25 μm) TiB whiskers as reinforcements in the composites. The composite hardness was measured to vary from 440-503 HV0.3, signifying 30% increase when compared to Ti-6Al-4V hardness (350 HV0.3). Hence, processing satellited feedstock via SLM is promising for future product development.
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The purpose of this study is to investigate the effect of different reinforcement strategies on the mechanical properties of pulverized glass waste (PGW) reinforced AA6061-T6 friction stir welded joint. Friction stir welding of PGW... more
The purpose of this study is to investigate the effect of different reinforcement strategies on the mechanical properties of pulverized glass waste (PGW) reinforced AA6061-T6 friction stir welded joint. Friction stir welding of PGW reinforced AA6061-T6 was carried out at an optimized processing parameters by using different reinforcement strategies including centre groove, parallel holes, centre holes, zig-zag holes and side holes arrangements. Thereafter, the microstructure and mechanical properties of weldments produced using each strategy were investigated. The results showed that all the reinforcement strategies utilized in this work produced harder joints than the unreinforced joint. The parallel holes (PH) strategy followed by the centre holes (CH) exhibited the highest hardness of 72 HRCB and 66 HRCB respectively. Only the joints produced using PH, CH and SH strategies exhibited higher or improved impact energy than the unreinforced. Though the joints produced using PH and CH...
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Abstract Aluminium alloys are one of the choice materials with ever-increasing demands in manufacturing industries. The aluminium alloy 6 xx series such as AA6061-T6, has emerged as one of the promising materials utilized owing to its... more
Abstract Aluminium alloys are one of the choice materials with ever-increasing demands in manufacturing industries. The aluminium alloy 6 xx series such as AA6061-T6, has emerged as one of the promising materials utilized owing to its combination of favourable properties which include high strength to weight ratio, good ductility, excellent corrosion resistance and relatively low cost. These superior properties are responsible for its emergence and usage in the fabrication of aircraft wings and fuselages, yacht/ship construction, automotive rims and wheel spacers. However, joining of AA6061-T6 including the use of friction stir welding (FSW) has serious concerns because the mechanical and tribological properties of the AA6061-T6 welded joints deteriorate significantly compared with the base metal. This phenomenon has been attributed to the severe softening encountered at the stir zone (SZ) of the aluminium matrix during FSW. Other inherent challenges of FSW such as weld thinning, kissing bond and keyhole formation also contribute to the reduction in the weld joint quality. The softening phenomenon has been linked to the dissolution of the strengthening precipitates (B″-Mg5Si6) as a result of high heat input during the welding process. Hence, this paper attempts to review the various improvement strategies adopted in the existing studies to improve the quality of AA 6061-T6 welded joint. These include parametric optimization, selection of appropriate tool design, pre and post heat treatments, adoption of different groove/hole designs for particle addition as well as the addition of reinforcement particles to the weld joint. The variants of FSW recently developed will also be considered. The findings from the review will generally be useful for future work on FSW of heat treated aluminium alloys. The evolution of FSW and its associated challenges are briefly discussed while the research areas yet to be harnessed are suggested for future works.
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Purpose The purpose of this study is to conduct gas tungsten arc dissimilar welding of AISI 304 stainless steel and low carbon steel within a process window so as to investigate the effects of current, speed and gas flow rate (GFR) on the... more
Purpose The purpose of this study is to conduct gas tungsten arc dissimilar welding of AISI 304 stainless steel and low carbon steel within a process window so as to investigate the effects of current, speed and gas flow rate (GFR) on the microstructure and mechanical properties of the weldments. Design/methodology/approach The welding experiment was carried out at different combinations of parameters using WN-250S Kaierda electric welding machine. A combination of scanning electron microscopy and energy dispersive X-ray spectroscopy was used to examine the microstructure of the weldments. Micro-hardness and tensile tests were performed using Vickers hardness tester and Instron universal testing machine, respectively. ANOVA was used to analyze the significance of the parameters on the mechanical properties. Findings The microstructure of the weld region is characterized with dendritic structure with the existence of ferrite and austenite phases. The utilized parameters show signific...
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In this work, gas metal arc welding of AISI 304 stainless steel at varying compositions of argon-CO2 shielding environment was performed using an established optimum parametric combination. Thereafter, investigations on the microstructure... more
In this work, gas metal arc welding of AISI 304 stainless steel at varying compositions of argon-CO2 shielding environment was performed using an established optimum parametric combination. Thereafter, investigations on the microstructure of the welded joints and mechanical properties of the weldments were carried out. Weldments of excellent surface quality that are void of spatters and pores were obtained when the shielding gas composition (wt.%) range is between 100% argon and 75% argon - 25% CO2. Increasing percentage composition of CO2 beyond 25% resulted in irregular bead formation characterized with spatters and pores. The hardness of the welded joint became significantly high as the CO2 composition in the shielding gas increased. The highest value of 310 HV was obtained when the shielding gas composition was 5% argon- 95% CO2. The least (220 HV) was obtained when the shielding gas was 100% argon. High ultimate tensile strength (596 - 378 MPa) was achieved when the shielding g...
Obtaining high-quality AA6061-T6 weldment is difficult because of the dissolution of its strengthening precipitates at temperatures beyond 250°C. In this work, the surface quality, mechanical and wear properties of AA6061-T6 friction stir... more
Obtaining high-quality AA6061-T6 weldment is difficult because of the dissolution of its strengthening precipitates at temperatures beyond 250°C. In this work, the surface quality, mechanical and wear properties of AA6061-T6 friction stir welded joints at varying SiC addition (0.56-1.72 g) and number of weld passes (1-6) were investigated and discussed. SiC content was varied by changing the center groove width (CGW). Also, microstructure analysis of the entire welded joints was performed. For the first time, a process map predicting the surface characteristics of SiC reinforced AA6061-T6 friction stir welded joint at varying combinations of CGW and number of weld passes was developed. Increasing the number of passes resulted in better matrix refinement, particles fragmentation and improved particles distribution while increase in SiC content produced particles clustering and lower particles fragmentation. All the reinforced joints showed higher hardness but lower ductility than the unreinforced joint. Only joints reinforced with 0.56 g SiC showed improved tensile strength than the unreinforced joint (156 MPa) with the highest value of ~196 MPa (67% of the base metal) obtained at 4 weld passes. Increased hardness and tensile strength obtained as the weld passes increased from 2 to 4 was traced to better grain refinement, improved particles distribution and fragmentation. However, slight reduction in these properties at 6 passes was observed. Ductile fracture mode was found in all the joints except for joints reinforced with 1.01-1.72 g of SiC that showed evidence of brittle fracture. The specific wear rates of the entire reinforced joints are lower than that of the unreinforced joint. The weldment formed with 0.56 g SiC addition at 4 weld passes exhibited the best combination of properties among the entire weldments.
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In this paper, the development of an automated mechanical lift for material handling purposes in a manufacturing environment was carried out and reported. The lift was designed for a rated load capacity of 10 kg which required a 1-hp... more
In this paper, the development of an automated mechanical lift for material handling purposes in a manufacturing environment was carried out and reported. The lift was designed for a rated load capacity of 10 kg which required a 1-hp electric motor. The power transmission was achieved using belt-pulley, worm gear and chain-sprocket mechanisms; and the system automation was achieved using contactors and limit switches. The performance evaluation of the system revealed that the relationship between the time required to raise and to return loads within a range of 5–15 kg through a distance of 1070 mm followed a third-order polynomial with high correlation coefficients of 0.996 and 0.998 respectively. The trend polynomial curve that characterized the lifting behaviour was found to have three regions. The first region had a slope of 0.25 sec/kg which decreased gradually to near zero, the second region had a near-zero slope over a load range of 7–10.60 kg and a consistent travel time of about 5.67 ± 0.03 sec, and the third region had a slope which increased from near zero to 0.64 sec/kg. The automated mechanical lift developed could successfully carry out the vertical displacement of materials, hence fulfilling the design purpose.
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With the world trade agreements and the resulting of global competitions among the manufacturers through massive exchange of goods across the national borders, many sectors of Nigerian manufacturing industries particularly, small scale... more
With the world trade agreements and the resulting of global competitions among the manufacturers through massive exchange of goods across the national borders, many sectors of Nigerian manufacturing industries particularly, small scale companies have virtually collapsed. In view of the fact that Lean Manufacturing (LM) thinking enables manufacturers to combine the good features of mass and craft production by mass producing goods at low cost and quickly reconfigure to accommodate a variation in product mix and design could be a way out for the ailing small-scale manufacturing companies. This paper presents the level of awareness and implementation of some selected LM tools/practices within the Nigerian Small-Scale Manufacturers (NSSMs). A field survey with a structured questionnaire, interviews and site visits were conducted to get necessary information from the respondents. One hundred small-scale companies were selected purposely to represent the best scenario of LM practices within Nigerian small-scale manufacturing companies. The findings revealed that the awareness and implementation levels of 5S, Kaizen, Kaban pull system and value stream mapping are very low whereas team work, staff training and visual management are extremely known therefore their implementation levels are high. Lack of full understanding of lean principles, high logistic problem in Nigeria, cost of implementation and large communication gap between the manufacturers and their suppliers and customers are identified as main barriers to full implementation of the LM tools within NSSMs.
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ABSTRACT Degradation and subsequent failure of rail tracks are commonly caused by rolling contact fatigue among other mechanisms of wear. Rail crossings are known to exhibit more of these failures due to increased localised traffic and... more
ABSTRACT Degradation and subsequent failure of rail tracks are commonly caused by rolling contact fatigue among other mechanisms of wear. Rail crossings are known to exhibit more of these failures due to increased localised traffic and environmental conditions. A high proportion of the costs associated with the repair of rail tracks was due to the rolling contact fatigue phenomenon. In order to mitigate these costs, laser cladding of worn regions has been proposed for the repair of used tracks in situ to limit the need for them to be replaced and for the preservice protection of newly rolled rails and cast crossings. A Co–Cr, Stellite 6, alloy is chosen to demonstrate repair and also surface coating/protection of R260 rail steel. Results showed that cladded Stellite 6 possessed improved hardness, good tribological performance and excellent workhardening ability when compared with rail steel. These demonstrate laser cladding as a viable solution for repair worn rail track.
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Research Interests: Engineering and Emerging
Research Interests: Heat and carbonitriding
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In this paper, the level of awareness of AM/RP technology in south-western Nigeria was investigated and presented. In a survey, copies of a questionnaire were administered to sixty (60) engineering personnel in research/tertiary... more
In this paper, the level of awareness of AM/RP technology in south-western Nigeria was investigated and presented. In a
survey, copies of a questionnaire were administered to sixty (60) engineering personnel in research/tertiary institutions in
the south-western states in Nigeria and forty (40) useful responses were obtained and analyzed. The analysis indicated that
there was 40% awareness of AM/RP technology in the south-western Nigeria, whereas 60% of the respondents had not
previously heard of the technologies. It was further deduced that the highest level of awareness of 50% was for inkjet/
3D printing, amongst other forms of AM/RP technology in the south-western states in Nigeria. The analysis of the
availability of AM equipment indicated that only 5% of the respondents speci
fi
ed that their institutions in south-western
Nigeria possessed inkjet/3D printing AM equipment. This was at one research institute in south-western Nigeria.
Though, the amount of AM/RP equipment installed is small at the moment, the level of awareness of this technology is
fairly high and it is expected that the awareness level will keep increasing as concerted efforts towards procurement of
AM/RP systems from abroad and by local fabrication/production is made to promote rapid product development.
survey, copies of a questionnaire were administered to sixty (60) engineering personnel in research/tertiary institutions in
the south-western states in Nigeria and forty (40) useful responses were obtained and analyzed. The analysis indicated that
there was 40% awareness of AM/RP technology in the south-western Nigeria, whereas 60% of the respondents had not
previously heard of the technologies. It was further deduced that the highest level of awareness of 50% was for inkjet/
3D printing, amongst other forms of AM/RP technology in the south-western states in Nigeria. The analysis of the
availability of AM equipment indicated that only 5% of the respondents speci
fi
ed that their institutions in south-western
Nigeria possessed inkjet/3D printing AM equipment. This was at one research institute in south-western Nigeria.
Though, the amount of AM/RP equipment installed is small at the moment, the level of awareness of this technology is
fairly high and it is expected that the awareness level will keep increasing as concerted efforts towards procurement of
AM/RP systems from abroad and by local fabrication/production is made to promote rapid product development.
Laser metal deposition using wire feeding system is increasingly becoming known as a process for making engineering components from the scratch. The process quality determines the end properties of the components hence,... more
Laser metal deposition using wire feeding system is increasingly becoming known as a process for
making engineering components from the scratch. The process quality determines the end properties of
the components hence, their lifetime performances in the service environments. In this study, single
tracks and multiple tracks (walls) of AISI 308LSi on AISI 304 substrate were laser deposited using lateral
wire feeding system. The microstructures of the deposited tracks were examined using optical
microscopy and scanning electron microscopy. The macrohardness at different stages of the built walls
was determined using Vickers hardness tester, while the ultimate tensile strength of the walls was
investigated according to ASTM E8M-13 standard. The microstructure of the walls revealed nearly vertical
columnar dendrites growing perpendicularly to the horizontal. The macrohardness of the deposited walls is within 167–194 HV butd ecreased from the bottom layer to the top layer. The tensile strength of the walls which ranges between 474 and 525 MPa depends on the wall building directions.
making engineering components from the scratch. The process quality determines the end properties of
the components hence, their lifetime performances in the service environments. In this study, single
tracks and multiple tracks (walls) of AISI 308LSi on AISI 304 substrate were laser deposited using lateral
wire feeding system. The microstructures of the deposited tracks were examined using optical
microscopy and scanning electron microscopy. The macrohardness at different stages of the built walls
was determined using Vickers hardness tester, while the ultimate tensile strength of the walls was
investigated according to ASTM E8M-13 standard. The microstructure of the walls revealed nearly vertical
columnar dendrites growing perpendicularly to the horizontal. The macrohardness of the deposited walls is within 167–194 HV butd ecreased from the bottom layer to the top layer. The tensile strength of the walls which ranges between 474 and 525 MPa depends on the wall building directions.
Laser metal deposition using wire feeding system is increasingly becoming known as a process for making engineering components from the scratch. The process quality determines the end properties of the components hence,... more
Laser metal deposition using wire feeding system is increasingly becoming known as a process for
making engineering components from the scratch. The process quality determines the end properties of
the components hence, their lifetime performances in the service environments. In this study, single
tracks and multiple tracks (walls) of AISI 308LSi on AISI 304 substrate were laser deposited using lateral
wire feeding system. The microstructures of the deposited tracks were examined using optical
microscopy and scanning electron microscopy. The macrohardness at different stages of the built walls
was determined using Vickers hardness tester, while the ultimate tensile strength of the walls was
investigated according to ASTM E8M-13 standard. The microstructure of the walls revealed nearly vertical
columnar dendrites growing perpendicularly to the horizontal. The macrohardness of the deposited walls
is within 167–194 HV but decreased from the bottom layer to the top layer. The tensile strength of the
walls which ranges between 474 and 525 MPa depends on the wall building directions.
making engineering components from the scratch. The process quality determines the end properties of
the components hence, their lifetime performances in the service environments. In this study, single
tracks and multiple tracks (walls) of AISI 308LSi on AISI 304 substrate were laser deposited using lateral
wire feeding system. The microstructures of the deposited tracks were examined using optical
microscopy and scanning electron microscopy. The macrohardness at different stages of the built walls
was determined using Vickers hardness tester, while the ultimate tensile strength of the walls was
investigated according to ASTM E8M-13 standard. The microstructure of the walls revealed nearly vertical
columnar dendrites growing perpendicularly to the horizontal. The macrohardness of the deposited walls
is within 167–194 HV but decreased from the bottom layer to the top layer. The tensile strength of the
walls which ranges between 474 and 525 MPa depends on the wall building directions.