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Effect of starting powder particle size and heating rate on spark plasma sintering of Fe- Ni alloys

- Shongwe,M.B., Ramakokovhu, M.M., Diouf, S., Durowoju, M.O., Obadele, B.A., Sule, R., Olubambi, P.A, Sadiku, E.R.

  • Authors: Shongwe,M.B. , Ramakokovhu, M.M. , Diouf, S. , Durowoju, M.O. , Obadele, B.A. , Sule, R. , Olubambi, P.A , Sadiku, E.R.
  • Date: 2016
  • Subjects: Densification , Sintering , Microstructure
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/123446 , uj:20792 , Citation: Shongwe,M.B. et al. 2016. Effect of starting powder particle size and heating rate on spark plasma sintering of Fe- Ni alloys.
  • Description: Abstract: The effect of starting powder particle size and heating rate on spark plasma sintering of Fe-Ni alloys was investigated, with the particle powder size varying from 3 to 70 μm and heating rate from 50 to 150 °C/min. The effect of the starting powder particle size was more obvious when comparing 3-FeNi and 70-FeNi at all heating rates, with the former having better density and hardness than the latter. Sintered densities close to theoretical (≥ 99%) were achieved for a heating rate of 50°C/min for the different starting particle size powders, and decreased with increasing heating rate. The average grain size of alloys sintered at 150°C/min was ~34% smaller than those sintered at 50°C/min. The porosity content of the sintered samples increased with increasing heating for the same particle size. The shrinkage rate depends on both heating rate and particle size. At a particle size of 3 μm and a heating rate of 50oC/min, three peaks were observed indicative of the phenomena responsible for good densification. As the heating rate increases, only two peaks and one peak are observed at heating rates of 100 and 150oC/min, respectively. This suggests that, unlike high heating rates, the longer processing time at low heating rate allows the three phenomena to take place. The hardness measurement revealed a steady decrease with increasing heating rate. At a heating rate of 150°C/min the particles were well packed but no typical dimple structure of a ductile material was observed. However, for samples sintered at 50 and 100°C/min a typical dimple fracture morphology was observed.
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A comparative study of spark plasma sintering and hybrid spark plasma sintering of W-4.9ni-2.1Fe heavy alloy

- Shongwe, Mxolisi Brendon, Diouf, Saliou, Durowoju, Mondiu Olayinka, Olubambi, Peter Apata, Ramakokovhu, Munyadziwa Mercy, Obadele, Babatunde Abiodun

Microstructure and mechanical characterization of in situ synthesized AA6061/(TiB2+Al2O3) hybrid aluminum matrix composites

- Selvam, J. David Raja, Dinaharan, I., Vibin Philip, S., Mashinini, P. M.

The influence of scanning speed and number of scans on the properties of laser formed steel

- Sanusi, Kazeem Oladele, Akinlabi, Stephen, Akinlabi, Esther Titilayo

Microstructural characterization and hardness properties of magnesium alloy processed by high pressure torsion

- Sanusi, Kazeem O., Madushele, Nkosinathi, Akinlabi, Esther Titilayo

Effect of heat treatment on microstructure and mechanical properties of magnesium alloy

- Sanusi, Kazeem O., Madushele, Nkosinathi, Akinlabi, Esther Titilayo

Gas flow rate and powder flow rate effect on properties of laser metal deposited Ti6Al4V

- Pityana, Sisa, Mahamood, Rasheedat M., Akinlabi, Esther Titilayo, Shukla, Mukul

  • Authors: Pityana, Sisa , Mahamood, Rasheedat M. , Akinlabi, Esther Titilayo , Shukla, Mukul
  • Date: 2013
  • Subjects: Gas flow rate , Microhardness , Microstructure , Powder flow rate , Laser metal deposition , Additive manufacturing technology
  • Type: Article
  • Identifier: uj:4849 , http://hdl.handle.net/10210/12516
  • Description: Tracks of Ti6Al4V powder were deposited on Ti6Al4V substrate using Laser Metal Deposition (LMD) process, an Additive Manufacturing (AM) manufacturing technology, at a laser power and scanning speed maintained at 1.8 kW and 0.005 m/s respectively. The powder flow rate and the gas flow rate were varied to study their effect on the physical, metallurgical and mechanical properties of the deposits. The physical properties studied are: the track width, the track height and the deposit weight. The mechanical property studied is the Microhardness profiling using Microhardness indenter at a load of 500g and dwelling time of 15 μm. The metallurgical property studied is the microstructure using the Optical microscopy. This study revealed that as the powder flow rate was increased, the track width, track height and the deposit weight were increased while as the powder flow rate was increased, the track width, track height and the deposit weight decreased. The results are presented and discussed in detail.
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An Overview of TIG Welding of Ti6Al4V : Recent Developments

- Omoniyi, Peter O., Mahamood, Rasheedat M., Jen, Tien-Chien, Akinlabi, Esther T.

Microstructural and mechanical properties of spark plasma sintering of Ni2 Cr11Al powders synthesized by mechanical alloying for thermal barrier coating

- Omoniyi, F. I. S., Olubambi, P. A., Sadiku, R. E.

Influence of aluminium content on the microstructure and densification of spark plasma sintered nickel aluminium bronze

- Okoro, Avwerosuoghene Moses, Lephuthing, Senzeni Sipho, Oke, Samuel Ranti, Olubambi, Peter Apata

Effect of water flow rate on the yield strength of a reinforced bar

- Musonda, Vincent, Akinlabi, Esther Titilayo, Jen, Tien-Chien

  • Authors: Musonda, Vincent , Akinlabi, Esther Titilayo , Jen, Tien-Chien
  • Date: 2017
  • Subjects: Hot rolling , Microstructure , Rebar
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://ujcontent.uj.ac.za8080/10210/370699 , http://hdl.handle.net/10210/243763 , uj:25198 , Citation: Musonda, V., Akinlabi, E.T. & Jen, T.C. 2017. Effect of water flow rate on the yield strength of a reinforced bar. Advances in Engineering Research (AER), volume 102, Second International Conference on Mechanics, Materials and Structural Engineering (ICMMSE 2017).
  • Description: Abstract: High strength requirement of Thermo-mechanically treated (TMT) rebars is crucial in the construction of flyovers, bridges and high rise buildings because of the good combination of the mechanical properties. The yield strength is expected to be between 450 MPa and 550 MPa after the hot rolling process depending on prescribed standards. A series of experimental trials during a hot rolling process were carried out in a steel plant in which parameters such as the water flow rate and the processing time were varied to study their effect on the evolving mechanical properties of the rebars. Four “heats”(A “heat” is a batch of molten steel, referred to as tap to tap cycle and involves furnace charging with scrap, melting, deslagging, tapping molten steel and furnace turn-around. Furnace turn-around is the period following completion of tapping until the furnace is recharged for the next “heat”) were done to produce Y 12 mm reinforced bars (rebars). For every “heat” done, tensile tests were carried out on the samples every after 15 minutes to establish the yield strength of the rebar. At least eight samples were tested in every “heat”. It was observed that some samples showed low values of yield strength (< 450 MPa) which falls short of the minimum guaranteed yield strength. It was further noted that the water flow rate in the water cooling chamber was far below 600 m􀬷⁄h for this size of rebar in some cases. A series of these tests were conducted and the water flow rate adjusted in order to arrive at the optimum flow rate corresponding to the expected yield strength and microstructure. The quenching time in the water cooling chamber was in the range 0.1 to 0.5 seconds and the results obtained both for the tensile tests and microstructure after several adjustments to the flow rate in particular yielded optimum results consistent with prescribed standards.
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Effect of weight per meter of reinforced bar on mechanical properties and microstructure

- Musonda, V., Akinlabi, Esther Titilayo, Jen, T.C.

  • Authors: Musonda, V. , Akinlabi, Esther Titilayo , Jen, T.C.
  • Date: 2017
  • Subjects: Billets , Hot rolling , Microstructure
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/241963 , uj:24945 , Citation: Musonda, V., Akinlabi, E.T. & Jen, T.C. 2017. Effect of weight per meter of reinforced bar on mechanical properties and microstructure.
  • Description: Abstract: Reinforced bars (rebars) are Thermo-mechanically treated (TMT) bars hot rolled from steel billets produced from scrap melted in an Electric Arc Furnace (EAF) at a temperature of about 1600 ℃ (usually 1580℃). Weight per meter of a low carbon steel rebar is one aspect which has been neglected by some steel producers during the tensile testing in the rod mill. Determination of weight per metre is explicitly required for a TMT rebar. Any reduction in mass will mean a lowering in capacity of the steel reinforcing bar. A series of “heat” numbers or batches of molten steel from an EAF for the production of steel sample A, (Y10 and Y 12 rebars), were observed at a Steel plant to investigate the effect of weight per meter of reinforced bar on the mechanical properties and microstructure. The rolling speed range was 3m/s to 14 m/s for different “heats”. Two other steel samples B and C were sourced from the local market to compare with Sample A. Samples collected from different sources on the local market, however, showed lower values of weight per meter different from the prescribed standards. This did not only affect the ultimate tensile strengths which were higher than normal but also the microstructure which deviated from the standard for this material. Sample A, did not only show a good combination of tensile strength and yield stress of 450MPa and a maximum tensile strength of 650MPa but also a standard pearliteferrite microstructure, while sample B and C exhibited excessive high strengths and brittle behaviour and can be prone to failure.
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Property evolution of thermo-mechanically treated reinforcement bar

- Musonda, V., Akinlabi, Esther Titilayo

  • Authors: Musonda, V. , Akinlabi, Esther Titilayo
  • Date: 2018
  • Subjects: Property evolution , Microstructure , Reinforcement bars
  • Language: English
  • Type: Conference proceeding
  • Identifier: http://hdl.handle.net/10210/291125 , uj:31608 , Citation: Musonda, V. & Akinlabi, E.T. 2018. Property evolution of thermo-mechanically treated reinforcement bar.
  • Description: Abstract: Property evolution of microstructure of reinforcement bar (rebar) depends on how well the steel is treated during and after the Thermomechanical Treatment (TMT) box. Rebars are hot rolled - from low carbon steel through Tempcore technology. In order to achieve optimal properties, typical evolving mechanical properties of the rebar such as ultimate tensile strength (UTS), yield stress (YS) and the percentage elongation (%El) were conducted. This is necessary to control the tempering and cooling process. In this study, a simulation of the cooling rebar was investigated using finite element modelling (FEM). The material used for the model and production of the rebar was equivalent to AISI 1016 carbon steel and was produced from scrap supplemented with Direct Reduced Iron (DRI). The raw materials were melted in an Electric Arc Furnace (EAF) prior to hot rolling through a billet caster. The rod mill tensile test report showed that UTS and YS values ranged between 482 MPa for the YS and 650 MPa for UTS on an average. The average percentage elongation was found to be 23 % well above the 14 % threshold according to the standard. The pearlite-ferrite microstructure and the martensite developed is in agreement with the standard microstructure found in the literature.
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Production and characterization of titanium carbide particulate reinforced AA6061 aluminum alloy composites using stir casting

- Moses, J. Jebeen, Dinaharan, I., Sekhar, S. Joseph

Microstructure evolution and mechanical characterization of friction stir welded titanium alloy Ti–6Al–4V using lanthanated tungsten tool

- Mashinini, P. M., Dinaharan, I., Selvama, J. David Raja, Hattingh, D. G.

Influence of scanning speed on the intermetallic produced in-situ in laser metal deposited TiC/Ti6Al4V composite

- Mahamood, Rasheedat M., Akinlabi, Esther Titilayo

Laser metal deposition of Ti6Al4V : a study on the effect of laser power on microstructure and microhardness

- Mahamood, Rasheedat M., Akinlabi, Esther Titilayo, Shukla, Mukul, Pityana, Sisa

  • Authors: Mahamood, Rasheedat M. , Akinlabi, Esther Titilayo , Shukla, Mukul , Pityana, Sisa
  • Date: 2013
  • Subjects: Laser metal deposition process , Laser power , Ti6Al4V , Macroscopic banding , Microhardness , Microstructure
  • Type: Article
  • Identifier: uj:4896 , http://hdl.handle.net/10210/12610
  • Description: The effect of laser power on the resulting microstructure and microhardness of laser metal deposited Ti6Al4V powder on Ti6Al4V substrate has been investigated. The tracks were deposited using 99.6 % pure Ti6Al4V powder of particle size ranging between 150 - 200 μm on 99.6% Ti6Al4V substrate. The laser power was varied between 0.8 - 3.0 kW while the scanning speed, powder flow rate and the gas flow rate were kept at the values of 0.005 m/sec, 1.44 g/min and 4 l /min respectively. The microstructure and the microhardness were studied using the optical microscope and the Vickers hardness tester respectively. Layer band or macroscopic banding was observed in all the samples which is phenomenon as it was only reported in the literature for multi-layer deposits. The literature attributed re-melting of the previous layers by the succeeding layers as being responsible for their formation. This study has revealed that this band could be as a result of shrinkage happening in the fusion zone as a result of the interaction of the deposited powder and the melt pool created by the substrate material. This study also reveals the relationship between the microstructure, the average microhardness and the laser power which are comprehensively discussed. The higher the laser power, the lower the density of columnar prior beta grain structure. Also the average microhardness increases as the laser power increases.
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Microstructural and electrochemical studies of spark plasma sintered multiwall carbon nanotubes reinforced TiO2eMnO2 based composite

- Lephuthing, Senzeni Sipho, Okoro, Avwerosuoghene Moses, Ige, Oladeji Oluremi, Olunambi, Peter Apata

Experimental evaluation of surface quality characteristics in laser machining of nickel-based superalloy

- Khan, Adam M., Gupta, Kapil

  • Authors: Khan, Adam M. , Gupta, Kapil
  • Date: 2019
  • Subjects: Kerf , Laser , Microstructure
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/404309 , uj:33902 , Citation: Khan, A.M. & Gupta, K. 2019. Experimental evaluation of surface quality characteristics in laser machining of nickel-based superalloy.
  • Description: Abstract: This paper reports the investigation results of CO2 laser cutting of Inconel 718 superalloy. Investigation on the effects of the two important laser parameters power and travel speed on machinability i.e. material removal rate, kerf wall inclination, and average surface roughness of Inconel 718 has been conducted. Increased kerf wall inclination has been found with slow travel speed and increasing power. Low power and high travel speed produced maximum material removal rate and minimum surface roughness. Premature state of fusion has advanced dross regime at a slow cutting speed of 3.3 m/min and leading to a surface roughness of 9.3 microns maximum. Dendrite structures were formed and changes in surface hardness were observed due to high travel speed. Therefore, based on the investigation, slow travel speed with appropriate laser power is recommended for the improved machinability and surface quality of Inconel 718 superalloys.
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Influence of laser power on improving the wear properties of laser deposited Ti-6Al-4V+B4C composite

- Erinosho, Mutiu F., Akinlabi, Esther Titilayo

  • Authors: Erinosho, Mutiu F. , Akinlabi, Esther Titilayo
  • Date: 2018
  • Subjects: Laser metal deposition , Microstructure , Wear measurement
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/273312 , uj:29114 , Citation: Erinosho, M.F. & Akinlabi, E.T. 2018. Influence of laser power on improving the wear properties of laser deposited Ti-6Al-4V+B4C composite.
  • Description: Abstract: Titanium and its alloys have possessed outstanding properties such as high specific strength, good oxidation and corrosion resistance; which have made them extensively suitable for use in the aeronautical, medical, automobile, marine and chemical industries. This paper presents the impact of laser power on the microstructure and the wear properties of titanium matrix Ti-6Al-4V+B4C composites. The laser powers were varied between 0.8 kW and 2.2 kW while keeping other contributing parameters constant. The microstructural effects were characterised with increasing α-Ti lamella and coarse Widmanstettan structures as the laser power was increased; alongside with the inclusion of 20 wt % of B4C. The mechanical action during wear test has created a loop shape with inner and outer radii on the surface of the laser deposited composites. The wear thickness, depth and COF were taken into cognisance; with sample C deposited at a laser power of 1.8 kW and scanning speed of 1 m/min having the lowest wear loss of 0.119 mm3. The substrate exhibited the shallowest wear depth and the reason is attributed the compressive nature of the material. The interlace of B4C in the titanium matrix has improved the properties the laser formed composites.
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