Showing items 1 - 20 of 35

Your selections:

A comparative study of spark plasma sintering and hybrid spark plasma sintering of W-4.9ni-2.1Fe heavy alloy

A review on the influence of process parameters on powder metallurgy parts

  • Authors: Edosa, Osarue Osaruene , Tekweme, Francis Kunzi , Gupta, Kapil
  • Date: 2021
  • Subjects: Composites , Mechanical properties , Microstructure
  • Language: English
  • Type: Journal artice
  • Identifier: http://hdl.handle.net/10210/490435 , uj:44751 , Citation: Edosa, O.O., Tekweme, F.K. and Gupta, K., 2022. A review on the influence of process parameters on powder metallurgy parts. Engineering and Applied Science Research, 49(3), pp.433-443. , DIO:10.14456/easr.2022.44
  • Description: Abstract: The capability of powder metallurgy (PM) process to produce high quality components/parts is largely dependent on the control of process parameters. To obtain the desirable quality characteristics or properties in the produced part, an appropriate combination of process parameters is required. This paper presents a detailed review of powder metallurgy process parameters and their effects on a wide range of properties while developing a wide range of metallic and composites products. Key process parameters in this study include compaction pressure, sintering temperature, sintering time, sintering atmosphere, lubrication and reinforcement percentage volume. Their influence on physical properties, mechanical properties and microstructure of PM parts are extensively discussed. An extensive literature study as reported in this paper reveals that compaction pressure, sintering temperature, time and sintering atmosphere highly influence part density and strength, whereas part hardness and wear are greatly affected by hard ceramic reinforcement addition, compaction pressure, sintering temperature and time. Die wall lubrication greatly improve the physical, mechanical properties and microstructure of PM components compared to powder mass lubrication. It is observed that the powder metallurgy process conducted at optimum parameters produce quality products. This paper aims to facilitate researchers and scholars by providing a detail knowledge of PM process parameters and their effects, for them to conduct research and development to establish the field further.
  • Full Text:

An Overview of TIG Welding of Ti6Al4V : Recent Developments

Characterising the brake blocks of a freight rail container wagon

Characterising the effect of laser power on laser metal deposited titanium alloy and boron carbide

  • Authors: Erinosho, M. F. , Akinlabi, Esther Titilayo
  • Date: 2017
  • Subjects: Ti6Al4V-B4C composites , Laser metal deposition , Microstructure
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/241349 , uj:24845 , Citation: Erinosho, M.F. & Akinlabi, E.T. 2017. Characterising the effect of laser power on laser metal deposited titanium alloy and boron carbide.
  • Description: Abstract: Titanium alloy has gained acceptance in the aerospace, marine, chemical and other related industries due to its excellent combination of mechanical and corrosion properties. In order to augment its properties, a hard ceramic, boron carbide has been laser cladded with it at varying laser powers between 0.8 kW and 2.4 kW. This paper presents the effect of laser power on the laser deposited Ti6Al4V-B4C composites through the evolving microstructures and microhardness. The microstructures of the composites exhibit the formation of α-Ti phase and β-Ti phase and were elongated towards the heat affected zone. These phases were terminated at the fusion zone and globular microstructures were found growing epi! taxially just immediately after the fusion zone. Good bondings were formed in all the deposited composites. Sample A1 deposited at a laser power of 0.8 kW and scanning speed of 1 m/min exhibits the highest hardness of HV 432±27 while sample A4 deposited at a laser power of 2.0 kW and scanning speed of 1 m/min displays the lowest hardness of HV 360±18. From the hardness results obtained, ceramic B4C has improved the mechanical properties of the primary alloy.
  • Full Text:

Characterization of surface roughness of laser deposited Titanium alloy and copper using AFM

  • Authors: Erinosho, M. F. , Akinlabi, Esther Titilayo , Johnson, O. T.
  • Date: 2017
  • Subjects: AFM , LMD , Microstructure
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/251627 , uj:26211 , Citation: Erinosho, M. F., Akinlabi, E. T. & Johnson, O. T. 2017. Characterization of surface roughness of laser deposited Titanium alloy and copper using AFM.
  • Description: Abstract: Laser Metal Deposition (LMD) is the process of using the laser beam of a nozzle to produce a melt pool on a metal surface usually the substrate and metal powder is been deposited into it thereby creating a fusion bond with the substrate to form a new material layer against the force gravity. A good metal laminate is formed when the wettability between the dropping metal powder and the substrate adheres. This paper reports the surface roughness of laser deposited titanium alloy and copper (Ti6Al4V + Cu) using the Atomic Force Microscopy (AFM). This AFM is employed in order to sense the surface and produce different manipulated images using the micro-fabricated mechanical tip under a probe cartridge of high resolution. The process parameters employed during the deposition routine determines the output of the deposit. A careful attention is given to the laser deposited Ti6Al4V + Cu samples under the AFM probe because of their single tracked layers with semi-circular pattern of deposition.
  • Full Text:

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

Effect of laser power on the microstructural behaviour and strength of modified laser deposited Ti6Al4V+CU alloy for medical application

Effect of scanning speed and powder flow rate on the evolving properties of laser metal deposited ti-6al-4v/cu composites

  • Authors: Erinosho, Mutiu F. , Akinlabi, Esther Titilayo , Pityana, Sisa
  • Date: 2016
  • Subjects: Hardness , High pfr , Laser metal deposition , Microstructure , Porosity , Volume of deposited composite
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/93307 , uj:20331 , Citation: Erinosho, M.F., Akinlabi, E.T. & Pityana, S. 2016. Effect of scanning speed and powder flow rate on the evolving properties of laser metal deposited ti-6al-4v/cu composites.
  • Description: Abstract: In Laser Metal Deposition (LMD), good bonding between two similar or dissimilar materials can be achieved if the interrelationships between the processing parameters are well understood. LMD samples of titanium alloy, Ti-6Al-4V and copper, Cu were produced by varying the scanning speed and keeping other parameters constant. The deposited samples were characterized through the volume of deposited composites, microstructure, microhardness and the degree of porosity. The effect of the optimized high (powder flow rate) PFR, scanning speed varying from 0.06 m/min to 1.2 m/min and a constant power of 1kW led to a degree of porosity on the deposited composites. The varying percentages of porosities in the samples have an advance merit effect in the implantation of bones in animal and human. It was found that the existence of pores reduced as the scanning speed increases. The Vickers mirohardness was observed to increase with an increase in the scanning speed which shows an improvement in the properties of the Ti-6Al-4V/Cu composites. At low scanning velocity, the microstructure appears coarse due to the high rate of powder deposited at the same power of 1kW. The α-phase acicular microstructure decreases in size and thickness with an increase in the scanning speed. Widmanstätten structure was found in the scanning electron microscopy analyses. The results show that high PFR and low scanning speed have significantly influenced the evolving properties of the deposited composites.
  • Full Text:

Effect of scanning speed on the material characterizations of laser deposited titanium alloy and copper

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

  • 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.
  • Full Text:

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

  • 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.
  • Full Text:

Effect of weight per meter of reinforced bar on mechanical properties and microstructure

  • 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.
  • Full Text:

Estimation of surface topography and wear loss of laser metal deposited Ti6Al4V and Cu

  • Authors: Erinosho, Mutiu F. , Akinlabi, Esther Titilayo
  • Date: 2016
  • Subjects: Laser metal deposition , Microstructure , Surface roughness topography
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/214314 , uj:21265 , Citation: Erinosho, M.F & Akinlabi, E.T. 2016. Estimation of surface topography and wear loss of laser metal deposited Ti6Al4V and Cu.
  • Description: Abstract: The atomic force microscopy (AFM) analysis is a process that involves the detailed analyses of the surface of a three dimensional sample piece. A good image is always generated on such a sample once the settings are implemented correctly. And as such, the amplitude set point played a vital role in achieving a better image. For surface engineering applications, a small proportion of Cu has been added to Ti6Al4V alloy and deposited using a 2kW Ytterbium Fibre Laser. This paper presents the evolving microstructures and the surface topographies of the laser deposited Ti6Al4V/Cu alloys. The formation and the output of the microstructure depend on the laser processing parameters employed. The α-Ti lamella formed was observed to gain coarseness with respect to the increase in the laser power. The migration of the β-phase has been impeded during solidification due to the low strain hardening effect posed by the α-Ti lamella thereby limiting the further dislocation of the β-phase within the crystal structure. A clear picture of the height, amplitude and the phase shift of the scanned sample were viewed before a capture can be made. A correlation between wear loss and surface roughness has been established among the laser deposited samples.
  • Full Text:

Experimental and numerical analysis of geometrical properties of laser metal deposited titanium

  • Authors: Akinlabi, Esther Titilayo , Tayob, Mohammed A. , Pietra, Francesco
  • Date: 2016
  • Subjects: Ansys , Heat-Affected zone , Laser metal deposition , Microhardness , Microstructure , Porosity , Powder flow rate , Titanium
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/93300 , uj:20330 , Citation: Akinlabi, E.T., Tayob, M.A. & Pietra, F. 2016. Experimental and numerical analysis of geometrical properties of laser metal deposited titanium.
  • Description: Abstract: Laser metal deposition (LMD) is a manufacturing process, which can be used to manufacture a complete, fully functional part by building it up layer-by-layer using the data from a Computer-Aided-Design (CAD) file. The layer-by-layer addition can also be used to rebuild worn-out sections of existing parts, as well as to deposit protective coatings to protect parts in surface engineering. The process involves laser heating a substrate, on which a metal powder is deposited. The powder solidifies, when mixed with the substrate, thereby creating a metallurgical bond. In order to produce parts with high geometrical tolerances and desirable material properties, the process parameters have to be carefully controlled. Since the LMD process requires the interaction of parameters, it is not always easy to predict the output geometry. In this paper, the laser metal deposition process was modelled in ANSYS Parametric- Design-Language (APDL), using a transient thermal analysis, in order to determine the geometrical properties of the clad, that is, the width and the height of the resulting clad. The simulated results were then compared experimentally by depositing Commercially Pure (CP) titanium powder onto a Ti-6Al-4V substrate, in order to verify the simulation. The varying parameter in the experimental process was the powder flow rate, which was varied between 0.5-2.5g/min. In addition to the geometrical properties, the microstructure, microhardness; and the porosity levels of the deposited clads were also analyzed, in order to better determine the clad quality and integrity. The model showed good agreement in predicting both the height and the width of the clads. Porosity was noticed in all the samples with the exception of the clad deposited at the lowest powder flow rate setting of 0.5 g/min. An increase in the powder flow rate also led to a smaller fusion zone, due to a lower laser-material interaction period, which was the result of the increase in the quantity of powder causing attenuation of the beam, and less laser power being absorbed by the substrate. The smaller fusion zone meant that the clads could not bond to the substrate properly, which led to the clad in the sample produced with the highest powder flow rate falling off the substrate. There was a significant increase in the microhardness of the clad zone, which was due to a combination of alloying with Ti- 6Al-4V and a change in the microstructure to an acicular alpha martensite microstructure; while the Heat-Affected-Zone (HAZ) in the substrate only showed a slight increase in microhardness.
  • Full Text:

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

  • 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.
  • Full Text:

Forming behaviour of steel sheets after mechanical and laser beam forming

  • Authors: Akinlabi, Esther Titilayo , Shukla, M. , Akinlabi, S. A. , Kanyanga, S. B. , Chizyuka, C. M.
  • Date: 2014
  • Subjects: Laser beam forming , Mechanical forming , Microhardness , Microstructure , Tensile testing , Steel plates - Mechanical properties
  • Type: Article
  • Identifier: http://ujcontent.uj.ac.za8080/10210/379024 , uj:4998 , http://hdl.handle.net/10210/13136
  • Description: This paper reports the influencing factors and the characteristic behaviour of steel plates during both the mechanical forming and laser beam forming processes. Samples of the steel sheets were mechanically bent to 120 mm curvatures using a 20 ton capacity eccentric mechanical press at room temperature and also with the laser beam using a 4.4 kW Nd: YAG laser system at a scan speed of 1.9 m/min, beam diameter of 12 mm, laser power of 1.7 kW at 25% beam overlap using argon for cooling the irradiated surfaces. The chemical composition of both the as-received material and the formed samples were analysed by emission spectroscopy to quantify the changes in the elemental composition. The result shows a percentage increase in the carbon after the mechanical and laser forming processes when compared to the parent material. This can be attributed to the enhancement resulting from the forming processes. The formed samples were further characterized through microstructure, microhardness and tensile tests. The microstructural characterisation of the samples revealed that the grains of the mechanically formed and laser formed components are elongated, it was also observed that there is an increase in the pearlite grains of the laser formed components resulting from the thermal heating during the laser process. The microhardness profiles of the formed components showed that there is a significant percentage increase in the Vickers microhardness values of the laser formed samples when compared to the mechanically formed samples and with respect to the parent material. The laser beam forming process can be considered a more appropriate forming process in terms of the resulting material properties in this regard.
  • Full Text:

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

  • 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.
  • Full Text:

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

Influence of laser power on improving the wear properties of laser deposited Ti-6Al-4V+B4C composite

  • 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.
  • Full Text:
  • Disclaimer
  • Privacy
  • Copyright
  • Contact