Browsing by Author "Manjunath, G.K."

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Dry sliding wear behaviour of Al-5Zn-2Mg alloy processed by severe plastic deformation
(Elsevier Ltd, 2019) Manjunath, G.K.; Udaya Bhat, K.; Preetham Kumar, G.V.
Equal channel angular extrusion/pressing (ECAE/P) is an effectual technique to raise the mechanical, physical properties and resistance to wear of the materials. In this research, Al-5Zn-2Mg alloy material was ECAPed in route BC at lowest temperature. Hardness of the test material was increased after ECAE/P due to microstructure refinement. To demonstrate the wear characteristics of the Al-5Zn-2Mg alloy material after ECAE/P, wear tests (in dry sliding condition) were conducted at 2 conditions (condition 1: 19.62 N load and 1 m/s sliding speed, condition 2: 39.24 N load and 2 m/s sliding speed). The wear rate and magnitude of coefficient of friction (Î¼) were lessened after ECAE/P. Abrasive, adhesive and oxidation wear mechanisms are the predominant wear mechanisms noticed in the ECAE/P processed billets. Along with these mechanisms relocation of iron elements from the counter body (disc) to the test material was noticed. Â© 2019 Elsevier Ltd.
Effect of equal channel angular pressing on the microstructure and mechanical properties of Al-10Zn-2Mg alloy
(2018) Manjunath, G.K.; Kumar, G.V.P.; Bhat, K.U.
The current investigation is focused on evaluating the mechanical properties and the microstructure of cast Al-10Zn-2Mg alloy processed through equal channel angular pressing (ECAP). The ECAP processing was attempted at minimum possible processing temperature. Microstructural characterization was carried out in optical microscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffraction analysis. Hardness measurement and tensile tests were employed to estimate the mechanical properties. Experimental results showed that, ECAP processing leads to noticeable grain refinement in the alloy. Reasonable amount of dislocations were observed in the ECAP processed material. After ECAP processing, precipitates nucleation in the material was detected in the XRD analysis. ECAP leads to considerable enhancement in the mechanical properties of the material. After ECAP processing, microhardness of the material is increased from 144 Hv to 216 Hv. Also, after ECAP processing the UTS of the material is increased from 140 MPa to 302 MPa. The increase in the mechanical properties of the alloy after ECAP processing is due to the dislocation strengthening and grain refinement strengthening. Finally, fracture surface morphology of the tensile test samples also studied. � 2018 Author(s).
Effect of equal channel angular pressing on the microstructure and mechanical properties of Al-10Zn-2Mg alloy
(American Institute of Physics Inc. subs@aip.org, 2018) Manjunath, G.K.; Preetham Kumar, G.V.; Bhat, K.U.
The current investigation is focused on evaluating the mechanical properties and the microstructure of cast Al-10Zn-2Mg alloy processed through equal channel angular pressing (ECAP). The ECAP processing was attempted at minimum possible processing temperature. Microstructural characterization was carried out in optical microscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffraction analysis. Hardness measurement and tensile tests were employed to estimate the mechanical properties. Experimental results showed that, ECAP processing leads to noticeable grain refinement in the alloy. Reasonable amount of dislocations were observed in the ECAP processed material. After ECAP processing, precipitates nucleation in the material was detected in the XRD analysis. ECAP leads to considerable enhancement in the mechanical properties of the material. After ECAP processing, microhardness of the material is increased from 144 Hv to 216 Hv. Also, after ECAP processing the UTS of the material is increased from 140 MPa to 302 MPa. The increase in the mechanical properties of the alloy after ECAP processing is due to the dislocation strengthening and grain refinement strengthening. Finally, fracture surface morphology of the tensile test samples also studied. Â© 2018 Author(s).
Effect of multidirectional forging on grain structure and mechanical properties of hypereutectic Al–20%Si alloys with added refiners and modifiers; Effet du forgeage multidirectionnel sur la structure des grains et les propriétés mécaniques des alliages hypereutectiques Al-20%Si avec des agents d’affinage et modificateurs ajoutés
(Taylor and Francis Ltd., 2025) Nagaraj, C.; Dutt, K.M.; Manjunath, G.K.; Sharath, P.C.; Sollapur, S.B.; B R, B.K.; Kumar, B.; Arunkumar, D.T.
The present work is focused on the multidirectional forging (MDF) of Al–20 wt-% Si alloys with the addition of refiners and modifiers. The MDF process was performed at 200°C with a cumulative strain of 0.63. Microstructural characterization and mechanical performance were evaluated on the Al–20Si, Al–20Si–4.5Cu, Al–20Si–4.5Cu–1(Al–Ti–B), Al–20Si–4.5Cu–1(Al–Ti–B)–10(Al–Sr). The microstructure analysis revealed significant changes in the eutectic and primary phase refinement. The micro-Vickers hardness confirmed that the MDF process resulted in increased hardness (125 ± 1.9 VHN) compared to the homogenized samples (96 ± 2.7 VHN). Tensile test results showed that with the accumulation of strain, ultimate tensile strength increased to 435 MPa from 302 MPa with reduction in the percentage of elongation from 7.8 to 5.6. The grains were more uniformly distributed with addition of modifiers, and refiners further reduced the nucleation number of eutectic grains. The wear study demonstrated that the wear resistance is more in the Al–Si-Cu-Sr sample due to the increased level of hardness. The combination of multidirectional forging techniques with judicious incorporation of refiners and modifiers engenders a synergistic enhancement of microstructural integrity, hardness profiles, and wear-resistant properties in hypereutectic Al-20Si alloys. © 2024 Canadian Institute of Mining, Metallurgy and Petroleum.
Effect of zinc content on the microstructure and mechanical properties of Al-Zn-Mg alloy
(Elsevier Ltd, 2022) Manjunath, G.K.; Udaya Bhat, K.; Preetham Kumar, G.V.
In the present work, Aluminium-Zinc-Magnesium alloys (5 wt%, 10 wt% and 15 wt% Zinc and 2 wt% Magnesium) were prepared by casting process in a metal die. After casting process, heat treatment was conducted to the prepared alloys. To study the consequence of Zinc on the prepared alloys microstructure and mechanical properties were investigated. In as-cast state, in all three compositions, dendrite formation was noticed. While, after homogenization heat treatment, grain boundaries were noticed. Rise in the Zinc in the material leads to enhance the secondary particles. Microhardness and tension experiments were conducted to investigate the mechanical properties. Rise in the Zinc in the material leads to enhance the microhardness and tension strength. But ductility of the material declined with rise in the Zinc in the material. © 2021
Evolution of Tribological Properties of Cast Alâ€“10Znâ€“2Mg Alloy Subjected to Severe Plastic Deformation
(Springer Science and Business Media Deutschland GmbH, 2020) Manjunath, G.K.; Preetham Kumar, G.V.; Udaya Bhat, K.
In the current investigation, tribological behaviour of the cast Alâ€“10Znâ€“2Mg alloy processed by severe plastic deformation (SPD) technique was studied. In this work, one of the SPD techniques, equal channel angular pressing (ECAP) was adopted as a processing tool. ECAP was carried out in route BC and processing was attempted at the lowest temperature. After ECAP, grain structure of the material was refined and considerable improvement in the microhardness of the alloy was perceived. Mainly, wear resistance of the alloy material was enhanced with successive ECAP passes. Coefficient of friction of the alloy material was decreased with successive ECAP passes. Wear resistance of the alloy was decreased with a rise in the applied load and the sliding speed. Both at low and high load condition, abrasive wear was noticed in as-cast and homogenized specimens. Whereas in ECAPed specimens, in addition to abrasive wear, oxidation wear and adhesive wear were observed in low load and it changes to abrasive wear at high load. In the ECAPed specimens, at low load transfer of iron particles from the steel disc surface to the specimen surface was identified. Â© 2020, Springer Nature Singapore Pte Ltd.
Evolution of Tribological Properties of Cast Al�10Zn�2Mg Alloy Subjected to Severe Plastic Deformation
(2020) Manjunath, G.K.; Preetham, Kumar, G.V.; Udaya, Bhat, K.
In the current investigation, tribological behaviour of the cast Al�10Zn�2Mg alloy processed by severe plastic deformation (SPD) technique was studied. In this work, one of the SPD techniques, equal channel angular pressing (ECAP) was adopted as a processing tool. ECAP was carried out in route BC and processing was attempted at the lowest temperature. After ECAP, grain structure of the material was refined and considerable improvement in the microhardness of the alloy was perceived. Mainly, wear resistance of the alloy material was enhanced with successive ECAP passes. Coefficient of friction of the alloy material was decreased with successive ECAP passes. Wear resistance of the alloy was decreased with a rise in the applied load and the sliding speed. Both at low and high load condition, abrasive wear was noticed in as-cast and homogenized specimens. Whereas in ECAPed specimens, in addition to abrasive wear, oxidation wear and adhesive wear were observed in low load and it changes to abrasive wear at high load. In the ECAPed specimens, at low load transfer of iron particles from the steel disc surface to the specimen surface was identified. � 2020, Springer Nature Singapore Pte Ltd.
Flow Properties of Cast Al-Zn-Mg Alloys Subjected to Equal Channel Angular Pressing
(2018) Manjunath, G.K.; Preetham, Kumar, G.V.; Udaya, Bhat, K.
Flow stress can be described as the stress necessary to continue deformation at any stage of plastic strain. The strength coefficient (K) and strain-hardening exponent (n) are the two important flow properties of the material. In the present work, flow properties of three different cast Al-Zn-Mg alloys processed by equal channel angular pressing (ECAP) were investigated. ECAP processing was carried out in a die having ? = 120� and ? = 30�. After ECAP processing, significant grain refinement and increase in the hardness was observed. Compression test was used to determine the flow properties of ECAP processed samples. Force-stroke data was recorded from the compression test. Flow curves were drawn by using force-stroke data. Strength coefficient and strain-hardening exponent were determined from the log-log plot of true stress-strain curves. Significant increase in the strength coefficient was observed after ECAP processing. Also, the strength coefficient is increased when the zinc content is increased in the alloy. Strain-hardening exponent was decreased with increase in the number of ECAP passes. � Published under licence by IOP Publishing Ltd.
Flow Properties of Cast Al-Zn-Mg Alloys Subjected to Equal Channel Angular Pressing
(Institute of Physics Publishing helen.craven@iop.org, 2018) Manjunath, G.K.; Preetham Kumar, G.V.; Udaya Bhat, K.
Flow stress can be described as the stress necessary to continue deformation at any stage of plastic strain. The strength coefficient (K) and strain-hardening exponent (n) are the two important flow properties of the material. In the present work, flow properties of three different cast Al-Zn-Mg alloys processed by equal channel angular pressing (ECAP) were investigated. ECAP processing was carried out in a die having Î¦ = 120Â° and Î¨ = 30Â°. After ECAP processing, significant grain refinement and increase in the hardness was observed. Compression test was used to determine the flow properties of ECAP processed samples. Force-stroke data was recorded from the compression test. Flow curves were drawn by using force-stroke data. Strength coefficient and strain-hardening exponent were determined from the log-log plot of true stress-strain curves. Significant increase in the strength coefficient was observed after ECAP processing. Also, the strength coefficient is increased when the zinc content is increased in the alloy. Strain-hardening exponent was decreased with increase in the number of ECAP passes. Â© Published under licence by IOP Publishing Ltd.
Microstructural characterization and mechanical properties of cast Al-15Zn-2Mg alloy subjected to severe plastic deformation
(2018) Manjunath, G.K.; Udaya, Bhat, K.; Preetham, Kumar, G.V.
In the present work, Al-15Zn-2Mg alloy was processed by ECAP technique for grain refinement. The ECAP processing was conducted at 150 �C. Microstructural characterization was carried out in OM, SEM, TEM and XRD. To evaluate the mechanical properties, hardness measurement and tensile tests were conducted at room temperature. Microstructural characterization showed that, ECAP processing leads to decrease in the grain size of the alloy. Also, small amount of dislocations were also observed in the ECAP processed material. After ECAP processing, precipitates nucleation in the material was identified in the XRD analysis. The strength and the hardness values were increased after ECAP processing. After ECAP processing, microhardness of the material is increased from 173 Hv to 252 Hv and the UTS of the material is increased from 166 MPa to 362 MPa. After tensile testing, fracture surface of the cast material showed dendritic structure and the fracture surface of the ECAP processed material showed dimples. � 2018 Elsevier Ltd. All rights reserved.
Microstructural characterization and mechanical properties of cast Al-15Zn-2Mg alloy subjected to severe plastic deformation
(Elsevier Ltd, 2018) Manjunath, G.K.; Udaya Bhat, K.; Preetham Kumar, G.V.
In the present work, Al-15Zn-2Mg alloy was processed by ECAP technique for grain refinement. The ECAP processing was conducted at 150 Â°C. Microstructural characterization was carried out in OM, SEM, TEM and XRD. To evaluate the mechanical properties, hardness measurement and tensile tests were conducted at room temperature. Microstructural characterization showed that, ECAP processing leads to decrease in the grain size of the alloy. Also, small amount of dislocations were also observed in the ECAP processed material. After ECAP processing, precipitates nucleation in the material was identified in the XRD analysis. The strength and the hardness values were increased after ECAP processing. After ECAP processing, microhardness of the material is increased from 173 Hv to 252 Hv and the UTS of the material is increased from 166 MPa to 362 MPa. After tensile testing, fracture surface of the cast material showed dendritic structure and the fracture surface of the ECAP processed material showed dimples. Â© 2018 Elsevier Ltd. All rights reserved.
Microstructure and Mechanical Properties of Cast Al-5Zn-2Mg Alloy Subjected to Equal-Channel Angular Pressing
(Springer New York LLC barbara.b.bertram@gsk.com, 2018) Manjunath, G.K.; Preetham Kumar, G.V.P.; Udaya Bhat, K.; Huilgol, P.
In the present work, cast Al-5Zn-2Mg alloy was processed through equal-channel angular pressing (ECAP) in route BC up to four number of passes. Microstructure and mechanical properties were investigated on processed and unprocessed materials. In cast condition, the material was composed of dendritic structure. After homogenization treatment, large-sized grains were observed. After ECAP processing, significant grain refinement was observed. After ECAP processing, high-density dislocations and high degree of misorientation between the grains were observed. In cast material, rod-shaped precipitates were observed, while, after ECAP processing, spherical-shaped precipitates were observed. ECAP processing leads to a noticeable improvement in the mechanical properties of the material. After four passes, 122% improvement in the microhardness and 135% improvement in the ultimate tensile strength of the material were observed. After three passes, a slight decrease in the mechanical properties was observed. This is attributed to the dissolution of the metastable ?? phase, annihilation of dislocations, dynamic recrystallization and texturing during ECAP processing. Brittle fracture mode was observed in tensile testing cast and homogenized samples. After ECAP processing, fracture mode was changed into shear fracture mode. © 2018, ASM International.
Microstructure and Wear Performance of ECAP Processed Cast Al–Zn–Mg Alloys
(Springer, 2018) Manjunath, G.K.; Udaya Bhat, K.; Preetham Kumar, G.V.; Ramesh, M.R.
In the present investigation, wear performance of equal channel angular pressing (ECAP) processed cast Al–Zn–Mg alloys under dry sliding wear conditions was studied against a steel disc. Initially, Al–Zn–Mg alloys (with 5, 10, 15% zinc and 2% magnesium) were ECAP processed. After ECAP, grain size was reduced and enhancement in the hardness was observed. Wear resistance of the alloys increased after ECAP processing. Wear resistance of the alloys also increased when the quantity of the zinc was increased in the alloys. But, wear resistance of all three alloys decreased with increase in the load and the sliding speed. Coefficient of friction of the alloys decreased after ECAP processing. Coefficient of friction of the alloys also decreased when the quantity of the zinc was increased in the alloys. Coefficient of friction of all three alloys increased with increase in the load and the sliding speed. Irrespective of the alloy composition and applied load, worn surfaces of the cast and homogenized samples were composed of plastic deformation, scratches and micro-ploughing. On the other hand, in ECAP processed samples, morphology of the worn surfaces depended on the applied load. Abrasive wear is the main wear mechanism perceived in cast and homogenized samples at all loads. While in ECAP processed samples, the wear mechanism shifted from adhesive and oxidation wear to abrasive wear with increase in the load. Formation of oxide layers on the surface of the sample increased with increase in the ECAP passes. In ECAP processed samples, transfer of iron content from the disc to the sample surface was identified. © 2018, The Indian Institute of Metals - IIM.
Microstructure Evolution in Cast Al-Zn-Mg Alloys Processed by Equal Channel Angular Pressing
(Springer New York LLC barbara.b.bertram@gsk.com, 2018) Manjunath, G.K.; Udaya Bhat, K.; Preetham Kumar, G.V.
In the present work, microstructure development and enhancement in the microhardness of Al-Zn-Mg alloys (with 5, 10, and 15% zinc) during equal channel angular pressing (ECAP) were investigated. Dendritic morphology was observed in the cast condition of all three alloys, and precipitates were situated along the inter-dendritic regions. After homogenization, precipitates in the inter-dendritic regions were uniformly distributed in the aluminum matrix and grain boundaries were developed. After 4 passes in route BC, large reduction in the grain size was observed. X-ray diffractometry showed that MgZn2 precipitate was developed in the ECAP-processed samples. Increase in the intensity of MgZn2 peaks was observed when the quantity of zinc is increased in the material. Also, changes in the intensity of XRD peaks were observed in ECAP-processed samples due to shear deformation. After ECAP, substantial increase in the microhardness was perceived. After four passes, microhardness increased to 109, 67, and 58% from the initial condition in A1, A2, and A3 alloys, respectively. Also, improvement in the microhardness was also observed when the quantity of zinc is increased in the material. © 2017, Springer Science+Business Media, LLC, part of Springer Nature and ASM International.
Precipitate evolution during severe plastic deformation of cast Al-Zn-Mg alloys and their thermal stability
(Institute of Physics Publishing helen.craven@iop.org, 2019) Manjunath, G.K.; Huilgol, P.; Preetham Kumar, G.V.P.; Bhat, K.U.
In the current investigation, an effort was made to understand the precipitate evolution process during equal channel angular pressing (ECAP) of an alloy composed of only aluminium, zinc and magnesium. For this purpose, three different compositions of cast Al-Zn-Mg alloys were selected and ECAP processed in route BC upto four passes. Microstructural observations indicated that, ECAP processing leads to refined structure possessing high density dislocations and large amount of grains with high angle grain boundaries. The precipitate volume in the alloys increased with increase in the zinc quantity in the alloy. Microstructural characterization through transmission electron microscope (TEM) and differential scanning calorimeter (DSC) revealed that, processing by ECAP results in structure having stable ? phase precipitates without the presence of GP zones and intermediate ?? phase precipitates. Thereby demonstrates that, ECAP process accelerates the precipitation kinetics and also shifts the morphology of the precipitates. Higher mechanical properties were noticed in the alloy containing large quantity of MgZn2 precipitates. © 2018 IOP Publishing Ltd.
Severe plastic deformation of Al-15Zn-2Mg alloy: Effect on wear properties
(2019) Manjunath, G.K.; Bhat, K.U.; Kumar, G.V.P.
In the present work, Al-Zn-Mg alloy having highest zinc content was deformed by one of the severe plastic deformation (SPD) technique, equal channel angular pressing (ECAP) and effect of ECAP on the microstructure evolution and the wear properties were studied. ECAP was performed in a split die and the channels of the die are intersecting at an angle of 120�. ECAP was attempted at least possible temperature and the alloy was successfully ECAPed at 423 K. Below this temperature samples were failed in the first pass itself. After ECAP, significant drop in the grain size was reported. Also, ECAP leads to significant raise in the microhardness of the alloy. Predominantly, after ECAP, upsurge in the wear resistance of the alloy was noticed. To figure out the response of ECAP on the wear properties of the alloy; worn surfaces of the wear test samples were analyzed in SEM. � 2019 Trans Tech Publications Ltd, Switzerland.
Severe plastic deformation of Al-15Zn-2Mg alloy: Effect on wear properties
(Trans Tech Publications Ltd ttp@transtec.ch, 2019) Manjunath, G.K.; Bhat, K.U.; Preetham Kumar, G.V.
In the present work, Al-Zn-Mg alloy having highest zinc content was deformed by one of the severe plastic deformation (SPD) technique, equal channel angular pressing (ECAP) and effect of ECAP on the microstructure evolution and the wear properties were studied. ECAP was performed in a split die and the channels of the die are intersecting at an angle of 120Â°. ECAP was attempted at least possible temperature and the alloy was successfully ECAPed at 423 K. Below this temperature samples were failed in the first pass itself. After ECAP, significant drop in the grain size was reported. Also, ECAP leads to significant raise in the microhardness of the alloy. Predominantly, after ECAP, upsurge in the wear resistance of the alloy was noticed. To figure out the response of ECAP on the wear properties of the alloy; worn surfaces of the wear test samples were analyzed in SEM. Â© 2019 Trans Tech Publications Ltd, Switzerland.
Tensile Properties and Tensile Fracture Characteristics of Cast Al–Zn–Mg Alloys Processed by Equal Channel Angular Pressing
(Springer India sanjiv.goswami@springer.co.in, 2017) Manjunath, G.K.; Preetham Kumar, G.V.; Bhat, K.U.
In the present work, as-cast Al–5Zn–2Mg, Al–10Zn–2Mg and Al–15Zn–2Mg alloys were ECAP processed and tensile tests were carried out to determine the strength and ductility. After tensile testing, morphology of the fracture surfaces of tensile tested samples were studied. After ECAP processing, significant improvement in the yield stress and ultimate tensile strength were observed in all the three alloys. Also, yield stress and ultimate tensile strength were increased with increase in the zinc content of the material. The elongation to failure increased significantly with increase in the number of ECAP passes. SEM micrographs revealed that, the fracture surface of the cast samples of the alloys were composed of the dendritic structure, while the ECAP processed samples consisted of small size dimples. Size of the dimples were reduced with the increase in the number of ECAP passes. © 2017, The Indian Institute of Metals - IIM.
Tensile toughness characteristics of cast Al-Zn-Mg alloys processed by equal channel angular pressing
(2020) Manjunath, G.K.; Bhat, K.U.; Preetham, Kumar, G.V.
In the current study, consequence of ECAP on the toughness characteristics of the Al-Zn-Mg alloys was studied. Three set of Al-Zn-Mg alloys (5, 10 and 15% Zn and 2% Mg) were selected and ECAPed. Also, consequence of zinc on the toughness characteristics of the alloy, before and after ECAP was studied. After ECAP, grain size of the alloys decreased and significant rise in the strength and ductility of the alloys were noticed. Mainly, modulus of toughness of the alloys increased with successive ECAP passes. But, the modulus of toughness of the alloys decreased with rise in the zinc in the material. � 2020 Trans Tech Publications Ltd, Switzerland.
Tensile toughness characteristics of cast Al-Zn-Mg alloys processed by equal channel angular pressing
(Trans Tech Publications Ltd ttp@transtec.ch, 2020) Manjunath, G.K.; Bhat, K.U.; Preetham Kumar, G.V.
In the current study, consequence of ECAP on the toughness characteristics of the Al-Zn-Mg alloys was studied. Three set of Al-Zn-Mg alloys (5, 10 and 15% Zn and 2% Mg) were selected and ECAPed. Also, consequence of zinc on the toughness characteristics of the alloy, before and after ECAP was studied. After ECAP, grain size of the alloys decreased and significant rise in the strength and ductility of the alloys were noticed. Mainly, modulus of toughness of the alloys increased with successive ECAP passes. But, the modulus of toughness of the alloys decreased with rise in the zinc in the material. Â© 2020 Trans Tech Publications Ltd, Switzerland.