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Author: search.filters.author.Preetham Kumar, G.V.Subject: search.filters.subject.Equal channel angular pressing

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    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 °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.
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    Tribological behaviour of aluminium-zinc-magnesium alloy processed by equal channel angular pressing
    (Elsevier Ltd, 2020) Manjunath, G.K.; Bhat, K.U.; Preetham Kumar, G.V.
    In the present work, tribological behaviour of the Al-5Zn-2 Mg alloy processed by equal channel angular pressing (ECAP) was studied. Initially, the alloy was prepared by die casting process. ECAP processing was carried out in a split die with an angle of 120° between two channels. ECAP processing was carried out at 150 °C in route BC upto four passes. After ECAP, noticeable decrease in the grain size was observed which leads to significant increase in the hardness and strength of the alloy. In homogenized condition, grain size of 180 mm was observed. While after four passes, grain size was reduced to 1-2 mm. After ECAP, the hardness and strength of the alloy was increased by 122% and 135%, respectively from the initial condition. Predominantly, after ECAP, noticeable decrease in the wear volume loss and coefficient friction of the material was observed. To understand the effect of ECAP on the tribological behaviour of the alloy; worn surfaces of the wear test samples were studied by using scanning electron microscope. © 2020 Elsevier Ltd. All rights reserved.
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    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.
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    Effect of grain refinement on material properties of Mg-8%Al-0.5%Zn alloy after the combined processes of multi-direction forging and equal channel angular pressing
    (Institute of Physics, 2019) Naik, G.M.; Anjan, B.N.; Narendranath, S.; S Satheesh Kumar, S.; Preetham Kumar, G.V.
    Establishing the novel microstructure is an effective method to accelerate the applications of magnesium and its alloys. In this work, an Mg-8%Al-0.5%Zn alloy (AZ80 Mg) with ultra-fine-grain (UFG) size of ?1.29 ?m was achieved by the combined processes of multi-directional forging (MDF) and equal channel angular pressing (ECAP). The achieved ultra-fine grain structure made the Mg alloy, owing to inclusive performance as the structural material. The AZ80 Mg alloy with MDF 6 pass followed by two pass ECAP has superior mechanical properties such as ultimate tensile strength (UTS) of 352 MPa and elongation of 11% when compared to as-received Mg alloy. Also, an unprocessed Mg alloy showed the corrosion rate of a 13.28 mm y?1, the corrosion rate of processed Mg alloy could be further decelerated through a change of microstructure obtained from combined processes of MDF and ECAP. This study outstandingly obtained a 94% reduction of corrosion rate after MDF-3P followed by an ECAP-2P (0.77 mm y?1) process compared to as-received Mg alloy. © 2019 IOP Publishing Ltd.