Browsing by Author "Irizalp S.G."

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    Investigation of wear behaviour of thixoformed and conventional gravity cast AlSi8Cu3Fe alloys
    (2014) Saklakoglu N.; Irizalp S.G.; Ercayhan Y.; Birol Y.
    Purpose-In the present work, thixoformed AlSi8Cu3Fe alloy was investigated for its tribological properties. The tribological analysis reveals good sliding wear behaviour for thixoformed alloy due to thixotropic microstructural character. The results are compared with sliding wear behaviour of conventional gravity cast alloy. This paper aims to discuss these subjects. Design/methodology/approach-In this study, thixoforming and gravity casting methods are used to produce materials. The ball-on-disc CSM tribometer was used to carry out the tribological tests that were performed under dry sliding conditions, under two different loads of 1N and 5N. Wear tests were performed first on the conventional gravity cast samples and then on the thixoformed counterparts in exactly the same fashion to facilitate a comparison. The microstructural characterizations are performed in optical microscopy, scanning electron microscopy and energy dispersive X-ray spectrometry. Findings-Thixoformed samples have better wear resistance than conventional gravity cast samples. The wear performance improves in thixoformed AlSi8Cu3Fe alloy thanks to changing the microstructure. The superiority of the former is attributed to its structural features. Originality/value-In this study, the thixoforming of AlSi8Cu3Fe alloy can provide important wear performance in comparison with conventional casting of AlSi8Cu3Fe alloy. This alloy is known to be used widely in automotive industry. Therefore, the alloy is highly exposed to wear and it is thought that thixoforming method can increase the wear resistant. © Emerald Group Publishing Limited.
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    Wear behavior of Al/SiC/graphite and Al/FeB/graphite hybrid composites
    (Institute of Metals Technology, 2014) Şahin S.; Yüksel N.; Durmuş H.; Irizalp S.G.
    Silicon carbide is often the preferred reinforcement in the production of aluminium-powder composites. In this study, aluminium composites were produced with 10 % and 20 % silicon-carbide and ferroboron reinforcements and (0, 0.5, 1 and 1.5) % graphite additions using powder metallurgy. The effects of the reinforcement type, the amount and the graphite content on the wear resistance were investigated. When compared with the unreinforced aluminium sample, it was clear that the increasing reinforcement increased the wear resistance. It was determined that the increasing graphite content negatively affects the wear resistance. The sample including 20 % ferroboron and 0 % graphite showed the minimum wear rate.
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    Laser shock processing of 6061-T6 aluminium alloy: Thermal modelling and analysis
    (Old City Publishing, 2016) Zafar H.; Saklakoglu N.; Irizalp S.G.; Khan S.; Shuja S.Z.; Boran K.; Yilbas B.S.
    Laser shock processing of 6061-T6 aluminium alloy is carried out. Temperature and stress fields are simulated in line with the experimental conditions. Metallurgical changes due to the laser shock and microhardness in the laser treated region are examined using analytical tools that include scanning and transmission electron microscopes and microhardness tester. The depth of shock affected region, plastic strain, and dislocation density are determined numerically and experimentally in the laser treated region. It is found that the temperature attains high values at the centre of the irradiated spot resulting in high rate of evaporation at the surface. The recoil pressure formed, due to high evaporation rate, at the laser treated surface results in plastic deformation of about 500 mm below the surface. A dislocation density of the order 2 × 1013 to 4 × 1013 cm-2 occurs in the surface region. Although high temperature gradients result in high stress levels in the region below the surface vicinity, high recoil pressure results in crack free surface with compressive stress. © 2016 Old City Publishing, Inc.
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    Performance of Fe-based hardfacings on hot forging die: Experimental, numerical and industrial studies
    (Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, 2018) Saklakoglu N.; Irizalp S.G.; Dogan S.; Ildas G.; Saklakoglu I.E.
    This paper is an investigation into the use of Fe-based alloys as part of wear resistant hardfacing materials in AISI 1.2714 tool steel. Four different weld hardfacing alloys were deposited on 1.2714 steel substrates using tungsten inert gas welding (TIG) process. Wear tests were carried out using a pin-on-disc wear tester at room temperature. Microhardness and micrographs of the weld overlays were obtained. High-Temperature properties were estimated by numerical analysis. The phases of the hardfacings were obtained by XRD and also estimated by numerical analysis. The results from the laboratory tests were then compared with the results obtained from field studies. The results showed that some Fe-based alloys improved dies lifetime; others created poor surfaces. A Fe-based hardfacing alloy D which included high C with Cr, W, Mo had the best wear behavior among the weld overlays. © 2018 Institute of Materials and Machine Mechanics, Slovak Academy of Sciences. All rights reserved.
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    Performance of Fe-based hardfacings on hot forging die: Experimental, numerical and industrial studies
    (Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, 2018) Saklakoglu N.; Irizalp S.G.; Dogan S.; Ildas G.; Saklakoglu I.E.
    This paper is an investigation into the use of Fe-based alloys as part of wear resistant hardfacing materials in AISI 1.2714 tool steel. Four different weld hardfacing alloys were deposited on 1.2714 steel substrates using tungsten inert gas welding (TIG) process. Wear tests were carried out using a pin-on-disc wear tester at room temperature. Microhardness and micrographs of the weld overlays were obtained. High-temperature properties were estimated by numerical analysis. The phases of the hardfacings were obtained by XRD and also estimated by numerical analysis. The results from the laboratory tests were then compared with the results obtained from field studies. The results showed that some Fe-based alloys improved dies lifetime; others created poor surfaces. A Fe-based hardfacing alloy D which included high C with Cr, W, Mo had the best wear behavior among the weld overlays. © 2018 Institute of Materials and Machine Mechanics, Slovak Academy of Sciences. All rights reserved.
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    Effects of shot peening and artificial surface defects on fatigue properties of 50CrV4 steel
    (Springer Science and Business Media Deutschland GmbH, 2021) Saklakoglu N.; Bolouri A.; Irizalp S.G.; Baris F.; Elmas A.
    Shot peening processes are commonly used for improving the fatigue properties of steels. Shot peening introduces a compressive residual stress field in the near surface of steel, which can reduce or stop the growth of fatigue cracks and improve fatigue properties. This study experimentally investigated the effect of shot peening on the fatigue properties of 50CrV4 steel alloys with different artificial surface defects. Drilling tools were used to introduce different artificial defects with root radii of 0.585 mm and 0.895 mm on the surface of unpeened samples. The shot peening was applied to the drilled and undrilled samples. Scanning electron microscopy (SEM) observations, micro-hardness and X-ray diffraction residual stress measurements were conducted to analyse the characteristics of the shot-peened and unpeened samples. The results show that the shot peening leads to the transformation of the retained austenite to martensite in the near-surface microstructure. The hardness rates of the surface and near surface both increase by 8% after the shot peening. The peened samples exhibit compressive residual stresses with a high degree of isotropy in the near surface. The fatigue properties of samples were experimentally evaluated by conducting 3-point bending tests. The results indicate that the shot peening improves the fatigue life of drilled and undrilled samples. For the defects with the root radius of 0.895 mm, the shot peening leads to a 500% improvement in the fatigue life compared to unpeened samples regardless of defect depth. For the defects with the root radius of 0.585 mm, the improvement in fatigue life is 40% for the defect depth of 0.2 mm compared to unpeened samples. The improvement increases to 60% and 200% by increasing the defect depths to 0.4 mm and 0.6 mm. The fatigue properties are linked to the changes in the features of defects mainly caused by the deformation hardening and compressive residual stress after shot peening. © 2021, The Author(s).
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    Study on surface and mechanical properties of stainless steel plates with multiple shot peening and laser peening without coating
    (Taylor and Francis Ltd., 2024) Irizalp S.G.; Koroglu B.K.; Mutlu O.
    This article compares the effects of single and multiple SP treatments, as well as LPC and LPWC treatments, on the surface and mechanical properties of 304SS. Experimental data were generated to compare the surface conditions, microhardness, and tensile properties. The surface roughness of multiple SP and LPC treatments was similar and relatively low. The microhardness layer could be obtained 100% deeper in LP-treated samples than in SP-treated samples. The maximum microhardness reached on the surface of SP-treated samples is 30% higher than that of LP-treated samples. Tensile test results showed an almost 50% increase in strength for LPWC and multiple SP treatments. X-ray phase analysis revealed that a more intense α’-martensite phase was formed in triple SP treatments compared to single SP treatments. The analysis also revealed the formation of low amounts of α’-martensite due to local melting in both LPC and LPWC samples, with a reported broadening of the austenite peaks. Additionally, the work hardening effect likely offsets the detrimental surface conditions after SP and LPWC treatments, showing that multiple SP and LPWC surface treatments have beneficial effects in terms of mechanical and metallurgical properties. It has been revealed that LPWC exhibits better mechanical properties than LPC, and multiple SP treatments have better mechanical properties than single SP treatments. © 2024 Informa UK Limited, trading as Taylor & Francis Group.