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    Abrasive Wear Behavior of Nano-Sized Steel Scale on Soft CuZn35Ni2 Material
    (Springer, 2023) Demirsoz, Recep; Ugur, Abdullah; Erdogdu, Ahmet Emrah; Korkmaz, Mehmet Erdi; Gupta, Munish Kumar
    This study examines the abrasive wear behavior of nano-sized steel scale on the CuZn35Ni2 Soft material. CuZn35Ni2 Soft material was used as a sample, and the three-body wear mechanism formed by nanoscale particles mixed with lubricating oil was investigated using a ball-on-flat tester. Three different loads, three different sliding speeds and three different environment variables were used in the experiments. A lubricant containing 0.15 and 0.3 wt.% nanoscale and a non-abrasive lubricant was used to form the medium. The experimental results were obtained as mass loss, wear depth and friction coefficient and the wear surfaces were examined using scanning electron microscopy/energy-dispersive x-ray spectroscopy (SEM/EDX). The analysis of variance method was used to determine the effect of independent variables on the results. As a result of the study, it was concluded that the most effective parameter for mass loss and CoF was the environment, and the most effective parameter for the depth of wear was the load. It was concluded that there might be a difference of up to 10% in the coefficient of friction between the experiments and the predicted values. Still, in general, the predicted values and the experimental results agree.
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    Development of Forming Temperature Curves for Warm Deep Drawing Process Under Non-isothermal Conditions
    (Springer Heidelberg, 2015) Cetin, M. Huseyin; Ugur, Abdullah; Yigit, Osman; Gokkaya, Hasan; Arcaklioglu, Erol
    Temperature is the main effective process parameter in the warm deep drawing (WDD) process to improve the formability of light-weight engineering materials, and this feature requires the accurate measurement and assessment of temperature for process stability. In this study, an evaluation of the WDD process was conducted according to the forming temperature curves (FTCs) characterized from work piece temperatures instead of tool temperatures, as usual. To achieve this goal, a special index material was developed to accurately obtain FTCs from the work piece material under closed and heated tool conditions. The differences of temperature on work piece material are required to define temperatures by curves. The characteristic behavior of these curves was investigated under non-isothermal WDD of AA 5754-O. In the experimentation stage, the process parameters, namely FTC, blank holder force and punch velocity, which assure successful deep drawability, were determined according to the failure-free cups by analyzing wrinkling and tearing conditions and minimum cup height parameters as output parameters. As the next step, optimum conditions were investigated by evaluating the cup volume and spring-back parameters. As a general conclusion, approximately 330A degrees C in the flange-die radius region and 100A degrees C in the cup wall-punch bottom region are the ideal optimum temperatures for the warm deep drawing process.
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    INVESTIGATION OF ELECTROEROSION MACHINING PERFORMANCE OF METAL MATRIX COMPOSITE MATERIALS PRODUCED USING STIR AND INDIRECT SQUEEZE METHOD
    (World Scientific Publ Co Pte Ltd, 2023) Ugur, Abdullah; Nas, Engin; Gokkaya, Hasan
    In this study, metal matrix composite (MMC) materials were made with an aluminum matrix (AA7075 alloy) and reinforcement silicon carbide (SiC) elements using molten metal stir and indirect squeeze casting. SiC was used as a reinforcing element in the making of MMC material in different amounts (10%, 14%, and 18%) by mass. Electro Discharge Machining (EDM), cut depth (0.5 mm), three different pulse-on times, three different discharge current values, and a fixed pulse-off time (20 s) were used to machine MMC materials. The effects of machining parameters on machining time, average surface roughness, hole diameter, and material wear difference after machining were studied. As a result of the study, the composite material with 75 mu s pulse-on time, 6A current value, and 10% reinforcement element had the lowest machining time, the largest hole diameter, and the smoothest average surface. These machining parameters and materials also had the shortest machining time (5 min). Based on the signal-to-noise ratios, the best parameters for average surface roughness, hole diameter, Processing time, and material wear amount (MMC, discharge current value, and impact time) were found to be L2L1L1, L3L1L1, L1L3L3, and L1L1L2, respectively. Based on the ANOVA results, the R2 values for the average surface roughness, hole diameter, machining time, and material wear loss value were 99.3%, 98.7%, 77.8%, and 97.3%, respectively.
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    Investigation of the machinability of SiC reinforced MMC materials produced by molten metal stirring and conventional casting technique in die-sinking electrical discharge machine
    (Pergamon-Elsevier Science Ltd, 2020) Ugur, Abdullah; Nas, Engin; Gokkaya, Hasan
    In this study, MMC materials were produced by stir casting method using AA7075 alloy matrix and silicon carbide (SiC) as reinforcement elements in order to investigate the effect of die-sinking electric discharge machining (EDM) process parameters for various weight percentage reinforcement (10% 14% and 18%) used MMC. EDM with three different pulse-on time (Time on) (25, 50 &75 mu s) and discharge current value (2, 4 & 6 Amperes) and at constant dwell time (20 mu s) and depth of cut (0.5 mm). After machining process, the effects of process parameters on processing time, average surface roughness, hole diameter and the weight loss were investigated. As a result of the study, highest values, the lowest values of processing time, hole diameter and average surface roughness were obtained for various weight percentage reinforcement MMC respectively. Ideal MMC, discharge current value and time-on duration for average surface roughness, hole diameter, processing time and material wear loss according to signal to noise ratio were determined. According to ANOVA results, R-2 values for the average surface roughness, hole diameter, processing time and material wear loss were calculated as 89.55%, 98.46%, 89.85% and 24.06% respectively.
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    Understanding the slurry erosion behaviour of iron-based chromium carbide coating material during deposition via arc spray coating method
    (Sage Publications Ltd, 2023) Demirsoz, Recep; Singla, Anil Kumar; Ugur, Abdullah; Erdogdu, Ahmet Emrah; Korkmaz, Mehmet Erdi; Gupta, Munish Kumar; Krolczyk, Jolanta Beata
    The material S235JR was spray-coated with iron-based chromium carbide in the present study. The effects of the initial surface roughness on slurry erosion were investigated. Samples with a rough surface and polished surface were used. The impact of particle concentration, impact velocity and impact angle was studied on the slurry erosion characteristics in terms of mass loss, surface roughness and surface temperature. In addition, the surfaces were analysed using a scanning electron microscope (SEM). Further, the estimation equation has been derived using response surface method (RSM) based on the data obtained in the study. The results show that velocity and concentration are the key factors in determining the mass loss and surface temperature while the impact angle has a relatively minor role. Mass losses in rough samples ranged from 8.8 mg to 40 mg; in polished samples, the range ranged from 5.6 mg to 10.9 mg.