Sürdürülebilir Kalkınma Amaçları

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• MakaleYalnız künye2025/r/gumushane/19645
  Effect of Chromium Addition on ZA40 Alloy Fabricated by Powder Metallurgy Method

  Aydin, Kemal

  The aim of this study is to develop and investigate the properties of chromium powder-reinforced metal-metal composites using powder metallurgy methods with a ZA40 alloy matrix. To analyze the effect of varying chromium particle amounts on ZA40-Cr composites, samples with chromium weight percentages of 5%, 10%, and 15% were produced. To ensure uniform distribution of chromium particles, the matrix and composite powders were mixed in ball mills for five hours. These powders were then hot-pressed under an argon gas atmosphere at 500°C and 500 MPa pressure for two hours to form the samples. The samples were evaluated by determining the microstructure, hardness, density, and tensile properties of the ZA40-Cr metal-metal composites with varying chromium content. Porosity and relative density results revealed that increasing Cr content increased porosity while reducing relative density. Hardness measurements showed that the sample with 10% Cr addition exhibited the highest hardness value (182 Brinell). However, increased porosity in the 15% Cr sample caused a decline in hardness. Tensile strength tests indicated that the sample with 10% Cr addition achieved the highest strength (240 MPa). The results demonstrated that the reinforcement of the ZA40 matrix with Cr particles at specific ratios enhanced the mechanical performance, but that excessive Cr content adversely affected the properties due to increased porosity. The optimum Cr content was determined to be 10%, providing the best mechanical properties. This study highlights the potential of ZA40-Cr composites as cost-effective and high-performance materials for engineering applications.

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  İncele
• MakaleYalnız künye2025/r/gumushane/14118
  Optimization of steel diffusion bonding processes using the Taguchi method

  Serkan Yıldırım, Mehmet; Aydın, Kemal; Kalyon, Ali; Kaya, Yakup

  This study examines the diffusion bonding behavior between 316L stainless steel and H13 tool steel, focusing on the effects of key process parameters. Specifically, the influence of bonding pressure, bonding temperature, and holding time on joint quality and mechanical performance is systematically investigated. The Taguchi optimization method was employed to determine the optimal bonding conditions, with shear strength serving as the primary performance indicator. The bonding interfaces were characterized through scanning electron microscopy to analyze microstructural evolution and diffusion behavior. Analysis of variance was conducted to assess the influence of process parameters on shear strength, identifying temperature as the most significant factor. The optimum shear strength was experimentally validated, and a confidence interval was calculated to ensure statistical reliability. The results demonstrated that higher bonding temperatures and moderate pressures led to improved diffusion at the interface, enhancing joint integrity. The findings contribute to a better understanding of the diffusion bonding process and its potential for high-performance applications in aerospace, biomedical, and tooling industries.

  İncele
• MakaleYalnız künye2025/r/gumushane/14112
  The effect of welding parameters on weld bead geometry in gas tungsten arc welding applications by response surface methodology model

  Yildirim, Mehmet Serkan; Ayhan, Emre; Aydin, Kemal; Durgutlu, Ahmet

  This study examines the effects of tungsten electrode sharpening angle, torch angle, and arc length on weld bead geometry in gas tungsten arc welding (GTAW). Low-carbon steel plates (4 mm thickness) were welded using ER70S-6 filler wires (2 mm diameter). Experimental analyses and response surface methodology (RSM) revealed that increasing the electrode sharpening angle enhances penetration depth, while reducing the torch angle widens the bead. Longer arc lengths decrease penetration but increase bead width. Validation tests confirmed the accuracy of the RSM models, showing an average deviation of 1.14%. Analysis of variance highlighted the statistical significance of linear, quadratic, and interaction terms in the models. The findings provide critical insights for optimizing GTAW parameters, improving weld quality, and advancing process control, thereby contributing both practical and academic value to welding research.

  İncele
• MakaleAçık Erişim2025/r/gumushane/12436
  Effects of Temperature and Time on the Diffusion Bonding of 316L Stainless Steel and H13 Hot Work Tool Steel

  Aydın, Kemal; Yıldırım, Mehmet Serkan; Kaya, Yakup

  This study examines the diffusion bonding of 316 L stainless steel and H13 hot work tool steel, aiming to optimize process parameters and assess the resulting microstructural and mechanical properties. Both materials were bonded at varying temperatures (700, 750, and 850 °C) and times (15, 30, and 60 min). The joints are analyzed using scanning electron microscopy (SEM), energy-dispersive spectroscopy, and X-ray diffraction (XRD) to evaluate interfacial morphology, chemical composition, and phase formation. Microhardness measurements indicate an increase in hardness from the 316 L side to the H13 side, suggesting intermetallic phase formation. Shear strength tests show the highest strength at 850 °C for 30 min, with longer times leading to strength reduction due to brittle intermetallic compounds. SEM analysis reveals improved bonding interfaces with fewer voids at higher temperatures and longer times, but the Kirkendall effect causes void formation, negatively impacting mechanical properties. XRD confirms α-Fe and γ-Ni phases, with Fe3C forming at 850 °C for 60 min. This study underscores the importance of process parameters in optimizing joint properties and minimizing brittle phase formation, providing insights for industrial applications requiring robust and corrosion-resistant joints.

  İncele
• MakaleAçık Erişim2024/r/gumushane/11725
  Optimizing Advanced High-Strength Steel Joints via Regional Rapid Cooling in Resistance Spot Welding

  Hıdıroglu, Mehtap; Aydın, Kemal; Kahraman, Nizamettin

  During resistance spot welding (RSW), the thermal cycles that occur cause microstructural differentiations in the heat-affected zones of martensitic steels, leading to internal stresses. In this context, a new and innovative methodology has been developed to minimize the adverse effects of heterogeneous hardness changes in the welding area on joint durability. This methodology utilizes a unique prototype setup based on the regional rapid cooling (RRC) process, which is integrated into the welding machine and operates in synchronization with the machine during the process. Through this setup, the aim is to effectively control the microstructure and hardness values in the welding area. This innovative approach presents potential improvements in the field of welding technology by aiming to optimize material performance during the welding process. According to microstructure results, the RRC process has narrowed the heat-affected zone to 1.27 mm, increased the hardness values by 9.2%, showed a 3% increase in tensile-shear strength, a 9% increase in cross-tension strength, and based on fatigue strength results, no fractures occurred in all specimens subjected to a force of 0.3 kN.

  İncele
• MakaleYalnız künye2022/r/gumushane/12816
  Characterization of the Welding Zone of Automotive Sheets of Different Thickness (DP600 and DP800) Joined by Resistance Spot Welding

  Aydin, Kemal; Hidiroglu, Mehtap; Kahraman, Nizamettin

  Automotive industry in recent years, has gained great importance. In line with this, DP600 and DP800 dual-phase steels and the electrical resistance spot welding method were used in the study. During the experimental trials, different welding currents (6, 7, and 8 kA) were selected and all other welding parameters were kept constant. The effects of the welding parameters on microstructure, hardness, tensile-shear, and cross-tensile strength were analyzed. In the phase measurements, 27.06–29.97% martensite and 70.73–73.85% ferrite phases were found. When the hardness values in the HAZ regions were examined, it was seen that the highest hardness values were 356 ± 5 HV in the DP600 and 451 ± 5 HV in the DP800 with a current intensity of 6 kA. Consequently, it was determined that tensile-shear and cross-tensile strengths had increased in parallel with the increase in the welding current and the highest values were determined as 8 kA–15.91 kN in tensile shear and 8 kA–4.91 kN in cross-tensile strength.

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