Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    Laser Surface Treatment Optimization of 1.2379 (Aisi D2) Tool Steel
    (Springernature, 2025) Ozbey, Sayit; Artem, Hatice Secil
    Industrial applications require materials with specific surface quality and hardness properties. Laser surface treatment stands out as a cost-effective and effective method that improves surface performance by changing the structural and physical properties of the material. 1.2379 cold work tool steel is a commonly used material in die and mold industries for injection mold inserts; therefore, the surface properties of the material play a significant role. In this study, it is aimed to optimize laser parameters; the laser power, pulse duration, repetition rate and line spacing for the responses such as hardness and surface roughness. For this purpose, 1.2379 cold work tool surfaces were treated using a commercially available industrial ytterbium low-power pulsed fiber laser experimentally. Experiments were conducted based on 34 full factorials. Vickers hardness and micro-roughness measurements were performed on the laser-treated surfaces. Regression models were developed using experimental data and the appropriate models were selected for each response. The response variables were then optimized based on stochastic optimization methods: Nelder-Mead, Differential Evolution, Random Search and Simulated Annealing. The results indicate that a maximum hardness of 495 HV0.5 and a minimum surface roughness of 0.277 mu m were achieved, corresponding to a 61% increase and a 43% decrease, respectively, compared to the base metal.
  • Article
    Citation - WoS: 8
    Citation - Scopus: 8
    Comparing Compression Deformation and Rate Sensitivity of Additively Manufactured and Extruded-Annealed 316l Alloys
    (Springer, 2021) Enser, Samed; Yavaş, Hakan; Arslan Hamat, Burcu; Aydın, Hüseyin; Kafadar, Gülten; Tanrıkulu, A. Alptuğ; Zeytin Kazdal, Havva; Öztürk, Fahrettin; Güden, Mustafa
    The deformation behavior of a selective-laser-melt-processed 316-L alloy (SLM-316L) under compression was determined together with a commercial annealed-extruded 316L alloy bar (C-316L) for comparison. Strain rate jump tests and hardness tests on the untested and compression tested samples were also performed. Extensive microscopic observations on the deformed and undeformed samples showed a twinning-dominated deformation in SLM-316L, similar to twinning-induced-plasticity steels, while a martensitic transformation-dominated deformation in C-316L alloy, similar to transformation-induced-plasticity steels. Within the studied quasi-static strain rate regime, the measured higher strain rate sensitivity of SLM-316L was ascribed to the lower distances between the nano-twins, in the level of 100 nm, than the distances between martensite plates, in the level of 1000 nm. A higher hardness increase in the martensite transformation region as compared with the twinned region proved the higher work hardening of C-316L. The hardness tests in the micron and sub-micron levels further confirmed the previously determined relatively low resistances of the dislocation cell walls (sub-grain) to the dislocation motion in SLM-316L alloy.
  • Article
    Citation - WoS: 17
    Citation - Scopus: 26
    Thixoforming of A356/Sic and A356/Tib2 Nanocomposites Fabricated by a Combination of Green Compact Nanoparticle Incorporation and Ultrasonic Treatment of the Melted Compact
    (Springer Verlag, 2014) Kandemir, Sinan; Atkinson, Helen V.; Weston, David P.; Hainsworth, Sarah V.
    Thixoforming is a type of semi-solid processing which is based on forming metals in the semi-solid state rather than fully liquid or solid state. There have been no reports of the thixoforming of nanocomposites in the literature. The incorporation of ceramic nanoparticles into liquid metals is a challenging task for the fabrication of metal matrix nanocomposites due to their large surface-to-volume ratio and poor wettability. Previous research work by a number of workers has highlighted the challenges with the incorporation of nanoparticles into liquid aluminum alloy. In the present study, SiC and TiB2 nanoparticles with an average diameter between 20 and 30 nm were firstly incorporated into green compacts by a powder forming route, and then the compacts were melted and treated ultrasonically. The microstructural studies reveal that the engulfment and relatively effective distribution of the nanoparticles into the melt were achieved. The hardness was considerably improved with only 0.8 wt pct addition of the nanoparticles. The nanocomposites were successfully thixoformed at a solid fraction between 0.65 and 0.70. The microstructures, hardness, and tensile mechanical properties of the thixoformed nanocomposites were investigated and compared with those of the as-received A356 and thixoformed A356 alloys. The tensile properties of the thixoformed nanocomposites were significantly enhanced compared to thixoformed A356 alloy without reinforcement, indicating the strengthening effects of the nanoparticles.