Browsing by Author "Sahin, Burak"

Now showing 1 - 4 of 4

Application of Gov (Flow Peening) Process to Improve Surface Quality of Ti-6al of Aerospace Material
(Inderscience Enterprises Ltd, 2023) Kalak, Murat; Sahin, Burak; Gov, Ibrahim; Dogan, Abdurrahman; Gov, Kursad
Ti-6Al-4V is a difficult-to-cut material with wide applications due to its superior mechanical features. Non-traditional surface treatment methods namely abrasive flow machining and shot peening are applied to obtain desired surface quality. GOV (flow peening) process having advantages of surface quality and strength improvement (compressive residual stress generation) of AFM and shot peening respectively was developed. In this paper, the effects of the GOV process parameters (number of cycles, steel ball size, and media ratio) on the material surfaces were investigated to evaluate surface roughness (R-a), material removal amount and white layer thickness. The surface roughness, R-a value was decreased from 2.17 mu m to 0.80 mu m. In addition, 4.4 mg of material corresponds to total amount of white layer was removed (verified by SEM images). GOV process can be used to improve surface quality by decreasing surface roughness and removing white layer without any excess chip removal.
Experimental Investigation of Hydration Temperature Variation in Reinforced Concrete Beam Construction Under Winter Conditions
(Elsevier - Division Reed Elsevier India Pvt Ltd, 2026) Gedik, Burak; Okuyucu, Dilek; Kazaz, Iker; Bingol, Ahmet Ferhat; Sahin, Muhammet; Sahin, Burak
This study investigates the early-age thermal behaviour and hydration process of large-scale reinforced concrete beams cast under both winter and summer conditions, with a focus on the influence of fresh concrete temperature, admixture use, and environmental factors. Temperature monitoring was conducted for a minimum of 72 h using embedded sensors, and special attention was given to winter concreting under natural atmospheric conditions. Two winter casting scenarios were defined: Winter-1, with ambient temperatures below -15 degrees C, and Winter-2, ranging between -15 degrees C and +5 degrees C. Results show that fresh concrete temperature is the dominant factor in initiating hydration, with admixtures alone proving insufficient at low temperatures. Solar exposure and daytime casting significantly improved hydration behaviour, especially when specimens were covered with greenhouse plastic. In contrast, night-time casting under sub-zero temperatures delayed hydration by several hours, particularly in unheated conditions. Summer specimens exhibited consistent hydration aligned with reference laboratory behaviour. The temperature-time factor development of the without admixture winter group specimens average decreased by 39 % after 48 h. The findings highlight the importance of controlling fresh concrete temperature and utilizing environmental aids in cold weather concreting.
Surface Strengthening of Aerospace Material of Inconel 718 by GOV (Flow Peening) Process
(Springer, 2025) Dogru, Mehmet Hanifi; Kalak, Murat; Sahin, Burak; Yeter, Eyup; Gov, Kursad
Inconel 718 was experimentally investigated in this paper due to the excellent mechanical properties and broad application area in aerospace industry. The purpose of current study is to improve surface strength of Inconel 718 samples having undesired white layer and microcracks because of electrical discharge machining process. In this research, newly developed GOV (flow peening) process by benefiting the superior capabilities of shot peening and abrasive flow machining such as generating compressive residual stresses which increases the corrosion resistance, surface strength, fatigue life and surface enhancement is applied to strengthen surfaces. SEM images were evaluated to verify the results of GOV process performance parameters on microhardness, residual stress, surface roughness and white layer removal. Consequently, compressive residual stress of - 1173.3 MPa, surface hardness of 545.5 HV and surface roughness Ra value of 0.46 mu m were obtained for Inconel 718 by GOV process.
Surface Treatment of AISI 304 Stainless Steel by GOV (Flow Peening) Process
(Springer Heidelberg, 2024) Sahin, Burak; Gov, Ibrahim; Kalak, Murat; Koca, Mustafa Sait; Gov, Kursad
AISI 304 stainless steel has extensive applications in different industries such as medical, automobile and molding due to its excellent mechanical features of poor thermal conductivity, high strength at high temperatures, and high corrosion resistance. However, it is difficult-to-process by traditional machining. Therefore, non-traditional surface treatment and finishing processes such as shot peening and abrasive-based methods are more applicable for this material. Considering the advantages of strength improvement and surface quality for shot peening and abrasive flow machining respectively, better advantages of these two processes are combined into a newly developed and patented process called as GOV (flow peening) process. In this paper, the effects of GOV process parameters (number of cycles, steel ball size, media ratio) on the surface quality of the AISI 304 in terms of surface roughness, white layer and material removal already pre-processed by electric discharge machining (EDM) were investigated. Surface finishing with GOV process decreases surface roughness R-a value from 2.34 & mu;m to 0.40 & mu;m by removing micro-level chips from specimen surface up to 11.5 mg. This material removal amount is supported by SEM images. It is obvious to understand that white layer formed owing to nature of EDM process is entirely removed from surface.