Person: ERTAN, RUKİYE
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ERTAN
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RUKİYE
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Publication A comparative study on conventional and hybrid quenching hot forming methods of 22mnb5 steel for mechanical properties and microstructure(Springer, 2022-08-01) Eşiyok, Ferdi; Ertan, Rukiye; Sevilgen, Gökhan; Bulut, Emre; Özturk, Ferruh; Alyay, İlhan; Abi, Tuğçe Turan; ERTAN, RUKİYE; SEVİLGEN, GÖKHAN; BULUT, EMRE; ÖZTÜRK, FERRUH; Mühendislik Fakültesi; Otomotiv Mühendisliği Bölümü; 0000-0002-7746-2014; 0000-0001-9159-5000; KIH-2391-2024; JIW-7185-2023; JCO-2416-2023; ABG-3444-2020In this paper, the conventional hot forming and hybrid quenching hot forming processes of Al-Si-coated 22MnB5 steel sheet were investigated and compared at 0.5 s-15 s holding times in the press tool related to the mechanical properties, microstructure, and dimensional accuracy. The conventional hot forming method is classified as a direct method and an indirect method. Both methods have limitations due to processing time and cooling of the press tool. To speed up the process, an alternative cooling method based on spray or jet cooling was used outside of the die tool. The hybrid quenching method involves hot forming and spray cooling process. This method, using spray parameters, provides more effective control in mechanical properties and microstructure compared to the conventional method by using spray parameters. Vickers hardness tests and tensile tests were carried out to compare mechanical properties. Changes in the microstructure of the materials were investigated using an optical microscope. The results show that spray cooling can be used as part of quenching in the hot forming process by reducing the holding time in the press tool by 97%. However, the microstructure, mechanical properties, and geometry deviations of the stamped parts are still below tolerances after the hybrid quenching hot forming process. The use of the hybrid quenching method with multi-point nozzles in the hot forming process resulted in sheet hardness up to 470 HV1 and 8% elongation with tensile strength of 1500 MPa.Publication Investigation of the welding capability of aluminum and titanium alloy sheets with if steel sheets by resistance spot welding method(Gazi Üniversitesi, 2020-12-01) Mutlusu, Özer; Ertan, Rukiye; ERTAN, RUKİYE; Mühendislik Fakültesi; KIH-2391-2024In this study, spot weldability of 1 mm thick IF 180 deep drawn high strength steel with 1 mm thick commercial pure titanium (ASTM Grade 2) and 5754 aluminum alloy was investigated. The welding operations were performed with different welding currents (10 kA, 12.5 kA and 15 kA), welding times (10, 15 and 20 cycles) and electrode forces (5 kN, 10 kN and 15 kN) by electrical resistance spot welding. The welding nugget diameter, electrode immersion depth, hardness and tensile-shear test results of the welded samples were examined and the mechanical properties were compared. As a result of the tests, it was seen that the welding parameters had a greater effect on the mechanical properties of the IF 180-5754 Al alloy welding pair than the IF 180 - Ti-Gr2 alloy pair. It has been determined that the welding current and electrode force significantly affect the nugget diameter, electrode immersion depth and the maximum tensile force in both welding pairs.Publication Effect of temperature and rolling direction on the formability of cp2 and ti-6al-4v titanium materials(Walter De Gruyter Gmbh, 2023-09-13) Gökmen, Şaban; Ertan, Rukiye; ERTAN, RUKİYE; Özgül, Hande Güler; GÜLER ÖZGÜL, HANDE; Mühendislik Fakültesi; GWU-9651-2022; KIH-2391-2024Pure (CP2) and alloyed titanium (Ti-6Al-4V) have an important place in biomedical and aerospace applications due to their low density and high strength properties. In this study, the effect of the formability of CP2 and Ti-6Al-4V titanium alloy at different temperatures on mechanical properties and microstructure was investigated. The hot forming process was carried out by pressing 1 mm sheet titanium plates at different temperatures on the U profile mold. Specimens along the rolling direction and perpendicular to the rolling direction were taken from the bottom the formed U-plates. Afterward, tensile tests, microhardness measurements, and changes in microstructure were examined, respectively. As a result, at high temperatures and in different rolling directions, significant changes in microstructure and mechanical properties were observed. It was determined that the best forming temperature of CP2 and Ti-6Al-4V materials along the rolling direction was 500 degrees C, white it is 400 degrees for perpendicular to the rolling direction was 400 degrees C.Publication The investigation of the effects of spray parameters on the thermal and mechanical properties of 22MnB5 steel during hybrid quenching process(Begell House, 2021-01-01) Sevilgen, Gökhan; Ertan, Rukiye; Bulut, Emre; Öztürk, Ferruh; Eşiyok, Ferdi; Abi, Tuğçe Turan; Alyay, İlhan; SEVİLGEN, GÖKHAN; ERTAN, RUKİYE; BULUT, EMRE; ÖZTÜRK, FERRUH; Mühendislik Fakültesi; Otomotiv Mühendisliği Bölümü; 0000-0002-7746-2014; 0000-0001-9159-5000; ABG-3444-2020; KIH-2391-2024; AAG-8907-2021; JIW-7185-2023In this paper, the investigation of the effects of spray parameters on the thermal and mechanical properties of 22MnB5 steel during the hybrid quenching (HQ) process was performed. The HQ method presented in this study includes early removal of hot-stamped parts from the die and transfer to an external multinozzle spray cooling device. The proposed method was developed due to the need for improving disadvantages of the traditional hot stamping process such as complexity of controlling the cooling rate during die quenching by using cooling channels and of providing the reduced tool contact surface temperature after a certain cycle of the hot stamping process. This paper focuses on the temperature distribution and mechanical characteristics of high-strength 22MnB5 steel during the HQ process. Moreover, the methodology developed in this paper can be used to get tailored parts where the cooling rates are locally chosen to achieve structures with graded properties, i.e., to allow local modification of final mechanical properties in order to provide high energy absorption to enhance the crashworthiness of the whole component and thus to improve the vehicle safety performance. The three-dimensional numerical model of spray cooling was also developed by using the computational fluid dynamics (CFD) method to get the suitable process parameters such as spray height and initial blank temperature and to present the detailed heat transfer analysis of hot-stamped parts during the hybrid quenching process.Publication Effect of deformation temperature on mechanical properties, microstructure, and springback of Ti-6Al-4V sheets(Consejo Superior Investigaciones Cientificas-csic, 2021-10-01) Ertan, Rukiye; Çetin, Güner; ERTAN, RUKİYE; Mühendislik Fakültesi; Otomotiv Mühendisliği Bölümü; KIH-2391-2024Ti-6Al-4V titanium alloy is applied in various industrial applications such as aerospace, jet engine, and automotive industries due to its strength-to-weight ratio and excellent high-temperature properties. For these demanding applications, the formability of the material and the effect of forming parameters on the final mechanical properties are of great importance. In this study, the springback behavior of hot-formed 1 mm sheet Ti-6Al-4V alloy was investigated related to the deformation temperature ranging from 350 to 950 degrees C. After the hot forming, the springback angles of the U profile were examined and associated with the mechanical properties and the microstructural evolution. The microstructure changing mechanisms were mapped at each temperature of deformed sheets with the help of optical microscopy. As a result, it was observed that important microstructural changes have occurred, such as recrystallization, grain growth, and phase transformations, which themselves greatly influence the springback angle and the mechanical properties. The formability of the Ti-6Al-4V sheet material was found to be strongly dependent on the applied process temperatures and the activated microstructural deformation mechanisms. Hot forming at 850 degrees C leads to the lowest springback angle, but after the hot-forming, pronounced softening of the material occurs due to the recrystallization.Publication The flexural behavior of the epoxy and polyester based composite sandwich structures at subzero temperatures(Elsevier, 2020-08-01) Ertan, Rukiye; Kuş, Abdil; Durgun, İsmail; ERTAN, RUKİYE; KUŞ, ABDİL; Mühendislik Fakültesi,; Otomotiv Mühendisliği Bölümü; AAG-9412-2021; KIH-2391-2024The present work aims at characterizing the 3D woven spacer composites with carbon fiber reinforced polymer face-sheets under the 3-point flexural test at subzero temperature conditions. For this purpose, sandwich composite panels are manufactured using vacuum assisted resin infusion method for epoxy and polyester matrix materials with 2, 3, and 4 layered face-sheets. The 3-point flexural test was performed for warp and weft direction on liquid nitrogen temperature (-40 degrees C). Macroscopic fracture morphology was examined to understand the deformation and failure mechanism. The results show that the flexural properties were significantly affected by the number of face-sheets and then from matrix material and finally from the composite direction at subzero temperatures.