Browsing by Author "Baltacioglu, Mehmet Furkan"

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The Effect of Strain Rate on the Hydrogen Embrittlement Susceptibility of Aluminum 7075
(ASME, 2023) Baltacioglu, Mehmet Furkan; Bal, Burak; Cetin, Baris; 0000-0002-7389-9155; AGÜ, Mühendislik Fakültesi, Makine Mühendisliği Bölümü; Baltacioglu, Mehmet Furkan; Bal, Burak
The effects of changing the strain rate regime from quasi-static to medium on hydrogen susceptibility of aluminum (Al) 7075 were investigated using tensile tests. Strain rates were selected as 1 s(-1) and 10(-3) s(-1) and tensile tests were conducted on both hydrogen uncharged and hydrogen charged specimens at room temperature. Electrochemical hydrogen charging method was utilized and the diffusion length of hydrogen inside Al 7075 was modeled. Material characterizations were carried out by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX) and microstructural observations of hydrogen uncharged and hydrogen charged specimens were performed by scanning electron microscope (SEM). As opposed to earlier studies, hydrogen embrittlement (HE) was more pronounced at high strain rate cases. Moreover, hydrogen enhanced localized plasticity (HELP) was the more dominant hydrogen embrittlement mechanism at slower strain rate but coexistence of hydrogen enhanced localized plasticity and hydrogen enhanced decohesion was observed at a medium strain rate. Overall, the current findings shed light on the complicated hydrogen embrittlement behavior of Al 7075 and constitute an efficient guideline for the usage of Al 7075 that can be subject to different strain rate loadings in service.
Hydrogen susceptibility of Al 5083 under ultra-high strain rate ballistic loading
(Walter de Gruyter GmbH, 2024) Baltacioglu, Mehmet Furkan; Mozafari, Farzin; Aydin, Murat; Cetin, Baris; Oktan, Aynur Didem; Teoman, Atanur; Li, Yang; Bal, Burak; 0000-0001-8218-4410; 0000-0002-7389-9155; 0000-0001-6476-0429; AGÜ, Mühendislik Fakültesi, Makine Mühendisliği Bölümü; Baltacioglu, Mehmet Furkan; Mozafari, Farzin; Bal, Burak
The effect of hydrogen on the ballistic performance of aluminum (Al) 5083H131 was examined both experimentally and numerically in this study. Ballistics tests were conducted at a 30° obliquity in accordance with the ballistic test standard MIL-DTL-46027 K. The strike velocities of projectiles were ranged from 240 m s−1 to 500 m s−1 level in the room temperature. Electrochemical hydrogen charging method was utilized to introduce hydrogen into material. Chemical composition of material was analyzed using energy dispersive X-ray (EDX) analysis. Instant camera pictures were captured using high-speed camera to compare H-uncharged and H-charged specimen ballistics tests. The volume loss in partially penetrated specimens were assessed using the 3D laser scanning method. Microstructural examinations were conducted utilizing scanning electron microscopy (SEM). It was observed that with the increased deformation rate, the dominance of the HEDE mechanism over HELP became evident. Furthermore, the experimental findings were corroborated through numerical methods employing finite element analysis (FEM) along with the Johnson–Cook plasticity model and failure criteria. Inverse optimization technique was employed to implement and fine-tune the Johnson–Cook parameters for H-charged conditions. Upon comparing the experimental and numerical outcomes, a high degree of consistency was observed, indicating the effective performance of the model.
A phenomenological hydrogen induced edge dislocation mobility law for bcc Fe obtained by molecular dynamics
(ELSEVIER, 2024) Baltacioglu, Mehmet Furkan; Kapci, Mehmet Fazil; Schön, J. Christian; Marian, Jaime; Bal, Burak; 0000-0002-7389-9155; 0000-0001-6476-0429; AGÜ, Mühendislik Fakültesi, Makine Mühendisliği Bölümü; Baltacioglu, Mehmet Furkan; Kapci, Mehmet Fazil; Bal, Burak
Investigating the interaction between hydrogen and dislocations is essential for understanding the origin of hydrogen-related fractures, specifically hydrogen embrittlement (HE). This study investigates the effect of hydrogen on the mobility of ½<111>{110} and ½<111>{112} edge dislocations in body-centered cubic (BCC) iron (Fe). Specifically, molecular dynamics (MD) simulations are conducted at various stress levels and temperatures for hydrogen-free and hydrogen-containing lattices. The results show that hydrogen significantly reduces dislocation velocities due to the pinning effect. Based on the results of MD simulations, phenomenological mobility laws for both types of dislocations as a function of stress, temperature and hydrogen concentration are proposed. Current findings provide a comprehensive model for predicting dislocation behavior in hydrogen-containing BCC lattices, thus enhancing the understanding of HE. Additionally, the mobility laws can be utilized in dislocation dynamics simulations to investigate hydrogen-dislocation interactions on a larger scale, aiding in the design of HE-resilient materials for industrial applications.