09 فروردین 1403
محمدعلي مهتدي بناب

محمدعلی مهتدی بناب

مرتبه علمی: دانشیار
نشانی: شهرستان بناب، بزرگراه ولایت، دانشگاه بناب، دانشکده مهندسی مکانیک
تحصیلات: دکترای تخصصی / مهندسی مکانیک
تلفن: 04137745000
دانشکده: دانشکده فنی و مهندسی
گروه: گروه مهندسی مکانیک

مشخصات پژوهش

عنوان
Finite element modeling of HIC propagation in pipeline steel with regard to experimental observations
نوع پژوهش مقاله چاپ شده
کلیدواژه‌ها
Hydrogen induced cracking, Crack propagation, Stepwise cracking Finite element modeling, Abaqus
پژوهشگران محمدعلی مهتدی بناب (نفر اول)، حجت موسوی (نفر دوم)، رضا پورعزیزی (نفر سوم)، Jerzy A. Szpunar (نفر چهارم)

چکیده

In this research, hydrogen induced cracking (HIC) phenomenon in pipeline steel has been investigated by finite element modeling (FEM) with the help of experimental observations. Abaqus software has been utilized to model the crack. To this, first an API 5L X70 pipeline steel was electrochemically charged by hydrogen for 8 h to create different types of HIC cracks. Then, SEM was used to observe different types of hydrogen cracks. Based on the observations, most of HIC cracks were observed at the center of cross section where center segregation of some elements occurred. The results showed that HIC cracks propagated in stepwise, sinusoidal, straight and disordered manner. Moreover, HIC crack nucleated from a point with high stress concentration factor which was between non-metallic inclusion or void and metal matrix. The initiated micro-cracks from two neighbor inclusions link together to form a long HIC crack. Based on the experimental observations and FEM modeling, it was concluded that the driving force for the HIC crack propagation is the presence of hydrogen at the crack tip after it is initiated. Crack tip usually acts as a very small void and the combination of hydrogen atoms makes a high pressure which propel the crack forward. Moreover, the HIC crack propagation path was predicted by fracture mechanics approach showing that the J-integral had its maximum amount when the HIC crack tended to propagate horizontally.