معادله رفتاری پایه فیزیکی برای پیش بینی تنش سیلان فولاد میکروآلیاژی در حین تغییرشکل داغ

نوع مقاله: مقاله پژوهشی

نویسنده

دانشیار، دانشکده مهندسی متالورژی و مواد، پردیس دانشکده‌های فنی دانشگاه تهران

چکیده

معادلات رفتاری بر پایه مکانیک نابجایی ها در دماهای نسبتا پایین قابل استفاده هستند. اما برای مدل کردن تنش سیلان در دماهای بالا، نیاز به در نظر گرفتن فرآیندهای نفوذی می باشد. به عبارتی، اثر نرم شوندگی بازیابی و تبلور مجدد دینامیکی باید درنظر گرفته شود. در تحقیق حاضر، یک معادله رفتاری اصلاح شده زریلی-آرم استرانگ برای پیش بینی تنش سیلان دمای بالای یک فولاد میکروآلیاژی ارایه شد که در آن اثرات سخت شوندگی و نرم شوندگی درنظر گرفته شده است. نشان داده شد که رابطه اصلی نمی تواند قسمت نرم شدن منحنی های سیلان که مربوط به تبلور مجدد دینامیکی است را مدل کند و مشخص شد که اصلاحاتی در ثوابت رابطه لازم است تا بازیابی دینامیکی به شکل مناسبی در نظر گرفته شود. از طرف دیگر، برای مدل کردن مناسب داده ها مشخص شد که باید مراحل سخت و نرم شدن را جداگانه در نظر گرفت و از کرنش پیک در رابطه تنش سیلان استفاده کرد. مدل توسعه یافته با وجود پایبندی به اصول مدل زریلی-آرم استرانگ به خوبی توانست تنش سیلان در دمای بالا را پیش بینی کند. در کل می توان این مدل را یک روش مناسب و ساده برای مدل کردن تنش سیلان فولادها دانست.

کلیدواژه‌ها


عنوان مقاله [English]

Physically-based constitutive equation for prediction of the flow stress of microalloyed steel during hot deformation

نویسنده [English]

  • Hamed Mirzadeh
Associate Professor, School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran
چکیده [English]

The constitutive equations based on the dislocation mechanics are applicable at relatively low temperatures. Nevertheless, considering the diffusion processes is necessary for modeling the hot flow stress. In other words, the softening effects of dynamic recovery and recrystallization should be taken into account. In the present work, a modified Zerilli–Armstrong constitutive equation for predicting the hot flow stress of a microalloyed steel was proposed, in which the effects of hardening and softening phenomena were contemplated. It was shown that the original equation is not able to model the softening part of flow curves related to dynamic recrystallization and it was clarified that the constants of the model should be modified for appropriate consideration of the effects of dynamic recovery. On the other hand, it was found that the hardening and softening stages should be separated and the peak strain can be utilized into the flow stress formula. While retaining the general form of the original Zerilli–Armstrong model, the developed constitutive relation was able to appropriately predict the hot flow stress. Conclusively, this constitutive model can be considered as a simple and viable one for modeling the flow stress of steels.

کلیدواژه‌ها [English]

  • Thermomechanical processing
  • Constitutive equations
  • Hot deformation
  • Dynamic recrystallization
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