فراوری فولاد ساده کربنی فوق ریز دانه از طریق دگرگونی دینامیکی تحت کرنش آستنیت به فریت در حین تغییر شکل با روش تلفیقی اکستروژن- پرس

نویسندگان

1 1- دانشکده فنی، دانشگاه مراغه

2 2- دانشگاه فنی و حرفه‌ای، آموزشکده شماره 2 تبریز

3 3- باشگاه پژوهشگران جوان و نخبگان، دانشگاه آزاداسلامی، واحد ایلخچی

چکیده

در پژوهش حاضر، یک نوع فولاد ساده کربنی با ساختار فوق ریز دانه با اعمال یک فرایند ترمومکانیکی موثر در گستره دمایی آستنیت شبه پایدار (Ae3-Ar3) و با استفاده از روش تلفیقی اکستروژن - پرس در کانال‌های زاویه ­دار با مقاطع همسان فراوری شد. در ابتدا با استفاده از تحلیل المان محدود سه بعدی دما - جابه‌جایی، تاثیر دمای پیشگرم در توزیع کرنش و دما در نمونه‌های تغییر شکل داده شده مورد بررسی قرار گرفت. با استفاده از نتایج به‌دست آمده، دمای 930 درجه سانتی‌گراد به‌عنوان مناسب‌ترین دمای پیشگرم برای دستیابی به ساختار فوق ریز دانه از طریق وقوع دگرگونی دینامیکی آستنیت به فریت انتخاب شد. با اعمال تغییر شکل بر روی فولاد مورد نظر در این دمای پیشگرم و بررسی ریزساختار نهایی، نتایج حاصل از تحلیل المان محدود مورد تایید قرار گرفت. نتایج نشان داد که در اثر این فرایند ترمو‌مکانیکی اندازه دانه‌های فریت از 32 میکرومتر در ساختار اولیه به 1 تا 3 میکرومتر پس از اعمال فرایند کاهش پیدا می‌کند.

کلیدواژه‌ها

عنوان مقاله [English]

Fabrication of Ultra-Fine Grained Plain Low Carbon Steel through Dynamic Strain Induced Transformation during Integrated Extrusion Equal Channel Angular Pressing

نویسندگان [English]

  • H. Shokrvash 1
  • A. Vajd 2
  • M. Shaban Ghazani 3
1 1- Faculty of Engineering, University of Maragheh, Maragheh, Iran.
2 2- Technical College of Tabriz No.2, Technical and Vocational University, Tabriz, Iran.
3 3- Young Researchers and Elite Club, Islamic Azad University, Ilkhchi branch, Iran
چکیده [English]

In the present research, an effective thermo-mechanical processing route in the temperature range of metastable austenite region (Ae3<T< Ar3) was employed to achieve ultra-fine grain size in a plain low carbon steel during integrated extrusion equal channel angular pressing. At first, the effect of preheating temperature on the strain and temperature distributions inside the deformed samples were investigated using 3D finite element simulation. According to the result of FEM simulation, the preheating temperature of 930 ˚C was selected as an appropriate temperature for fabrication of ultra-fine ferrite structure. Severe plastic deformation was then imposed on samples with the predicted preheating temperature and the results showed a great consistency with FEM simulation predictions. Optical micrographs taken from the center point of the  samples showed that the ferrite grains could be refined from 32 &mu;m to 1-3 &mu;m by different mechanisms.

کلیدواژه‌ها [English]

  • Finite element simulation
  • Severe plastic deformation
  • Ultra-fine grained steel

مراجع

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مواد پیشرفته در مهندسی
دوره 34، شماره 4
اسفند 1394
صفحه 73-85

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