بررسی تغییرات تنش سیلان فولاد 60SPb20 در آزمایش فشار دمای بالا

هادی, مرتضی; محمد شریفی, احسان; سامعی, محمد

doi:10.22076/me.2022.538371.1332

بررسی تغییرات تنش سیلان فولاد 60SPb20 در آزمایش فشار دمای بالا

نوع مقاله : مقاله پژوهشی

نویسندگان

¹ استادیار، گروه مهندسی مواد، دانشکده فنی مهندسی گلپایگان، دانشگاه صنعتی اصفهان، گلپایگان، ایران.

² استادیار، دانشکده مهندسی مواد، دانشگاه صنعتی مالک اشتر، اصفهان، ایران.

³ کارشناسی ارشد، دانشکده مهندسی مواد، دانشگاه صنعتی مالک اشتر، اصفهان، ایران.

10.22076/me.2022.538371.1332

چکیده

هدف از این پژوهش مطالعه بررسی رفتار کارداغ فولاد خوش‌تراش 60SPb20 در شرایط آزمایش فشاری دمای بالا و یافتن روابط کمی تنش سیلان با پارامترهایی مثل نرخ کرنش و دما بر پایه مدل آرنیوسی است. بدین منظور آزمایش‌های فشار روی نمونه‌های استاندارد از آلیاژ، در بازه دمایی 800 تا ^oC 1050 و در نرخ کرنش ۰۰۱/۰ تا s^-1 ۱ انجام شد. در آزمایشات فشار ضمن استفاده از روانکار دمای بالا، اثر اصطکاک بر تنش سیلان به کمک مدل اصلاحی حذف و منحنی‌های سیلان بدست آمده برای محاسبات مورد استفاده قرار گرفت. نتایج بدست آمده از منحنی‌های حاصل از آزمایش فشار داغ و بررسی‌های ریزساختاری نشان داد مکانیزم تبلور مجدد دینامیک باعث رخ دادن پدیده نرم شدن در دمای های بالا برای این فولاد است. در ضمن معادلات بنیادین فشار داغ با استفاده از پارامتر زنر- هولمن برای این فولاد تعیین شد. نتایج تغییرات تنش سیلان بر حسب دما در نرخ کرنشهای مختلف نشان داد انرژی فعال‌سازی تغییر شکل داغ برای فولاد خوش‌تراش 60SPb20، حدود kJ/mol 434 است. تفاوت بین این مقدار بدست آمده با فولادهای دیگری همچون فولاهای کم کربن و کربن متوسط و فولادهای ابزار و غیره تحلیل شد. نهایتا با محاسبه ثوابت لازم برای آلیاژ مذکور، رابطه تنش سیلان با پارامتر زنر- هولمن که برای پیش‌بینی رفتار تغییر شکل داغ در نرخ کرنش‌های بالاتر مورد استفاده است، تعیین شد.

کلیدواژه‌ها

20.1001.1.15631745.1400.24.3.2.8

عنوان مقاله [English]

Investigation of 60SPb20 steel flow stress changes in high-temperature compression tests

نویسندگان [English]

Morteza Hadi ¹
Ehsan Mohammad Sharifi ²
Mohammad Samei ³

¹ Assistant professor, Materials Engineering Group, Golpayegan College of Engineering, Isfahan University of Technology, Golpayegan, Iran.

² Assistant professor, Department of Materials Engineering, Malek-Ashtar University of Technology, Isfahan, Iran.

³ M.Sc. student, Department of Materials Engineering, Malek-Ashtar University of Technology, Isfahan, Iran.

چکیده [English]

The aim of this study was to investigate the behavior of 60SPb20 free-cutting steel at high-temperature compression tests and to find the relationships of flow stress with strain rate and temperature based on the Arrhenius model. For this purpose, compression tests were performed on standard samples of the alloy in the temperature range of 800 to 1050 °C and at a strain rate of 0.001 to 1 s^-1. In addition to the use of high-temperature lubricant, the effect of friction on flow stress was eliminated by a modification model and obtained flow curves were applied for further calculations. The compression curves and microstructural studies showed that the dynamic recrystallization mechanism was responsible for softening of the alloys at high temperatures. Moreover, the constitutive equations of hot deformation were determined using the Zener-Hollomon parameter for this steel. The results of changing the flow stress versus temperature at different strain rates showed that the activation energy of hot deformation of 60SPb20 free-cutting steel was about 434 kJ/mol. The difference between this value and values of other steels such as low and medium carbon steels, tool steels, etc. was discussed. Finally, after calculating the required constants for the alloy, the relation of flow stress versus the Zener-Hollomon parameter was determined which can be used to predict hot deformation behavior at higher strain rates.

کلیدواژه‌ها [English]

60SPb20 Free-cutting steel
Hot deformation behavior
Zener-Hollomon parameter
Dynamic recrystallization

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