بررسی رسوب‌گذاری دینامیکی حین تغییر شکل پلاستیک شدید آلیاژ ریختگی AZ91 و تأثیر آن بر ریزساختار و خواص مکانیکی

نوع مقاله : علمی و پژوهشی

نویسندگان

• سمیه خانی
• محمد تقی صالحی
• حمید رضا صمیم بنی هاشم
• محمدرضا ابوطالبی

علم و صنعت ایران

10.22067/ma.v30i2.57423

چکیده

فرآیند تغییر شکل پلاستیک شدید آلیاژ AZ91 به روش فشردن در کانال زاویه‌دار با مقاطع یکسان طی دو مرحله، شامل پاس اول تغییر شکل در ۳۵۰ درجه سانتیگراد و اعمال پاس‌های بعدی در دمای 29۰ درجه سانتیگراد صورت گرفت. این فرآیند به طور مؤثری سبب ریزدانه شدن ساختار آلیاژ شد. نتایج بدست آمده نشان داد، در حین تغییر شکل، رسوب‌گذاری دینامیکی به طور همزمان با تبلورمجدد دینامیکی اتفاق می‌افتد و حضور رسوبات در ساختار می‌تواند سبب تقویت تبلورمجدد دینامیکی شود. با توجه به بررسی‌های ریزساختاری، رسوب‌گذاری دینامیکی هنگام عبور از ناحیه برشی تحت تأثیر اعمال کرنش برشی و حضور دانسیته بالای نابجایی‌ها اتفاق می‌افتد. نتایج آزمون کشش در دمای محیط، بهبود همزمان استحکام تسلیم و داکتیلیته آلیاژ پس از فشردن در کانال زاویه‌دار با مقاطع یکسان را نشان داد.

کلیدواژه‌ها

• تغییر شکل شدید پلاستیکی
• پرس در کانال زاویه‌دار با مقاطع یکسان
• آلیاژ AZ91
• تبلور مجدد دینامیکی
• رسوب‌گذاری دینامیکی

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عنوان مقاله [English]

Study of Dynamic Precipitation during Severe Plastic Deformation of Cast AZ91 Alloy and Its Influence on Microstructure and Mechanical Properties

نویسندگان [English]

• Somayeh Khani
• Mohammad Taghi Salehi
• Hamid Reza Samim Banihashem
• m abuotalebi

Iran University of Science and Technology

چکیده [English]

In this study severe plastic deformation was applied to a typical as-cast AZ91 alloy through equal channel angular pressing. The equal channel angular pressing of AZ91 alloy was carried out as a two-step process in which the first equal channel angular pressing pass was conducted at 350° Cand the next passes were followed at 290°. The equal channel angular pressing processing could strongly refine the grains. The results showed that dynamic precipitation and dynamic recrystallization occurred simultaneously leading to an enhancement of the recrystallization process. Microstructural investigations indicated that the formation of precipitates starts at shear zone as a result of the large shear strains and high density of dislocations. The analysis of tensile test results showed that the equal channel angular pressing can significantly improve both yield strength and ductility of AZ91 alloy.

کلیدواژه‌ها [English]

• Severe Plastic Deformation
• Equal Channel Angular Pressing
• AZ91 Alloy
• Dynamic Recrystallization
• Dynamic Precipitation

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