مهندسی مکانیک مدرس

مهندسی مکانیک مدرس

اثر مسیر کرنش و پیری طبیعی بر ریزساختار و سختی آلیاژ آلومینیم AA7075

نوع مقاله : پژوهشی اصیل

نویسندگان
امیر کاظمی نوائی
روح‌اله جماعتی
حامد جمشیدی اول
دانشگاه صنعتی نوشیروانی بابل
10.52547/mme.22.11.669
چکیده
در تحقیق حاضر اثر مسیر کرنش توسط دو فرایند نورد نامتقارن مستقیم و نورد نامتقارن متقاطع و نیز پیری طبیعی روی ریزساختار و سختی آلیاژ آلومینیم AA7075 مورد بررسی قرار گرفت. ریزساختار توسط میکروسکوپ نوری و سختی توسط دستگاه سختی سنجی ماکرو ویکرز بررسی شد. نتایج نشان داد که نمونه‌ی عملیات محلولی شده (نمونه اولیه) دارای دانه‌های کشیده شده ناشی از نورد و میانگین عرض دانه‌ها در این نمونه برابر با 4/13 میکرومتر بوده است. با اعمال نورد نامتقارن مستقیم تا 60%، دانه‌ها کشیده‌تر شدند و میانگین عرض دانه‌ها به 6/2 میکرومتر رسید. با اعمال نورد نامتقارن متقاطع تا 40%، میانگین عرض دانه‌ها به 7/3 میکرومتر رسید. توزیع ذرات با اعمال نورد تغییر محسوسی نداشت. باندهای برشی نیز بعد از 40% و 60% نورد مستقیم، و نیز پس از 40% نورد متقاطع در ماده تشکیل شدند. در زمان پیری صفر، سختی نمونه‌ی 60% نورد مستقیم از نمونه‌ی 40% نورد متقاطع بیشتر بود. با افزایش زمان پیرسازی، سختی تمامی نمونه‌ها در اثر پیری طبیعی افزایش یافت. هر چه درصد کاهش ضخامت بیشتر شد (افزایش کرنش)، درصد افزایش سختی ناشی از پیری طبیعی کاهش پیدا کرد. افزایش سختی ناشی از پیری طبیعی در فرایند نورد متقاطع محسوس‌تر از فرایند نورد مستقیم بود. بعد از گذشت 7 روز پیری طبیعی، سختی ماده به حد اشباع خود رسید.
کلیدواژه‌ها
آلیاژ آلومینیم AA7075
نورد نامتقارن
مسیر کرنش
پیری طبیعی
ریزساختار
سختی

موضوعات

عنوان مقاله English

Effect of strain path and natural aging on the microstructure and hardness of AA7075 aluminum alloy

نویسندگان English

Amir Kazemi-Navaee
Roohollah Jamaati
Hamed Jamshidi Aval
Babol Noshirvani University of Technology
چکیده English

In the current research, the effect of strain path by two processes of conventional asymmetric rolling and asymmetric cross rolling, as well as natural aging on the microstructure and hardness of AA7075 aluminum alloy was investigated. The microstructure was examined by light microscopy and the hardness by macro-Vickers hardness tester. The results showed that the rolled sample (initial sample) had elongated grains due to rolling and the average width of the grains in this sample was 13.4 μm. By applying conventional asymmetric rolling up to 60%, the grains became more elongated and the average grain width reached 2.6 μm. By performing asymmetric cross rolling up to 40%, the average grain width reached 3.7 μm. The distribution of particles did not change significantly with rolling deformation. Shear bands were also formed in the sample after 40% and 60% conventional asymmetric rolling, as well as after 40% asymmetric cross rolling. At zero aging time, the hardness of the 60% conventionally rolled sample was higher than the 40% cross rolled sample. With increasing the aging time, the hardness of all samples increased due to natural aging. As the thickness reduction percentage increased (increasing the strain), the hardness increase percentage due to natural aging decreased. The increase in hardness due to natural aging was more noticeable in the cross-rolling process than in the conventional rolling process. After 7 days of natural aging, the hardness of the material reached its saturation limit.

کلیدواژه‌ها English

AA7075 aluminum alloy
Asymmetric rolling
Strain path
Natural aging
Microstructure
Hardness
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مهندسی مکانیک مدرس
دوره 22، شماره 11
آبان 1401
صفحه 669-675