نوع مقاله : مقاله کامل پژوهشی

نویسندگان

1 گروه مهندسی مکانیک دانشکده فنی و مهندسی، دانشگاه مراغه

2 دانشجوی دکتری، دانشکده مهندسی مواد و متالورژی، دانشگاه علم و صنعت ایران

3 دانشکده مهندسی مواد و متالورژی، دانشگاه علم و صنعت ایران، تهران، ایران

چکیده

در این پژوهش، نمونه­های آلومینیوم خالص 1050 بطور موفقیت­آمیزی تحت فرایند اصطکاکی اغتشاشی تا شش پاس قرار گرفته و سپس، خواص مکانیکی، الکتریکی و ریزساختاری نمونه­های فراوری شده بدست آمده و با نمونه اولیه مقایسه گردیده است. نتایج حاکی از افزایش استحکام تسلیم، استحکام نهایی و سختی نمونه در اثر اعمال این فرایند می­باشد. مشخص گردید، میزان بهبود خواص مکانیکی در پاس­های بعدی چشمگیر نیست و نیز می­توان گفت که با دور شدن از مرکز، مقدار میکروسختی بتدریج و با شیب ملایم کاهش می­یابد. اگرچه شکل­پذیری نمونه بعد از اعمال اولین پاس کاهش می­یابد افزایش تعداد پاس­ها، مقدار شکل­پذیری نمونه را در مقایسه با حالت تک پاسه بهبود می­دهد. نتایج ریزساختاری نشان داد که با انجام یک پاس از فرایند مذکور، میکروساختار بشدت تغییر پیدا کرده و میزان مرزهای بزرگ زاویه بشدت افت پیدا می­کند که می­تواند دلیل اصلی کاهش هدایت الکتریکی نمونه یک پاسه در مقایسه با نمونه اولیه باشد. افزایش تعداد پاس­ها موجب افزایش چگالی نابجایی­ها، تبدیل مرز­های کوچک به بزرگ زاویه و تقاطع بالای میکروباند­های برشی بعد از اعمال هر پاس می­گردد که موجب بهبود شکل­پذیری نمونه و افزایش هدایت الکتریکی آن در مقایسه با نمونه تک پاسه می­شود. لذا، این فرایند قابلیت لازم برای بهبود همزمان خواص مکانیکی و حفظ خواص الکتریکی را داراست.

کلیدواژه‌ها

عنوان مقاله [English]

Enhanced mechanical properties of pure aluminum by friction stir processing

نویسندگان [English]

  • M Ebrahimi 1
  • SHokoh Attarilar 2
  • mohammad Taghi Salehi 3

1 Department of Mechanical Engineering, Faculty of Engineering, University of Maragheh

2 School of Metallurgy and Materials Engineering, Iran University of Science and Technology

چکیده [English]

In this work, commercial pure aluminum was subjected to friction stir processing (FSP) up to six passes, then, mechanical properties, electrical conductivity, and microstructure analysis of the processed samples were compared with the initial condition. Better yield strength, ultimate tensile strength, and hardness are achieved after imposing the process. Also, strengthening rate is reduced at the subsequent passes. It was found that hardness magnitude is decreased mildly by getting away from the center. Although material formability is reduced after the first pass, it is grown a little by adding the pass number. The microstructure analysis indicated that application of one pass FSP changes considerably grain size of the annealed aluminum and leads to extreme decrease of the high angle grain boundaries density which plays the main role in the reduction of electrical conductivity. Addition of FSP pass number leads to increment of dislocations density, transformation of low-angle to high-angle grain boundaries, and the further intersection of shear microbands, causing improvement of sample formability and electrical conductivity compared to the first pass. Therefore, this process has the capability for fabrication of pure aluminum with improved mechanical properties and acceptable electrical conductivity.

کلیدواژه‌ها [English]

  • Friction stir processing
  • Commercial pure aluminum
  • Mechanical properties
  • Electrical conductivity
  • Microstructure analysis
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