خواص مکانیکی و مطالعه برگشت فنری در فرایند شکل‌دهی خزشی آلیاژ آلومینیم 7075

نویسندگان

گروه مهندسی مواد، دانشکده فنی و مهندسی، دانشگاه تربیت مدرس

چکیده

فرایند شکل­‌دهی خزشی از جمله فرایند­های نوینی است که به‌دلیل بهبود خواص مکانیکی و کاهش هزینه­ های تولید در صنایع هوایی توسعه یافته ­است. شکل­‌دهی خزشی بر اساس پدیده­ خزش و آزادسازی تنش در حین عملیات پیرسازی آلیاژهای عملیات حرارتی‌پذیر آلومینیوم رخ می­دهد. در این پژوهش، شکل­دهی خزشی آلیاژ آلومینیوم 7075 در دماهای 120، 150 و 180 درجه سانتی­گراد و زمان‌های 6، 24 و 48 ساعت انجام­ شد و از آزمون ­های کشش و سختی برای مشخصه ­یابی نمونه­ ها استفاده شد. با اندازه­‌گیری میزان برگشت‌­فنری مشخص شد که این پاسخ تابع دما و زمان بوده و با افزایش دما و زمان شکل­دهی خزشی، از 1/54 درصد به 51/39 درصد کاهش می­یابد. خواص مکانیکی نمونه ­ها نشان داد که با افزایش زمان شکل­دهی، استحکام و سختی افزایش می­یابد که دلیل آن، می ­تواند تحولات ریزساختاری ناشی از فرایند رسوب­گذاری در حین شکل‌­دهی خزشی باشد. با توجه به نتایج، دو نمونه به‌عنوان نمونه­ های بهینه از نظر برگشت ­فنری و خواص مکانیکی انتخاب شدند و رفتار کارسختی و مورفولوژی سطح شکست آنها بررسی شد.

کلیدواژه‌ها

عنوان مقاله [English]

Mechanical Properties and Spring -Back Investigation in Creep Age Forming Process of 7075 Al Alloy

نویسندگان [English]

  • H. R. Shahverdi
  • R. Alipour Mogadam
Materials Engineering Department, Engineering Faculty ,Tarbiat Modares University, Tehran, Iran.
چکیده [English]

Creep age forming (CAF) process is a novel metal forming method with major benefits including improved mechanical properties and cost reduction for aviation industry applications. CAF happens due to creep phenomenon and stress-release during the artificial aging of heat-treatable  aluminum alloys. In this work, the creep age forming of 7075 Aluminum alloy at 120, 150 and 180 °C for 6, 24 and 48 h was done; tensile and hardness tests were used to characterize the samples. Results on spring-back revealed that it was influenced by time and temperature;  by increasing the time and temperature, it was reduced from 54.1 to 39.51. Mechanical property evaluation also showed that by increasing the time, the strength and hardness could be enhanced due to microstructural evolution and precipitation during the CAF process. According to the mechanical and CAF results, two samples were selected as the optimum ones and their work hardening behavior and fracture surfaces were investigated

کلیدواژه‌ها [English]

  • Creep-age Forming
  • 7075 Aluminum Alloy
  • Springback
  • mechanical properties

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مواد پیشرفته در مهندسی
دوره 38، شماره 2
شهریور 1398
صفحه 55-67

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