دانلود مقاله ساختار میکرو/نانو منجر به استحکام و انعطاف پذیری در فولاد ضدزنگ 304
چکیده
مقدمه
مطالب و روش تجربی
نتایج
بحث
نتیجه گیری
منابع
Abstract
Introduction
Materials and experimental procedure
Results
Discussion
Conclusions
References
چکیده
ساختار میکرو/نانو یکی از انواع مهم ساخت و سازهای چندلایه است که می تواند فلزات و آلیاژهای نانو کریستالی با خواص مکانیکی جامع عالی بسازد. با استفاده از واکنش Aluminothermic (AR) و نورد متعاقب آن با تغییر شکل 50 درصد در دمای اتاق (RT) و به دنبال آنیل شدن در دمای 973 K به مدت 1 ساعت، یک ساختار ترکیبی ناهمگن از فولاد ضد زنگ 304 با ساختار میکرو/نانو (SS) ایجاد می‌شود. به دست آمده. چنین نمونه فولاد ضد زنگ دارای استحکام کششی تا 1023 مگاپاسکال و ازدیاد طول تا شکست حدود 27.3٪ است. در این فرآیند، استحکام بسیار بالا از تقویت مارتنزیت، پالایش دانه آستنیت و افزایش چگالی نابجایی ناشی می‌شود، در حالی که شکل‌پذیری از تبلور مجدد آستنیت تغییر شکل یافته و بازیابی مارتنزیت ناشی از کرنش افزایش می‌یابد. ترکیب مقاومت و شکل‌پذیری برتر در 304 SS با ساختار میکرو/نانو به دست می‌آید که رویکرد جدیدی را برای بهینه‌سازی خواص مکانیکی در مواد مهندسی نشان می‌دهد.
توجه! این متن ترجمه ماشینی بوده و توسط مترجمین ای ترجمه، ترجمه نشده است.
Abstract
Micro/nano-structure is one of the important types of multilayer construction, which can make nanocrystalline metals and alloys with excellent comprehensive mechanical properties. By means of Aluminothermic Reaction (AR) and subsequent rolling with deformation of 50% at room temperature (RT) and followed by annealed at 973 K for 1 h, a heterogeneous composite structure of micro/nano-structured 304 stainless steel (SS) is obtained. Such a stainless steel specimen exhibits a tensile strength as high as 1023 MPa and an elongation-to-failure of about 27.3%. In the process, the much elevated strength originates from martensite strengthening, austenite grain refinement and dislocation density increasing, while ductility promotes from the recrystallization of deformed austenite and recovery of strain induced martensite. Superior strength–ductility combination achieves in micro/nano-structured 304 SS, which demonstrates a novel approach for optimizing the mechanical properties in engineering materials.
Introduction
304 stainless steel (SS) (0Cr18Ni9) was a kind of universal stainless steel. It was widely used in aerospace, chemical energy, automobile industry, shipbuilding, food, medical industry and other fields [[1], [2], [3]]. The modern industry had put forward a higher demand for 304 SS, and the research of high strength and high plastic steel had become a great focus in recent years [[4], [5], [6], [7]].
It had been found that biomaterials with excellent comprehensive mechanical properties always had more complex structural features [8,9], such as uneven geometry [10], spatial distribution [11], multi-scale, non-uniform tissues distribution [12] and multi-level coupling structure [13], etc. They could effectively overcome performance defects of single homogeneous ultrafine/nanocrystalline structure materials and significantly improved plastic deformation ability [14,15]. The unique micro/nano-structure of biomaterials had become a source of innovation in the design and preparation of new composite materials [16,17]. Micro/nano-structure was one of the important types of multilayer construction [[18], [19], [20]]. Herein, we reported a micro/nano-structured 304 SS which was achieved the imhomogeneous structure via Aluminothermic Reaction (AR) experiments [[21], [22], [23]], and subsequent different rolling and annealing schedule to control different microstructures. This micro/nano-structured 304 SS achieved the best match between strength and plasticity.
Conclusions
Hierarchical structured 304 SS with heterogeneous grains from nanoscale to microscale was prepared via AR. The main conclusions are listed as follows:
(1) With the progress of rolling deformation for 50% at RT, austenite grain size decreased, the content of strain induced martensite and dislocation density increased obviously. Here, heterogeneous composite structure were obtained, which composed of high density dislocation, deformation twin, strain induced martensite and microcrystalline grains/ultra-fine grains/nanocrystalline grains.
(2) After annealing treatment, deformed austenite was recrystallized, defects such as dislocations and twins in deformed austenite were eliminated gradually, content of nanocrystalline austenite was increased, and grain size growth of recrystallized ultrafine and nanocrystalline austenite was not obvious owing to low annealing temperatures.
(3) The excellent combination of strength and plasticity for micro/nano-structured 304 SS was attributed to the obstruction of dislocation by nanocrystalline austenite and residual martensite, as well as high work hardening ability of micro/nano-structured heterogeneous composite structure.