초록

■ 강소성 가공 공정을 이용하여 벌크 나노철강재료를 개발하였음
■ 벌크 나노철강재료의 기계적 / 미세구조적 특성을 평가하였음
■ 2.5 GPa 이상의 강도 및 5%의 연성을 가지는 벌크 나노철강재료를 획득하였음
■ 전산모사를 통해 벌크 나노철강재료 가공 시 미세구조의 변화를 예측하였음


(출처 : 보고서 요약서 3P)

Abstract ▼

Recently, the demand for high-strength metallic materials is increased in automotive, aerospace, architecture, and military industries. Especially, extreme service conditions require higher strength and more stable materials to enhance the performance, lifetime, and reliability of the products. To a

Recently, the demand for high-strength metallic materials is increased in automotive, aerospace, architecture, and military industries. Especially, extreme service conditions require higher strength and more stable materials to enhance the performance, lifetime, and reliability of the products. To achieve these requirements in steel making industry, thermo-mechanical treatment (TMT) processing has been applied to austenitic steels. This process is efficient to enhance the strength of steels, but reduces ductility and corrosion resistance due to the martensitic phase transformation. Thus, current state-of-the-art technology has a limitation in achieving high strength or high stability.

In this research, the multi-strengthening mechanisms based bulk nano-ferrous alloy is developed via severe plastic deformation processes, i.e., high-pressure torsion and equal-channel angular pressing. The mechanical and microstructural properties of the developed nano-ferrous alloys are unveiled by tensile testing, transmission electron microscopy, and 3-dimensional atom probe tomography.

From these studies, the bulk nano-ferrous alloy which contains 45 nm grain size is fabricated using the high-pressure torsion process. In particular, in the high processing temperature (300 ℃), 3-dimensional grain boundary segregation structure was constructed due to the carbon atom migration. The multi-strengthening mechanisms, i.e., nano-twin strengthening and segregation strengthening in the nano-ferrous alloy are unveiled by microstructural analyses. Finally, the strength of the nano-ferrous alloy is higher than 2.5 GPa which is the largest strength in the bulk metallic materials.

This result represents a new strengthening strategy which combines more than four strengthening mechanisms simultaneously in the nanocrystalline materials. Such a strategy is suitable to apply for the extreme materials, and sufficient to preserve as an intellectual property right. Thus, POSTECH and USATU applied patents each other and tried to apply it in the industrial field.


(출처 : SUMMARY 5P)

목차 Contents

• 표지 ... 1
• 제 출 문 ... 2
• 보고서 요약서 ... 3
• 요 약 문 ... 4
• SUMMARY ... 5
• CONTENTS ... 6
• 목차 ... 7
• 제 1장 연구개발과제의 개요 ... 8
• 제 1절 연구개발의 목적 및 필요성 ... 8
• 제 2절 연구개발의 내용 및 범위 ... 10
• 제 2장 국내외 기술개발 현황 ... 12
• 제 1절 국내외 기술개발 현황 ... 12
• 제 2절 기술개발 현황에서의 현 위치 ... 15
• 제 3장 연구개발수행 내용 및 결과 ... 16
• 제 1절 강소성 가공공정에 의한 나노철강소재 개발 ... 16
• 제 2절 나노철강소재의 기계적 특성 평가 ... 20
• 제 3절 나노철강소재의 미세구조적 특성 평가 ... 23
• 제 4장 목표달성도 및 관련분야에의 기여도 ... 29
• 제 1절 연구개발목표의 달성도 ... 29
• 제 2절 관련 분야의 기술발전에의 기여도 ... 31
• 제 5장 연구개발결과의 활용계획 ... 34
• 제 6장 참고문헌 ... 35
• 끝페이지 ... 36