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Study on role of dynamic recrystallization in fine-structure superplasticity.

Research Project

Project/Area Number 63550536
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field 金属材料(含表面処理・腐食防食)
Research InstitutionKYOTO UNIVERSITY

Principal Investigator

MAKI Tadashi  Kyoto Univ., Faculty of Eng., Professor, 工学部, 教授 (10026247)

Co-Investigator(Kenkyū-buntansha) TSUZAKI Kaneaki  Kyoto Univ., Faculty of Eng., Research Associate., 工学部, 助手 (40179990)
Project Period (FY) 1988 – 1989
Project Status Completed (Fiscal Year 1989)
Budget Amount *help
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1989: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1988: ¥1,500,000 (Direct Cost: ¥1,500,000)
KeywordsSuperplasticity / Dynamic recrystallization / Duplex stainless steel / High carbon steel / Grain boundary sliding / Low-angle boundary / High-angle boundary / 2相微細組織 / 亜粒界
Research Abstract

Structural change during superplastic flow has been studied in order to clarify the deformation mechanism and the role of dynamic recrystallization in superplasticity of a duplex stainless steel (Fe-25%Cr-7%Ni-3%Mo) and a high carbon steel (Fe-1%C-1.4%Cr). Main results obtained are as follows.
1. A microduplex structure with fine ferrite and austenite grains (about lmum) was obtained in the duplex stainless steel by thermomechamical processing. Ferrite matrix before tensile deformation were subgrains and ferrite/ferrite boundaries were low-angle ones and unsuitable for grain boundary sliding. The specimen with this microduplex structure showed, however, over 1700% elongation at 1273K and epsilon=1.7x10^<-2>/s. In the early stage of deformation, dynamic recrystallization took place in ferrite matrix and ferrite/ferrite boundaries changed to high-angle ones. After the recrystallization of ferrite, dislocations were scarcely observed in both phases of ferrite and austenite during deformation, indicating that grain boundary sliding is the predominant mode of superplastic flow in the present steel. It was concluded that the role of dynamic recrystallization is to make the structure suitable for grain boundary sliding in the early stage of deformation.
2. A fine ferrite grain structure with spheroidized cementite particles was obtained in the high carbon steel by warm rolling by 90% at 923K after pearlite transformation. Most of ferrite grains were subgrains even after 90% warm rolling. After superplastic deformation, ferrite grain boundaries were high-angle ones. This result suggests that ferrite phase dynamically recrystallized and became the suitable structure for grain boundary sliding during the deformation.

Report

(3 results)
  • 1989 Annual Research Report   Final Research Report Summary
  • 1988 Annual Research Report
  • Research Products

    (3 results)

All Other

All Publications (3 results)

  • [Publications] 津崎兼彰: "2相ステンレス鋼の高速超塑性と動的再結晶の役割" 日本金属学会誌.

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] K. Tsuzaki, H. Matsuyama, M. Nagao and T. Maki: "High strain rate superplasticity and role of dynamic recrystallization in a duplex stainless steel." J. Jpn. Inst. Metals.

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] 津崎兼彰: "2相ステンレス鋼の高速超塑性と動的再結晶の役割" 日本金属学会誌.

    • Related Report
      1989 Annual Research Report

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Published: 1988-04-01   Modified: 2016-04-21  

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