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Prediction of Tensile Strength of High-Nitrogen 18Mn-18Cr Austenitic Steels for Generator Retaining Ring

발전기용 오스테나이트계 18Mn-18Cr 고질소강의 제조와 인장강도 예측

  • Hwang, Byoungchul (Department of Materials Science and Engineering, Seoul National University of Science and Technology) ;
  • Lee, Tae-Ho (Advanced Metallic Materials Division, Korea Institute of Materials Science)
  • 황병철 (서울과학기술대학교 신소재공학과) ;
  • 이태호 (한국기계연구원 부설 재료연구소 신금속연구본부)
  • Received : 2013.08.10
  • Accepted : 2013.08.26
  • Published : 2013.09.27

Abstract

Over the past few decades, high-nitrogen austenitic steels have steadily received greater attention since they provide a unique combination of high strength and ductility, good corrosion resistance, and non-magnetic properties. Recently, highnitrogen 18Mn-18Cr austenitic steels with enhanced strength have been developed and widely used for generator retaining rings in order to prevent the copper wiring from being displaced by the centrifugal forces occurring during high-speed rotation. The high-nitrogen austenitic steels for generator retaining ring should be expanded at room temperature and then stress relief annealed at around $400^{\circ}C$ to achieve the required mechanical properties. In this study, four kinds of high-nitrogen 18Mn-18Cr austenitic steels with different nitrogen content were fabricated by using a pressurized vacuum induction melting furnace, and then the effects of nitrogen content, cold working, and stress relieving on tensile properties were investigated. The yield and tensile strengths increased proportionally with increasing nitrogen content and cold working, and they further increased after stress relieving treatment. Based on these results, a semi-empirical equation was proposed to predict the tensile strength of highnitrogen 18Mn-18Cr austenitic steels for generator retaining rings. It will be a useful for the effective fabrication of high-nitrogen 18Mn-18Cr austenitic steels for generator retaining rings with the required tensile properties.

Keywords

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