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pISSN : 1598-706X / eISSN : 2288-8381


한국주조공학회지 (12권3호 230-237)

Changes of Microstructure due to Mn Element and Pearlite-Bainite Transformation Treatment in Ductile Cast Iron

구상흑연주철의 Mn성분과 펄라이트-베이나이트변태 처리의 변화가 미세조직에 미치는 영향

Kwan-Soo Suh, Byung-Joon Ye

Kyungpook National University


The purpose of present investigation is to obtain ductile cast iron with ferrite-bainite matrix by pearlite-bainite transformation treatment. Ductile cast irons having three kinds of Mn ampunt had been manufactured. Mn increased pearlite volume fraction iin as-cast ductile cast iron. Ductile cast irons of different pearlite fraction were austenitized at 875℃ for 230-350 sec or 925℃ for 130-170 sec followed by austempering at 300℃ or 400℃ for the various periods of time from 5 to 30 min. When specimen was austenitixed for 130 sec at 925℃ and for 230 sec at 875℃, pearlite was transformed into austenite. Bainite around graphite was found at 925℃ for 170 sec. Bainite in grain boundary of ferrite was happened at 875℃ for 350 sec. During the austempering process, acicular bainite was precipitated at 300℃ and lath bainite was precipitated at 400℃. Increment in manganese content restrained bainitic transformation. Retained austenie was of little quantity.