Microstructure and mechanical properties of austempered medium carbon steels

Takeshi Suzuki, Yoshiki Ono, Goro Miyamoto, Tadashi Furuhara

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


Microstructures and mechanical properties for medium carbon steels including practical spring steels austempered at 400°C and 300°C were investigated. The larger strain was applied, the larger the fraction of retained au stem te became martensite through strain induced transformation. 0.2% proof stress was increased by the increase of the fraction of bainitic ferrite. Uniform elongation was increased by increasing the fraction of retained austenite. Good strength-ductility balance with tensile stress over 1800MPa for high strength spring was achieved in austempered SUP12 at 300°C composed of three phases of retained austenite, martensite and lower bainite.

Original languageEnglish
Pages (from-to)26-33
Number of pages8
JournalTetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan
Issue number1
Publication statusPublished - 2011


  • Austempering
  • Bainite
  • Martensite
  • Mechanical property
  • Medium carbon steel
  • Retained austenite
  • Spring steel


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