Effect of composition and processing parameters on the formation of nano-bainite in advanced high strength steels

Ilana Timokhina, Hossein Beladi, Xiang Xiong, Peter Hodgson

Research output: Contribution to journalArticleResearchpeer-review


The nano-bainitic microstructures were compared in a 0.79C-1.5Si-1.98Mn-0.24Mo-1.06Al (wt%) steel after isothermal heat-treatment and a Fe-0.2C-1.5Mn-1.2Si-0.3Mo-0.6Al-0.02Nb (wt%) steel after controlled thermomechanical processing.The microstructure for both steels consisted of bainite.The microstructural characteristics of bainite,such as the morphology of the nano-bainite and thicknesses of bainitic ferrite and retained austenite layers,as a function of steel composition and processing was studied using transmission electron microscopy (TEM).It was found that the nano-bainitic structure can be formed in the low alloy steel through thermomechanical processing.Atom probe tomography (APT) was employed as a powerful technique to determine local composition distributions in three dimensions with atomic resolution.The important conclusions from the APT research were that the carbon content of bainitic ferrite is higher than expected from paraequilibrium level of carbon in ferrite for both steels and that Fe-C clusters and fine particles are formed in the bainitic ferrite in both steels despite the high level of Si.
Original languageEnglish
Pages (from-to)238-241
Number of pages4
JournalJournal of Iron and Steel Research International
Issue numberS1
Publication statusPublished - 2011


  • nano-bainite
  • transmission electron microscopy
  • atom probe tomography
  • carbon content

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