高 Mn オーステナイト鋼の恒温変態に伴う組織変化

概要

論文の詳細を見る
Microstructural change during isothermal aging has been investigated in 13%Mn-0.9%C and 22%Mn-0.6%C steels by means of optical and electron microscopy and X-ray diffractometry. High manganese austenitic steels undergo three kinds of reactions during isothermal aging ; (1) grain boundary precipitation of carbide, (2) precipitation of platelet carbide within austenite (γ) grains and (3) formation of lamellar structure through eutectoid transformation (γ⟶ferrite (α)+carbide). In 13%Mn-0.9%C steel, all of the reactions occur and the carbide concerning the reactions is M_3C in any case. On the other hand, in 22%Mn-0.6%C steel, only two of them occur ; grain boundary precipitation of M_<23>C_6 carbide (not M_3C) and the eutectoid transformation (γ⟶α+M_3C). Besides, both of the two reactions in 22%Mn-0.6%C steel were effectively suppressed due to the chemical composition ; high Mn and low C content. Eutectoid transformation proceeds by being supplied carbon from untransformed γ, so that this results in the shortage of carbon in untransformed γ during isothermal aging and the γ phase undergoes γ⟶ε (hcp) martensitic transformation on the following cooling.
社団法人日本鉄鋼協会の論文
1998-04-01