Three-dimensional Morphology and Growth Kinetics of Intragranular Ferrite Idiomorphs Formed in Association with Inclusions in an Fe-C-Mn Alloy

Abstract

The three-dimensional (3-D) morphology and growth kinetics of intragranular ferrite idiomorphs formed in association with MnS(+VN) inclusions were studied in an Fe-C-Mn alloy. Ferrite idiomorphs began to be formed at a temperature 40°C lower than the grain boundary allotriomorphs, and the highest temperature of the formation of intragranular ferrite plates was 60°C below the Widmanstatten start temperature of grain boundary sideplates (Ws). The 3-D shape of ferrite idiomorphs was more equiaxed than grain boundary allotriomorphs. Measured growth rates were smaller than those calculated assuming spherical growth, similar to those of grain boundary allotriomorphs previously reported. The possible reasons for the retardation of growth, e.g. deprivation of carbon supersaturation by grain boundary ferrite allotriomorphs and solute drag etc., are discussed.