Pearlite growth kinetics in Fe-C-Mn eutectoid steels

Fe-C-Mn共析鋼におけるパーライト成長の速度論

Zhang, Y.*; 梅田 岳昌*; 宮本 吾郎*; 古原 忠*; 諸岡 聡  

Zhang, Y.*; Umeda, Takemasa*; Miyamoto, Goro*; Furuhara, Tadashi*; Morooka, Satoshi

Essential understanding of the pearlite growth kinetics is important to predict the lamellar spacing and the resultant mechanical properties of pearlitic steels. In this study, through quantitatively analyzing the microstructural features in the vicinity of pearlite growth interface, the influence of these factors and the underlying thermodynamics of pearlite growth kinetics were clarified. The pearlite growth rate and lamellar spacing were measured based on the microstructural observation via optical microscopy and scanning electron microscopy, respectively. Three-dimensional atom probe (3DAP) was used to analyze the elemental distribution in the vicinity of pearlite growth front, whereas in-situ neutron diffraction at elevated temperatures was performed at J-PARC, BL19 (TAKUMI) to quantify the elastic strain generated during pearlite transformation. Based on the proposed thermodynamic model, the influence of various factors on the pearlite growth kinetics is estimated using the experimental results obtained in this study. It was found that in most transformation conditions, solute drag effects caused by Mn interfacial segregation have the largest contribution in retarding the pearlite growth rate. In contrast, the magnitude of elastic strain in pearlite measured by neutron diffraction is quite small, which marginally affects the pearlite growth kinetics.