Effect of inclusions on the formation of acicular ferrite in Ti-bearing non quenched-and-tempered steel

Ying Yang1,2), Chaobin Lai1,3), Fuming Wang1), Zhanbing Yang1), and Bo Song1) 1) Metallurgical and Ecological Engineering School, University of Science and Technology Beijing, Beijing 100083, China 2) Technology Centre, Anshan Iron and Steel Group Corporation, Anshan 114009, China 3) Technology Centre, Xinyu Iron and Steel Group, Xinyu 336501, China

摘 要：Nucleation of acicular ferrite and its influence factors in non quenched-and-tempered steel was studied by using TEM and thermodynamic calculation. The results show that the complex particles with a center made of Ti oxide, Al2O3, and silicate and an outside made of a small quantity of mixture of TiN and MnS are able to act as ferrite nucleation nuclei. The acicular ferrite percent- age changes little with Ti. When the oxygen content was 80 ppm, the volume percentage of acicular ferrite decreased due to an in- crease in allotriomorphic ferrite. The larger the cooling rate and the shorter the incubation time, the finer the titanium oxide and the higher the nucleation ratio of acicular ferrite.

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