Precipitation behavior and kinetics in Nb-V-bearing low-carbon steel

The chemical composition and lattice parameter of the nanometer-sized carbides in ferrite of Nb-V bearing low-carbon steel were studied by high resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy. The results indicate that the average size of the carbides increased with increase in isothermal holding time. V was found to be gradually incorporated into NbC lattice to form a complex (NbxV1-x)C particle during precipitation and the atomic ratio of V/Nb gradually increased during coarsening, which leads to a decrease in the lattice parameter of carbide and reduces the misfit strain between the carbide and ferrite matrix, resulting in acceleration of precipitation kinetics. (C) 2016 Elsevier B.V. All rights reserved.