The Effect of Microalloying (Nb, V) and Interstitial (C, N) Elements on Mechanical Properties of Microalloyed Steels

The microalloying elements such as Nb, V are added to control the microstructure and mechanical properties of microalloyed (HSLA) steels. High chemical affinity of these elements for interstitials (N, C) results in precipitation of binary compound, nitrides and carbides and products of their mutual solubility – carbonitrides. The chemical composition of austenite, as well as the content and geometric parameters of undissolved precipitates inhibiting the growth of austenite grains is important for predicting the microstructure, and thus the mechanical properties of the material. Proper selection of the chemical composition of the steel makes it possible to achieve the required properties of the steel at the lowest possible manufacturing cost. The developed numerical model of carbonitrides precipitation process was used to simulate and predict the mechanical properties of HSLA steels. The effect of Nb and V content to change the yield strength of these steels was described. Some comparison with literature was done.