FEATURES OF THE INFLUENCE OF CHEMICAL COMPOSITION ON THE FORMATION OF MECHANICAL PROPERTIES IN LOW-CARBON Cr-Mo-V WELDING STEELS

Abstract

The influence of the chemical composition of low-carbon welding steels with a Cr-Mn-Si-Mo-V alloying system and additional boron microalloying on the mechanical properties of steel wire rod was analyzed under constant parameters of the thermomechanical treatment mode. Based on a regression analysis of 28 melts, predictive models were developed to estimate changes in tensile strength, yield strength, and reduction of area in the steel wire rod. The physicochemical equivalent of the metal system’s charge state and the boron content both most closely correlated with the mechanical property set of the steels were selected as independent variables in the models. It was established that a potential method to further reduce strength and increase the plastic properties of steel wire rod is to decrease the content of alloying elements, primarily carbon and manganese, within the compositional range of the steel grade. An increase in boron concentration leads to higher strength and reduced plasticity of the metal, presumably due to a reduction in the average ferrite grain size. However, boron microalloying has a beneficial effect on the deformability of the wire rod during subsequent wire drawing, as it binds atomic nitrogen into nitrides and prevents deformation aging of the metal during cold plastic deformation.