Insight into the effect of Nb microalloying on the microstructure–property relationship of a novel wire rod

Abstract

The microstructure–property relationship of a novel wire rod was investigated after Nb microalloying. The tensile properties were significantly improved. The impact of Nb on pearlitic transformation, residual stress, residual strain, and microstructure uniformity was discussed in this paper. By changing the alloy phase diagram, Nb microalloying improved the undercooling of the pearlitic transformation, resulting in finer lamellar spacing. Residual stresses and residual strain as different kinds of deformation energy storage satisfied the water-bed effect after Nb microalloying. After hot rolling, the residual stresses of the Nb-bearing wire rod were reduced while the residual strains increased. The increase in deformation between the transverse and longitudinal sections (TS and LS) during hot rolling led to an increase in residual strain and a decrease in residual stress in wire rods. Furthermore, the uniform grains and more random texture observed after Nb microalloying increased the microstructure uniformity of wire rods. This phenomenon was thought to be caused by the precipitation of Nb carbides during hot rolling.

Keywords

• Wire rod
• Nb microalloying
• Tensile properties
• Residual strain
• Residual stress
• Microstructure uniformity