Effects of Rare Earth on the Microstructure and Mechanical Properties of a Pearlitic Steel Wire Rod

The effects of rare earth (RE) on the microstructure and mechanical properties of a pearlitic steel wire rod are investigated under the dual-low-oxygen condition. The results show that the wire rods with different RE contents all have pearlite microstructure. As RE content increases from 0 to 310 ppm, the pearlite substructures such as interlamellar spacing, pearlite colony size, and ferrite grain size decrease remarkably, indicating that the nucleation and growth behavior of pearlite change. This is attributed to the combined effects of stimulating nucleation by a large number of micrometer-scale RE-containing inclusions and decreased carbon diffusion due to RE in solution. As a result, the changes in microstructure lead to simultaneous enhancement of strength, plasticity, impact toughness, and microhardness of pearlite wire rod, demonstrating that adding appropriate content of RE under the dual-low-oxygen condition is an effective alloying method to optimize the microstructure and mechanical properties of pearlitic steel wire rod. Under the dual-low-oxygen condition, because of the comprehensive effects of stimulating nucleation by rare earth (RE)-containing inclusions and lowering carbon diffusion by RE in solution, the addition of RE decreases the interlamellar spacing, pearlite colony size, and ferrite grain size of a pearlitic steel, which increase the strength, plasticity, and impact toughness of pearlitic steel simultaneously.image (c) 2023 WILEY-VCH GmbH