Effect of Cr Contents on Microstructure and Properties of Hot Rolling Strip of 65Mn High Carbon Steel

Hot rolling strip of 65Mn high carbon steel was prepared with Cr contents (mass fraction) of 0.01%, 0.10%, 0.13% and 0.16%, respectively. The microstructure and grain size of the samples with different Cr contents were analyzed by metallographic microscope, and the mechanical properties of the samples were also tested. The results show that the spacing of the pearlitic laminates could be refined and the reticular ferrite could be weakened by adding Cr element in the 65Mn steel. When increasing Cr contents from 0.01% to 0.16% in 65Mn steel, the grade of grain size increased from 8.0 to 8.8, and the tensile strength increased from 822 MPa to 999 MPa, while the percentage elongation after fracture decreased from 29% to 22%. Moreover, when the Cr contents were less than 0.13%, microstructure and mechanical properties of the materials were influenced by the Cr contents significantly. The comprehensive mechanical properties of 65Mn high carbon steel were affected by the element of Cr with the effects of grain refining and secondary phase Cr₃C separating.