Microstructure and Properties of a Laser Hardened Non-composite Rolling Mill Liner
Mill liners play a role in protecting mill stand. In order to change the traditional status that rolling mill liner can not be manufactured with a single material, laser transformation hardening was carried out with a CO2 laser on 45 steel surfaces and produced a new type non-composite liner. The microstructure and properties were researched by means of a scanning electron microscope (SEM), X-ray diffraction (XRD), microhardness tester, abrasive wear testing machine and electrochemical workstation. The results indicate that the microstructure of the laser transformation hardened layer fine and homogeneous, mainly composed of Fe3C, Fe-Cr and Cr3C2, the hardness is about three-times that of the substrate, the relative wear resistance increased significantly, which can reached the technical requirements liner needed. The laser transformation hardened layer plays an important protective role in 3.5% NaCl environment.
Keywords: CO2 laser, 45 steel, laser hardening, non-composite rolling mill liner, microstructure, microhardness, wear resistance