Abstract: In order to improve the service life of H13 steel wear-resistant guide rail of the TDO, the guide rail with a core hardness of about 300 HV0.3 was treated by laser surface quenching, gas nitriding, laser surface quenching+gas nitriding composite treatment process respectively for surface strengthening, and then the wear resistance was compared and analyzed based on surface hardness, hardening layer depth and hardness gradient. The results show that the gas nitriding can significantly improve the surface hardness (>980 HV0.3), but the depth of the hardened layer is shallow (only about 0.27 mm). The laser surface quenching increases the depth of the hardened layer by several times (up to about 0.7 mm), but the surface hardness is lower than that after the gas nitriding (up to 764 HV0.3). By the laser surface quenching (P=2500 W, v=4 mm/s) followed by gas nitriding (at 540 ℃ for 25 h) composite treatment, the advantages of both the processes can be combined to achieve higher surface hardness (>980 HV0.3) and increase the hardening layer depth (up to 0.61-0.67 mm), and effectively improve the wear resistance of the guide rail.

Key words: H13 steel, gas nitriding, laser surface quenching, TDO, guide rail, surface strengthening