Structure and tribological behavior of surface layer of laser modified X40CrMoV5-1 steel

Purpose: The paper presents the effect of alloying with WC, TaC and TiC on structure and mechanical properties of the X40CrMoV5-1 steel surface layer using the HPDL (High Power Diode Laser). Design/methodology/approach: The microstructure of the alloyed layers which were formed on the surface of the investigated hot work steel was examined using optical microscope. The tribological wear relationships using pin-on-disc test were specified for surface layers subject to laser treatment, determining the friction coefficient, and mass loss of the investigated surfaces. X-ray diffraction (XRD) technique was used to investigate crystalline structure and phases in the layers. Findings: The metallographic investigations on light microscope show that during alloying the X40CrMoV5-1 hot work tool steel with the WC, TaC and TiC powder layer the obtained run face is characteristic of the high roughness, multiple pores, irregularity, and flashes at the borders. The changes of the surface layers hardness formed as a result of remelting and alloying with ceramic powders containing carbides are accompanied with the increased tribological properties. Research limitations/implications: In order to evaluate with more detail the possibility of applying these surface layers in tools, further investigations should be concentrated on the determination of the thermal fatigue resistance of the layers. Practical implications: The alloyed layers which were formed on the surface of the hot work steel have shown significant improvement. Good properties of the laser treatment make these layers suitable for various technical and industrial applications. Originality/value: Structural and tribological behaviour of surface layer achieved by alloying and remelting using high diode power laser and selected ceramic powders were compared.