Surface modification of the X40CrMoV5-1 steel by laser alloying and PVD coatings deposition

Purpose: The paper presents the influence of alloying with NbC powder by the use of a high-power diode laser and TiAlN, AlSiCrN and TiCN gradient coatings deposition by PVD process on microstructure and hardness of the X40CrMoV5-1 steel surface layer. Design/methodology/approach: Microstructure was characterised using optical metallography, scanning and transmission electron microscopy. Findings: In the effect of laser alloying with powders of carbide NbC occurs size reduction of microstructure as well as dispersion hardening through fused in but partially dissolved carbides and consolidation through enrichment of surface layer in alloying additions coming from dissolving carbides. The structure of the PVD coatings consisted of fine crystallites while their average size fitted within the range of 15-50 nm, depending on the coating type. The coatings demonstrated columnar structure. Research limitations/implications: It is necessary to continue the research to determine alloying parameters for demanded properties of hot work tool steels surface layers. Further investigations should be concentrated on the determination of the thermal fatigue resistance of the layers. Practical implications: Good properties of the PVD coatings and the laser treatment make these layers suitable for various technical and industrial applications. Originality/value: Laser alloying by using different carbide powders and HPDL laser is a new way to improve the structure and mechanical properties of the hot work tool steels.