Crystallisation mechanism of laser alloyed gradient layer on tool steel

Purpose: The objective of the present work was to study the modification of the microstructure of hot-work tool steel X40CrMoV5-1 during the surface modifying by means of laser technology. Design/methodology/approach: The structural mechanism of surface layer development was determined and the effect of alloying parameters and thickness of paste layer applied onto the steel surface on structure refinement and influence of these factors on the crystallisation mechanism of surface layer was studied. Findings: development of the surface layer was observed in which one can distinguish the remelted zone, heat-affected zone and the transient zone. The finite grained, dendritic structure occurs in the remelted and alloyed zone with the crystallization direction connected with the dynamical heat abstraction from the laser beam influence zone. The X40CrMoV5-1 conventionally heat treated steel was used as reference material. Practical implications: Laser surface modification has the important cognitive significance and gives grounds to the practical employment of these technologies for forming the surfaces of new tools and regeneration of the used ones. Originality/value: The outcome of the research is an investigation showing the structural mechanisms accompanying laser alloying.