Characterization and performance of laser alloyed commercial tool steels

Purpose: The purpose of this research paper is investigated influence of carbides particle on the functional properties of surface layers. Design/methodology/approach: The experiments were made on specimens made from the HS6-5-3-8 high speed steel remelted and alloyed. The technological part of this work was made using the HPDL Rofin DL 020. Therefore all experiments were made at the constant remelting rate, varying the laser beam power in the range from 0.7 to 2.5 kW. It was established experimentally that the argon blow-in with the flow rate of 20 l/ min through the 12 mm circular nozzle oppositely directed in respect to the remelting direction provides full remelting zone protection. Findings: The structure of the solidified material after the laser remelting is characterized by the diversified morphology connected with the multiple changes of the crystal growth direction from little dendrites to tiny equiaxed grains in the near-surface zone. The main axes of the dendrites are directed according to the heat abstraction directions on the border of the solid and liquid phases with the carbides’ clusters arranged according to the whirls caused by a convectional movement in the pool of the metallic liquid as well as partly unremelted conglomerates WC as a melting material in the middle area of the remelted zone. Research limitations/implications: The material behavior for the HPDL processing has been found to be different from the other high-power lasers in the following aspects: fewer cracks and less spallation for surface glazing/sealing, more uniform melt/heating zones, smoother surface, better beam absorption for metallic materials, more consistent and repeatable. Practical implications: The research results indicate to the feasibility and purposefulness of the practical use of remelting and alloying with the WC particles using the high power diode laser for manufacturing and regeneration of various tools from the HS6-5-3-8 high speed steel. Originality/value: The laser treatment as a part of the new generation techniques applied in metal surface technology.