Laser deposited TiC/H13 tool steel composite coatings and their erosion resistance

The present work studies the synthesis and performance of TiC/H13 tool steel composite coatings obtained by the laser deposition technique. The effect of laser beam-scanning speeds and the concentrations of TiC in injected powder on the morphologies and microstructures of deposited beads are investigated. The results show that the beam-scanning speeds affect the size and morphology of the beads. During laser processing, TiC melts, and decomposes, and subsequently, a number of fine TiC precipitates form during cooling that are uniformly distributed in the steel matrix. The amount of injected TiC has a strong influence on the morphology and size of the fine TiC precipitates. Unlike ductile steel and hard carbide coatings, the TiC reinforced steel matrix composite coatings exhibit a decreased slurry erosion resistance at intermediate impact angles in the range from 0 to 90°; while at both smaller and larger impact angles, they show an increased slurry erosion resistance. By increasing the concentration of TiC in the composite coatings, their erosion resistance decreases. The composite coating with 40 vol.% TiC shows an excellent erosion resistance at high impact angles.