Erosion wear behavior of laser clad surfaces of low carbon austenitic steel

Abstract

Austenitic steel surfaces are laser cladded using a 4 kW continuous wave CO 2 laser with coaxial powder feeding nozzle to investigate the improvement in slurry erosion characteristics. Colmonoy-6 and Inconel-625 are cladded on AISI 316L steel and AISI 304L steel, respectively by laser cladding. Initially, single-pass clad track is overlaid to optimize the laser processing parameters, namely scanning speed and powder feed rate to obtained a sound clad. Minimum cracks, porosity and distortion were found at scanning speed of 0.1 m/min and powder feed rate of 12 g/min. For these parameters, the dilution was 17.33% for Colmonoy-6 and 40% for Inconel-625. To clad large surface area, the optimized laser processing parameters were used to deposit the clad tracks with 60% overlap. Maximum surface hardness of 746 VHN is obtained in case of Colmonoy-6 clad on AISI 316L steel and is 352 VHN in case of Inconel-625 clad on AISI 304L steel. EDAX analysis shows higher degree of mixing of substrate material in the clad pool of Inconel-625 than Colmonoy-6. The results of slurry erosion test of Colmonoy-6 clad surface have shown improvement in erosion resistance of the order of 1.75–4.5 times of the substrate AISI 316L steel at all impact angles and the maximum wear angle has also increased which can be attributed to the increase in the surface hardness. However, Inconel-625 laser clad surface has shown little improvement in erosion resistance of the substrate AISI 304L steel at shallow impact angles with no significant improvement at normal impact condition. The SEM micrographs of worn out Colmonoy-6 clad surfaces at shallow impact angles show that the material is removed mainly by micro-cutting which increases with increase in the impact angle.