LASER PROCESSING OF CAST IRON FOR ENHANCED EROSION RESISTANCE.

Abstract

The surfaces of nodular and gray cast iron have been modified by CO//2 laser processing for enhanced hardness and erosion resistance. Control of the near-surface microstructure was achieved primarily by controlling resolidification of the laser melted layer through variations in laser beam/target interaction time and beam power density. Typical interaction times and power densities used were 5 msec and 500 kW/cm**2. Two basic kinds of microstructure can be produced - a feathery microstructure with high hardness (up to 1245 HV) and a dendritic microstructure with a metastable, fully austenitic matrix and lower hardness (600 to 800 HV). Erosion testing was done using slurries of SiO//2 or SiC in water.