Toughening of Fe-based laser-clad alloy coating

An investigation is reported on crack-free laser clad Fe-based alloy by use of biaxial powder feeding shielded with argon gas. The microstructure and phase structure of the coating were studied, and mechanical properties were analyzed through hardness, tension strength and wear resistance of the coating. Microstructure analysis showed that there was retained austenite with spherical particles distributed therein in the interdendritic and nearby grain boundary regions. The mechanical test results showed that net-like distributed retained austenite in the interdendritic region had certain toughening effect through blunting crack-tip. Under wear condition of high sliding speed and high loading, the wear resistance of the coating with net-like retained austenite was much higher than that of the coating with some discontinuous carbide network or carbide blocks. The results showed that toughening of laser clad Fe-based alloy with high hardness over 850 HV could be achieved by modifying interdendritic phases from net-like carbide to net-like austenite with spherical particles.