Mechanisms of stainless steels erosion by water droplets

Our study deals with rain erosion of metal, which concerns aeronautic industries. The erosion resistance of AISI301 and MLX17, austenitic and martensitic stainless steels respectively, has been appraised thanks to a pulsated water jet device. Moreover, the influence of hardness has been evaluated thanks to hard-rolling plates. The tests of erosion are 10 million impacts for each material with 225 m/s impact velocity to obtain sufficient wear volume. The kinetics has been assessed by stopping the test every million impacts, making possible replicas of defects with fast precision resin. An in-service eroded sample has been analysed for comparison purpose. Finally, the best erosion resistance among the tested materials was shown by the hard-rolled austenitic stainless steel, since erosion resistance increases with work hardening. Sample MLX17 was not as resistant as hard-rolled AISI301 despite better mechanical properties. This would be due to a more brittle behaviour of martensite than that of austenite. Surface observations of tested samples reveal inter-granular cracks and fatigue defects similar to those observed in-service. Finally the erosion mechanisms consist of plastic deformation, work hardening, initiation and growing of cracks and, finally, fatigue spalling.