Nitrogen bearing martensitic stainless steels are known for their high mechanical properties and good corrosion resistance. High nitrogen contents can be introduced in stainless steels by high temperature nitriding treatments. If the thermo-chemical treatment is performed in bulk specimens, cases with up to 0.8%N and 1.2 mm depth can be achieved.

In order to evaluate the wear resistance of high temperature nitrided martensitic stainless steels, slurry wear tests were performed in the case hardened (nitrogen) specimens. The results were compared with those obtained for conventional AISI 410 and ASI 420 martensitic stainless steels.

Nitriding treatments were carried out in a tubular furnace under 0.15-0.25 MPa pressure high purity nitrogen atmosphere, at 1273-1473K during 6 hours. After the treatment the samples were cooled down in a water jacked cooling zone

The slurry wear test simulates actual operating conditions on hydraulic turbines and pumping systems, where erosive wear caused by abrasive particles in aqueous solutions is significant. Temperature, pH, solids concentration and sample velocity were controlled during the test. The specimens were attached to aluminum holders inside the slurry. Changes in mass and roughness of the specimens were registered after all the experiments. Wear surface analysis was performed in a SEM and the changes were related to wear mechanisms acting on the surface.

The results showed that nitrogen improves the resistance of martensitic stainless steels to slurry erosion.