Determination of the fretting maps on Incoloy 800 steam generator tubes against AISI 420 steel

Running Condition and Material Response Fretting Maps of Incoloy 800 steam generator tubes against AISI 420 martensitic steel were determined. Tests were performed in air at room temperature using displacement amplitudes between 5 and 50 µm and normal contact loads from 10 to 20 N to a total of 106 cycles. The results were compared with previously obtained maps of Incoloy 800 against austenitic AISI 304 L steel pads. For equivalent relative displacements and contact loads the maps presented the same fretting regimes and damage mechanisms being the Archard-wear coefficients greater using AISI 420 pads. Detached debris was composed of agglomerates of nanoparticles of (Ni,Fe)(Fe,Cr)2O4. The presence of Cr in the steel pad promotes the formation of spinel structures.