The effect of subsurface deformation on the wear behavior of steam generator tube materials

Fretting wear behavior of steam generator (SG) tube materials (Inconel 600MA and 690TT) against ferritic stainless steels was investigated in a room temperature water environment. The results indicated that the fretting wear rate and wear coefficient (K) in a work-rate model of Inconel 600MA were higher than those of Inconel 690TT with increasing normal loads and sliding amplitudes. From the results of scanning electron microscopy (SEM) observation, there was little evidence of particle agglomeration on the worn surfaces, while wear particles were released in the form of thin plates, which were generated from deformation substructures formed by severe plastic deformation during fretting wear. Therefore, the wear rates of SG tube materials in the room temperature water are closely related with plastic deformation behavior on contact surfaces. In subsurface layer, wear particle size seems to be determined by cell-structure thickness and closely related to the difference of stacking fault energy (SFE) of tube materials through chromium contents. Inconel 690TT showed lower wear rate because it should have relatively smaller cells due to lower SFE than Inconel 600MA and in turn may easily accommodate large strains.