Effects of amplitude and frequency on the wear mode change of Inconel 690 SG tube mated with SUS 409

Steam generator (SG) tubes in certain types of nuclear power plants experience flow-induced vibrations that can result in fretting wear. The wear mode under these conditions can change with wear variables. Using a custom-designed fretting test apparatus, the effects of amplitude and frequency on wear mode changes for Inconel 690 SG tubes mated with SUS 409 were investigated. Changes in the wear mode were found by using periodic measurements of weight loss to calculate wear coefficients. The wear mode was observed to change from stick to gross slip and sliding as amplitude increased from 25 μm to 300 μm. However, the wear mode did not change with increasing frequency or testing duration within the range of applied conditions.