A comparative study on the fretting wear of steam generator tubes in korean power plants

Abstract Fretting wear tests were performed to evaluate wear properties of steam generator (SG) tubes in room temperature water. In this study, wear experiments have been conducted at various loads and sliding amplitudes using five material conditions; the combination of SG tubes (Inconel 600HTMA, 690TT and Alloy 800) and their supports (405, 409 ferritic and 410 martensitic stainless steels) are being operated at Korean nuclear power plants. Experimental results show that wear coefficient of a work-rate model in Alloy 800 against 410 stainless steel is the highest (67×10 −15  Pa −1 ), whereas that in Inconel 690TT against 409 stainless steel is the lowest (18×10 −15  Pa −1 ). Based on the observation of the deformation layer using SEM, both Inconel 600HTMA and 690TT show very similar wear mechanisms. However, the wear mechanism of Alloy 800 is somewhat different. In the case of Inconel 600HTMA and 690TT, almost wear particles were released in the form of thin plate from deformation layers. However, wear particles in Alloy 800 were released both from plastic flow generated by severe deformation and from third body abrasion during fretting wear, which related to a lower wear-resistance compared to the Inconel 600HTMA and 690TT. The details of microstructural investigation show that Inconel 690TT has more resistance to fretting wear because its small cell structure could easily accommodate large strain on worn surface. In addition, the relationship between the wear coefficients of the work-rate model and the mechanical properties of deformation layers is suggested.