Study on the Effect of Normal Loads on the Fretting Wear Performance of Zr-4 Alloy Tubes Under Three Fretting Modes

Abstract

A self-developed tube-to-tube contact fretting wear tester was used to conduct fretting wear tests on Zr-4 fuel rods in pressurized water reactors of nuclear power plants under three fretting wear modes (tangential, radial, and dual-motion fretting) with different normal loads [F_n = 15–25 (20), 30–50 (40), and 45–75 (60) N]. The test results show that the normal load and fretting wear mode have a significant effect on the fretting wear behaviors of Zr-4 alloy tube. Comparing the different fretting wear modes, the contact surface is almost coordinated by elastic deformation under the radial fretting wear mode, with the slightest damage; for tangential fretting wear mode, the damage mechanism is mainly fatigue wear and delamination; the most severe damage was observed under the dual-motion fretting wear mode, where the wear mechanism consisted of a combination of delamination, abrasive wear, adhesive wear, and oxidative wear.