Evaluation of electrochemical effects on impact fretting wear of Ni based alloy 690

Abstract

In order to clarify the effect of thermal treatment on wear resistance and on corrosion resistance of Ni based alloy 690 which employed to pipe material of steam generator in pressurized water reactors, impact fretting wear properties and polarization characteristics were investigated using an impact fretting test rig which is connected to a potentiostat and can control load and amplitude with high precision. As a result, it was confirmed that the thermal treatments improved the corrosion resistance on the polarization test, but it had almost no effect on the impact fretting wear. Since the current obtained by the potentiostat, the anodic dissolution (corrosion) at the fresh surface had a significant effect on impact fretting wear under anodic potential. Furthermore, according to Faraday's law, the dissolution volume of impact fretting test Vf estimated from the current obtained by the potentiostat almost agreed with the wear volume Vg calculated from the surface geometry.

Keywords

• pwr
• steam generator
• heat transfer tube
• ni based alloy 690
• thermal treatment
• impact fretting
• fretting
• corrosion
• wear