Fretting Wear Behavior Of Inconel690at High-Temperature Nitrogen

Steam generator(SG) tube is an important components in nuclear power plants. The fracture of the steam generator tube induced by fretting wear is one of the early main failure reasons. Investigation on fretting wear and damage mechanisms of steam generator (SG) tube material Inconel690at high temperature and high-temperature nitrogen is of great importance to improve the life and reliability of steam generator (SG) tube. PLINT high temperature fretting wear testing machine was improved from tangential fretting to tangential and radial two-way complex fretting, and then better simulated the complex fretting damage of components in actual environment, thereby overcoming the original singularity of tangential fretting wear.The fretting wear behavior of the steam generator tubes material Inconel690of nuclear power was investigated against1Cr13steel on the PLINT high temperature fretting wear testing machine under the following conditions, the temperature of20～25℃(air)、300℃(air) and300℃(N2), the normal load of20N,50N and100N, the displacement amplitudes from60μm to200μm. Fretting wear behaviors were analyzed in combination with microscopic examinations through scanning microscope, Step instrument (AMBIOS XP-2) and X-ray electron spectroscopy. The following conclusions were obtained:(1) The fretting curves of Inconel690steam generator tube materials showed the parallelogram under the set of the normal load and displacement amplitude. The fretting was located in the slip regime.(2) The friction coefficient gradually increased with the increase of displacement amplitude under the same load at the room temperature and high temperature. However, the friction coefficient decreased in the high-temperature nitrogen, adhesion was inhibited because of displacement increased, worn surface generate a layer of smooth and dense surface film which was lubrication(3) When load and displacement was fixed, the oxidation effect of high temperature had a positive role to promote the formation of the "third body" oxidation of wear debris layer and a large of wear debris congregated at the contact zone and played a protective role. The damage of wear was relative slightly. However, oxidation of wear debris was inhibited in the high-temperature nitrogen. Most of wear scar was bare. The surface of materials contacted directly. The damage of wear was more seriously.(4) The fretting wear mechanisms of Inconel690exhibited mainly abrasive wear, friction oxidation, and delamination mechanism at high temperatures. Friction oxidation and delamination were the main fretting wear mechanisms of Inconel690at the high temperature(T=300℃).Fretting wear mechanisms of Inconel690was mainly abrasive wear and delamination at the high-temperature nitrogen(T=300℃) atmosphere.