Fretting Wear Behavior Of Alloy-800 At High Temperature

Energy has been a strategic problem which limits sustaining economy development of our nation.However,nuclear energy is one of the main paths to solve the energy issue.A steam generator(SG) tube materials in nuclear power plants is one of the most important components.Fretting wear has become one of the primary reason to steam generator(SG) tube cracking.So investigation on Fretting wear and damage mechanisms of steam generator(SG) tube at high temperature are of great imporptance in prolonging steam generator(SG) tube' life and improving the reliability of steam generator(SG) tube.The fretting wear behavior of Alloy-800 steam generator tube materials has been investigatded on a Deltalab-Nene7 under normal load(80N),displacement amplitudes (2-80μm) and temperatures(25℃,300℃and 400℃).Fretting wear behaviours were analyzed in combination with microscopic exminations through optical microscope, laser confocal scanning microscopy(LCSM) and scanning microscope(SEM).The following conclusions were obtained.1.Fretting running rule of Alloy-800 steam generator tube materials obey the fretting maps theory under three temperatures.Fretting running regimes of Alloy-800 steam generator tube materials are made up of partial slip regime,mixed regime and slip regime.2.The fretting regime of Alloy-800 is transformed from partial slip regime into mixed fretting regime and gross slip regime by its fretting behavior with increasing displacement amplitude at the same normal load and temperature conditions,fretting regime almost not change with the increase of temperature.3.The friction coefficients decrease with the increase of temperature in mixed fretting regime and gross slip regime;with the temperature changes from25℃to400℃,friction oxidation have a accelerated oxidation function,oxidation body had been eased film due to wear debris in the process of fretting wear;hower, for partial slip regime the friction coefficients hardly change with the change of temperature.4.Abrasive wear and oxidation are main fretting wear mechanisms of Alloy-800 at the temperature(T=25℃).The fretting wear mechanisms of Alloy-800 exhibited mainly friction oxidation,abrasive wear and delamination mechanism at high temperatures(T=300℃and T=400℃).