Study On Tangential Fretting Wear Behavior Of Inconel690Alloy Tube Materials In Deionized Water Under Normal Pressure

Steam generator (SG) is one of the major equipments used in the nuclear power plant. The fretting damage (i.e. fretting wear and fatigue) can occur between heat exchanger tubes and anti-vibration bar or support plate as a result of flow induced vibration and thermal cycling effect. This effect is induced by the HTHP (high temperature and high pressure) water vapor at the SG secondary side. Finally, the heat exchanger tubes become thinning and then the U-tube lifetime is reduced significantly. Therefore, this thesis is aimed to study the tangential fretting characteristics and damage mechanism of Inconel690in the water media. This study not only provides a guiding significance for the service behavior of the key materials of the nuclear steam generator, but also enriches and develops the fretting tribology theories.In this paper, Domestic and imported Incone1690alloy heat exchanger tube against405stainless steel flat were chosen to study. The fretting tests were carried out on two tribotesters including PLINT TE77tangential fretting wear and MFF-3000electromagnetic vibration fretting fatigue and wear tester. The experiments on PLINT TE77were aimed to study the fretting wear behavior under the conditions of various temperature (room temperature,60℃and90℃), low frequency large displacement amplitude and deionized water. The other one studied the conditions of room temperature, deionized water, high frequency and small amplitude. Optical microscope (OM), scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDX) and3D optical profile-meter were used to study the worn surface of materials. The conclusions are listed as follows:1. The tangential fretting running behaviors and fretting damage mechanisms of Incone1690alloy tubes in the low frequency and large displacement amplitude(i) All friction-displacement (Ft-D) curves in this research are parallelogram, indicating that the fretting is running in the gross slip regime.(ii) The fretting damage of imported Incone1690alloy heat exchanger tube is more serious than domestic Incone1690alloy heat exchanger tube under different temperature and deionized water. The fretting wear mechanisms of the two materials exhibited mainly abrasive wear and delamination. In the slip regime (SR), severe damage appeared in high temperature of deionized water when the normal load and displacement amplitude is not changed. It is because the oxidation increased and the wear rate increased. Severe damage was appeared and wear rate raised with increasing displacement amplitude under the same normal load and the temperature of deionized water. 2. The tangential fretting running behaviors and fretting damage mechanisms of Incone1690alloy tubes in the high frequency and small displacement amplitude(i) In RT deionized water, two kinds of fretting loops are observed, i.e. ellipse and parallelogram curve. The mixed fretting regime failed to be observed in this study. The wear was increased as the increase of displacement of amplitude. At the same time, the fretting transformed from partial slip regime (PSR) to gross slip regime (GSR).(ii) In the partial slip regime (PSR) and the slip regime (SR), the fretting wear mechanisms of domestic Incone1690alloy in RT deionized water was combined with abrasive wear and delamination.