Fretting Wear Behavior Of Nc30Fe Alloy In Distilled Water And Hydrazine Solution

Fretting damage between the nuclear steam generator tubes and support plates has become one of the main reasons for breakage failure of steam generator tubes and energy loss. Therefore the study of fretting wear behavior of NC30Fe alloy in distilled water and hydrazine solution has practical significance for analyzing and solving the fretting damage of heat transfer tubes and improving the level of nuclear power equipment security by using the fretting wear theory.PLINT high temperature fretting wear test rig was used to investigate the fretting damage characteristic and mechanism of NC30Fe alloy in ambient, distilled water and hydrazine solution against1Cr13steel under the following conditions:the normal load (Fn) of20N,50N and100N respectively, the displacement amplitude (D) of100μm,150μm and200μm respectively at constant frequency (f) of2Hz, number of cycles (N) of2×104. The setting temperature were room temperature (20～25℃),50℃,80℃. The aqueous medium was distilled water and hydrazine solution respectively. Friction coefficient, worn surface, cross-section of wear scar and debris were analyzed by scanning electron microscopy (SEM), X-ray electron spectrometer, energy dispersive X-ray detector (EDX), and NanoMap500DLS dual-mode profilermeter after fretting wear tests. The following conclusions were obtained:(1) All the fretting logs under setting tests conditions were parallelogram which demonstrated that fretting logs were running in the slip regime and fretting wear was significant.(2) The friction coefficient and wear capacity in distilled water and hydrazine solution increased and the fretting damage became serious with temperature increased.(3) The friction coefficient in distilled water or hydrazine solution was decreased obviously compared with ambient, but it in distilled water was lowest. In comparison to ambient, the wear was lightened in distilled water or hydrazine solution significantly, but it was more serious in hydrazine solution than that in distilled water. (4) The abrasive wear, friction oxidation and delamination were the main wear mechanism of NC30Fe in ambient. However, in distilled water or hydrazine solution the abrasive wear and delamination were the main wear mechanisms of NC30Fe.(5) In ambient the main oxides of debris were Ni2O3, NiO, Cr2O3and Fe2O3at room temperature. In distilled water the main oxides of debris were Cr2O3, Cr(OH)3and FeOOH at room temperature, the main oxides of debris were Ni(OH)2,Cr2O3,Cr(OH)3and FeOOH at50℃, and the main oxides of debris were Ni(OH)2, NiO, Cr2O3, Cr(OH)3and Fe2O3at80℃.In hydrazine solution the main oxides of debris were Cr2O3, Cr(OH)3and FeOOH at room temperature, the main oxides of debris were Ni(OH)2, NiO, Cr2O3, Cr(OH)3and FeOOH at50℃, the main oxides of debris were Ni2O3, Cr2O3, Cr(OH)3, FeO and Fe2O3/Fe3O4at80℃.