利用新近研制的双相流冲刷腐蚀激光多普勒实验装置,通过失重测试、表面形貌观察、局部流速流态测试和典型部位的电化学测试，研究了突扩管条件下不锈钢AISI316L在单相及含砂人工海水介质中的冲刷腐蚀机理。结果表明：冲刷腐蚀峰值发生在距突扩位置约3.0D的部位(D为粗管直径),与切向流速扰动度的峰值位置相同.在3.0D和5.5D的部位,冲刷作用是主要的,而在回流区(1.5D),则为氧扩散控制.不同部位的冲刷腐蚀形貌有明显差异,并与局部流速流态是相互对应的.冲刷电流随流速的提高而增大以及致钝峰的出现.
The erosion-corrosion mechanism of AISI316L in artificial sea water with or without different silica sand under sudden pipe expansion condition was investigated through weight loss test, surface morphology observaton,local flow regume measurements (LDA)and electrochemical measurements at specific position.The results showed that the maximum of erosion-corrosion was located at about 3.0D (large pipe diameter) downstream the sudden pipe expansion whic was the same as the maximum of turbulent fluctuations of tangential velocity of 1.5mm away from the pipe wall.The erosion-corrosion of 3.0D and 5.5D downstream the sudden pipe expansion dominated, in contrast, that of 1.5D (recirculation zone )was oxygen diffusion controlled.The erosion-corrosion morphologies at different positions were significanly different. which was just responding the local flow regime .The effects of erosion on corrosion were not only due to the enhanced mass transfer of the oxygen, but also due to the weakness and/or breakdown of passive film.
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