ELECTROCHEMICAL NOISE MEASUREMENTS TO MONITOR FLOW CORROSION OF AISI 304L STAINLESS STEEL

摘要

Electrochemical noise measurements of AISI 304L stainless steel were made in a pipe test section of 28 mm inside diameter for a range of flow regimes from laminar to turbulent. Flow velocities through the test section were controlled at 0.04, 0.07, 0.11, 0.36, 1.8 and 2.7 ms-1, equivalent to Reynolds numbers of 1000, 2000, 3000, 10000, 50000 and 75000, respectively. Standard hydrodynamic parameters were employed to characterise the interrelationship between the mass transfer rate of oxygen and momentum transfer through turbulence to the metal/solution interface. Metastable pitting was evident under all flow regimes. Fluid flow, whether laminar or turbulent, appeared to have little overall effect on the nucleation rates of metastable pitting events. Conversely, stable pit growth was most evident at Reynolds numbers immediately before the transition to turbulent flow and close to the critical velocity at Re numbers of approximately 2000 and 50000 respectively.