Effect of Temperature and Grain Size on the Corrosion Behavior of 316L Stainless Steel in Seawater

Abstract

This study involves effect of aluminum coating by using different techniques (Aluminizing, Flame spraying, and Hot dipping) on corrosion behavior of stainless steel 316L in seawater. Cathodic and anodic regions are studied by using potentiostat to measure the corrosion parameters through Tafel method which include open circuit potential (E ocp), corrosion potential (E corr), and corrosion current density (i corr) in addition to calculation of coating corrosion rates (R). The results indicate that the corrosion rate for coated specimens by aluminizing and flame spraying techniques were less than the values before coating but coating with hot dipping technique gives higher rate than the non coated samples, where the results take the following sequence: Corrosion coating sample < coating sample < coating sample Rate (μm/y) by using pack using flame spray using hot dipping cementation aluminizing The potentials with time were interpreted in order to study the evolution of the film chemistry as it came to equilibrium with solution where the results observed that the aluminum coating by aluminizing reaches to the steady-state faster than other samples. Also the galvanic current density with time were discussed where the results indicates, in general, the transients for specimens show an initial sharp decrease in galvanic current exhibited by all coated specimens followed by a more steady, but erratic decrease in the galvanic current.

Effects of Aging at 450°C on the Pitting Corrosion Resistance and Toughness of AISI 317L Steel Welded by GTAW and FSW

“…The lower corrosion resistance of FSW after aging for 200h and 300h can also be explained by its fine grained structure. Some studies 18,19 suggest that refining of the austenitic grain decreases the pitting corrosion resistance due to the increased diffusion efficiency of Cr and Mo, which favors the intermetallic precipitation during aging.…”

Study on pitting behavior of HDR duplex stainless steel at different film-forming potentials

“…When the porosity is large, the outer layer resistance R 1 approximately corresponds to the resistance of the electrolyte in the pores [24], causing the resistance R 1 to decrease with the increase of the potential. On the other hand, as the film-forming potential increases, the generation speed of the outer film at the metal/solution interface increases, the concentration of oxygen vacancies (N-type semiconductor main acceptor) increases, the impurity ions increase [25], the stability of the passivation film weakens, and it will also promote the adsorption of Cl − and other corrosive ions, thereby promoting the rupture of the passivation film and leading to pitting [26,27]. As the potential increases, the polarization effect strengthens, causing the dissolution rate of the inner film to accelerate.…”

Effect of Passivation on Pitting Corrosion of 316L Stainless Steel in Concentrated Seawater

“…Chloride ion in seawater can be preferentially adsorbed in the passive film (especially the defects), crowding out of the oxygen, and then combining with cation of the passive film into the soluble chloride. Afterwards, exposed substrate came into being new pit nucleus, and developed into pits at last [5]. In the one hour of open-circuit potential test, a passive film formed on the surface of matrix specimen gradually by nature, while the formed passive film of passivated specimen dissolved (Fig 1).…”