Electrochemical behavior of corrosion of a sinterized stainless steel with different boron additions
Keywords:
Boron, Corrosion, Liquid phase, powder metallurhy, sinteringAbstract
Powder metallurgy (PM) is an effective method tomanufacture high quality and accurate parts at alow cost. However, the use of these parts is limiteddue to their low sintered density, which reduces thecorrosion resistance. The objective of the presentwork was to determine the corrosion behavior of409Nb stainless steel specimens sintered and dopedwith different boron contents. The boron is addedto promote the formation of a liquid phase duringsintering at 1,150 oC, which consequently seducesthe amount of porosity and increases the density,resulting in an improved corrosion resistance. Forthis study the techniques of linear polarizationresistance (LPR) and electrochemical noise (EN) inboth potential and current were used. The LPR andEN techniques were used to know the corrosionbehavior of specimens with and without boronadditions in two solutions, namely 0.5M of H2SO4and 0.5M of NaCl. The results obtained allowed toestimate the corrosion rate and disclose the corrosionmechanism. It was concluded that the specimensdoped with boron are more susceptible to corrosionin both solutions due to the precipitation ofchromium rich compounds. The EN measurementsindicate attack by mixed corrosion in the H2SO4solution, whereas in the NaCl solution the samplessuffered localized corrosion.
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