Assessment of intergranular corrosion in AISI Type 316L stainless steel weldments

Abstract

A ST M G108 ( the electrochemicalpotentiokinetic reactivation ( EPR) test) . T he possibility of using eddy current testing ( ECT) to detect sensitisation and IGC was also assessed. T he

Study of the sensitisation process of a duplex stainless steel (UNS 1.4462) by means of confocal microscopy and localised electrochemical techniques

“…Therefore, the formation of the sigma phase causes a decrease in the corrosion resistance of the alloy. These results are in agreement with several authors who propose that the sensitisation process increases the susceptibility of stainless steels to the formation of pits [2,[36][37][38][39][40][41]. A clear increment in the passive current density is not observed, probably consequence of the use of a diluted solution.…”

Corrosion Characteristics of Laser-Engineered Net Shaping Additively-Manufactured 316L Stainless Steel

“…40,[43][44][45][46] Therefore, since the PBF-L-produced 316L SS was not heat treated, a direct comparison between the two materials is difficult, especially since as-deposited AM and welded materials are known to include residual stresses that can deteriorate corrosion resistance. 16,[23][24][25] SS produced by PM or subject to welding methods is also recognized for having an increased degree of sensitization, due to increased porosity and localized heating, compared with wrought material. 16,[23][24][25]49,50 In PM SS, the degree of sensitization is increased due to the porosity, which behaves similarly to pre-existing crevices, resulting in an increased corrosion rate.…”

“…[20][21][22] Welding and AM processes can also cause local heating and subsequent cooling, which create residual stresses that can impact the corrosion resistance, fatigue wear, and induce stress corrosion cracking. 16,[23][24][25] In certain corrosive environments, such as those used in electrochemical potentiokinetic reactivation (EPR) tests, the material can become sensitized when the chromium content is less than 12-13% in the chromium-depleted regions. Austenitic SSs, such as 316 (18Cr-12Ni-2Mo) and 304 (18Cr-8Ni), are susceptible to corrosion via intergranular corrosion (IGC) and intergranular stress corrosion cracking (IGSCC) due to sensitization.…”

Role of Modern Localised Electrochemical Techniques to Evaluate the Corrosion on Heterogeneous Surfaces

“…When austenitic stainless steels are incorrectly heat treated, in the temperature range between 500 and 900 °C, chromium and carbon combine at the grain boundaries to form chromium carbides (typically Cr 23 C 6 ), whilst simultaneously as these carbides form, chromium depletion occurs at the adjacent zones. This process is called sensitisation and leads to a decrease in the corrosion resistance of stainless steels, notably resistance to intergranular corrosion, being due to the depleted regions becoming anodic in the presence of an electrolyte [24][25][26][27][28][29][30]. These heat treatments generate heterogeneous surfaces on the stainless steels.…”