Ageing effects on α′ precipitation and resistance to corrosion of a novel Cr–Mo stainless steel with high Mo content
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The consequences of ageing at 400 and 475 °C on α′ precipitation and corrosion resistance of a novel Cr–Mo ferritic SS with high Mo content were investigated. Combination of X-ray diffraction and Mössbauer spectroscopy results indicates the appearance of a small amount of a paramagnetic phase as a result of the ageing. This phase is iso-structural with the α phase and is thus associated with a Cr-rich α′ phase. The appearance of this phase is related to a decrease of the resistance to corrosion as studied by DL-EPR because the presence of this paramagnetic phase leads to discontinuities in the oxide layer thus reducing corrosion protection and exposing the steel to the action of the corrosive solution.
KeywordsStress Corrosion Crack Duplex Stainless Steel Distillation Tower Ferritic Stainless Steel Paramagnetic Phase
The authors are grateful to the Brazilian research agencies Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico (FUNCAP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); and Agência Nacional de Petróleo (ANP) for financial support, and to Prof. Pedro de Lima Neto for DL-EPR measurements.