Ageing effects on a' precipitation and resistance to corrosion of a novel Cr-Mo stainless steel with high Mo content

摘要

The consequences of ageing at 400 and 475 °C on a~1 precipitation and corrosion resistance of a novel Cr_Mo ferritic SS with high Mo content were investigated. Combination of X-ray diffraction and M_ssbauer spec_troscopy 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 a phase and is thus asso_ciated with a Cr-rich a' 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 para_magnetic phase leads to discontinuities in the oxide layer thus reducing corrosion protection and exposing the steel to the action of the corrosive solution.