Enhancement of corrosion resistance of CrMoV low alloy steels using cryogenic treatment

Abstract

The current investigation explores the effect of cryogenic treatment on the microstructural and corrosion behavior of CrMoV low-alloy steels. The casted samples in the required dimensions were treated by annealing followed by deep cryogenic treatment (DCT). Initially, the microstructural modification brought by combined treatments was studied using an optical microscope (OM), scanning electron microscope (SEM), and x-ray diffraction (XRD) technique. After DCT, a refined and uniform grain structure was identified. The DCT resulted in the development of a fine-grained structure and reduced the mean grain size of the alloy, and this refinement of the grain structure is due to the reduction of lattice defects during the cooling process. The corrosion behavior was studied using the weight loss and Tafel polarization tests. The corrosion findings indicated a significant enhancement in the corrosion resistance of the specimens after DCT. The DCT specimens exhibited higher corrosion potentials compared to the base material. The DCT can promote the development of a more protective passive layer on the sample’s surface. This passive layer serves as an obstacle, preventing the diffusion of corrosive products and increasing corrosion resistance. Finally, it suggests that DCT positively impacts the CrMoV steels’ resistance to corrosion.