Effects of plastic straining on the corrosion resistance of TRIP-aided lean duplex stainless steels

In the present paper, the effects of plastic deformation on the corrosion resistance of strip cast TRIP (transformation-induced plasticity)-aided stainless steel (19Cr-DSS) and conventional lean duplex stainless steel (LDX2101) were studied by observations of deformed microstructure and electrochemical experiments. The electrochemical results indicate that the corrosion susceptibility of experimental steels in 3.5% NaCl solution is increased with increasing deformation amounts. The Mott-Schottky analysis revealed that the passive films formed on both 19Cr-DSS and LDX2101 exhibit the n-type and p-type semiconducting behaviors regardless of strains. With the increase in true strain, the acceptor and donor densities are both continuously increased. The total density of acceptor and donor in 19Cr-DSS is increased more rapidly with increasing strain than that of LDX2101, indicating that the corrosion resistance of 19Cr-DSS is more sensitive to plastic deformation compared to that of LDX2101. For the TRIP-aided 19Cr-DSS, the deterioration of corrosion resistance after plastic deformation may have been caused by the decrease in low-I pound CSL boundaries especially the twin (I 3) pound boundaries, the increase in dislocations, and the formation of strain-induced martensite during plastic deformation.