CORROSION BEHAVIOR OF NEW Cr-Ni-Cu LOW ALLOY SEAWATER CORROSION RESISTANT STEEL

摘要

Two kinds of Cr-Ni-Cu low alloyed steels were designed, 0.1%C-0.7%Cr-1.2%Ni-0.7Cu and 0.1%C-0.7%Cr-0.3%Ni-0.5Cu. With the method of SEM, XRD and electrochemical analysis and testing technology, periodic immersion accelerated corrosion test was carried out to investigate the corrosion resistance of the designed steels in simulated marine environment. The steel with best corrosion resistance was selected, and then focused on the variation of its con-osion rate with time. The results indicated that the designed Cu-Cr-Ni low alloyed steels showed better corrosion resistance than 20MnSi, the ratio of their corrosion rates was 0.44. The conosion rate of designed steels decreased gradually to 3~4 g/(mm~22h) with the elongation of test period, while the conosion rate of 20MnSi kept downward trend, not reach stability, and the conosion rate gap between them became smaller. The Cr element banding enriched in the inner rust can withstand the diffusion of CI~-. Besides, the addition of M raised the self-conosion potential of the bare steels and promoted the transformation of y-FeOOH to a-FeOOH, and consequently, improved the stability of the rust and the conosion resistance of steels.