The influence of Cr on the microstructure and electrochemical behavior of high strength low-alloy steel

The influence of Cr addition (0.13 wt%, 0.65 wt% and 1.07 wt%) on the microstructure, phase structure and electrochemical behavior of high strength low-alloy (HSLA) steel was investigated. The surface morphologies of HSLA steels were examined by Optical microscopy (OM) and Scanning electron microscopy (SEM). The phase structure was analyzed by x-ray diffraction (XRD). Electrochemical tests were used to study the corrosion behavior of high strength steel in 3.5 wt% NaCl solution. The results showed that the appropriate addition of Cr (1.07 wt%) alloying significantly refined grain, improved the electrochemical property and microstructure. The microstructure of all samples were the typical bcc (alpha) phase and the peaks including (110), (200), (211) and (220) got stronger with the increase of Cr content. Meanwhile, the T3 steel with 1.07 wt% Cr showed the best electrochemical reaction inhibition and corrosion resistance because of the highest Rt. And the corrosion morphology was from serious intergranular corrosion and pitting corrosion to slight localized corrosion with the increase of Cr contents.