Surface Grain Boundary Characteristics and Electrochemical Behavior of Hot Rolled High Ni High Strength Steel

The surface grain boundary distribution characteristics and microtopography of hot rolled and heat treated 10CrNi5Mo high strength steel were tested by EBSD technology and AFM. The corrosion behavior of 10CrNi5Mo high strength steel was investigated by full immersion tests and electrochemical impedance spectroscopy(EIS) in simulated seawater environment. The results show that there is higher proportion of low angle grain boundaries on the surface of hot rolled 10CrNi5Mo high strength steel than that of the heat treated specimen. The corrosion of the heat treated specimen is more uniform and the roughness is less than that of the hot rolled specimen after nital corrosion. In the full immersion tests in simulated seawater environment, the hot rolled 10CrNi5Mo high strength steel presents a better corrosion resistance. The impedance increased in the mid- stage of immersion tests. The integration of corrosion products on the surface and matrix metal is closer so that the corrosion products can prevent the electrochemical reaction between the matrix metal and solution.