Effect of Cooling Method of Heat-Treatment on Corrosion Resistance of 316-Q345 Composite Steel Bars

The effects of cooling methods of heat-treatment on the corrosion resistance of 316-Q345 composite steel bars were studied by means of microstructure observation, full immersion corrosion test and electrochemical testing. The results showed that the increase of cooling rate made the passivation film of 316 stainless steel coating more compact, both the passivation ability and the pitting resistance higher. The electrode potentials of the bonding interfaces were between those of the carbon steel and stainless steel. The decrease of cooling rate was beneficial to improve the corrosion resistance of the bonding interfaces and the metallurgical bonding between the coatings and the core material, but also led to the increase of the dilution degree of alloying elements in the coating, thus reducing the corrosion resistance of the coating.