Effect of rolling process on comprehensive properties of corrosion resistant steel for bottom plate of cargo oil tanks

A new kind of corrosion resistant steel for cargo oil tanks (COT) was developed. The influences of final rolling temperature, cooling rate, and final cooling temperature on microstructure were investigated. The proper rolling process parameters were obtained through multi-pass thermal simulation test. The final rolling temperature is about 820 °C, the final cooling temperature is about 600 °C, and the cooling rate should be controlled between 10 °C/s and 20 °C/s. Based on the above analysis of the results, three groups of rolling samples by thermo mechanical control process are prepared. The tensile strength, yield strength, and toughness of the corrosion resistant steel are measured, which meet the requirements of DH36 steel, it can instruct the actual rolling production. The corrosion behaviour is also researched by weight loss and electrochemical impedance spectroscopic method, and it is found that the steel has good corrosion resistance performance, the best one is No.3 steel, the corrosion rate of which is about 1/4 of the accepted criterion.