The mechanical properties and corrosion behaviors of ultra-low carbon microalloying steel

The continuous cooling transformation (CCT) microstructure evolution in low carbon Mo–Nb–Cu–B microalloying steel (LCS) was investigated by thermo-simulation test. It was found that the full multi-phase of intermediate transformation products could be obtained at cooling rate greater than approximately 2 °C/s. In order to get bainitic microstructures, the thermo-mechanical control process (TMCP) was worked out according to CCT microstructure characteristics. After TMCP, 750 MPa grade steel twice over that of weathering steel 09CuPCrNi (WS) with ferrite and pearlite structures could be achieved. The corrosion behaviors of LCS and WS were also studied by wet-dry cycle corrosion test. The results showed that LCS had higher corrosion resistance than WS, attributed to suppression of the formation of pearlite.