The development of high performance low carbon bainitic steel

The yield strength 550MPa-960MPa grade low carbon bainitic steels have been developing in China. By newly developed relaxation- precipitation-phase transformation control (RPC) process, the packet size of bainite can be refined to 3 microns in width and 6 microns in length. As the cost consideration, high Nb content (0.1%) concept (Mn-Nb-B) has been applied to develop 550MPa-960MPa grade plate steel too. The optimized thermo-mechanical control process (TMCP) and tempering process have been revealed, the role of solute and precipitate Nb has be discussed. These years, more than 100,000 tons/annul of low carbon bainitic plate steel have been produced by advanced gain refinement technology and lower cost microalloying approach. (AU)