Thermomechanical processing of copper bearing HSLA steels

Thermomechanical simulation has been done with different predetermined schedules for Cu bearing HSLA steels. Understanding on the phase transformation effected during thermomechanical processing of such steels is attempted on the basis of microstructural and mechanical property studies. CCT diagram of the same steel is also constructed in the thermomechanical simulator in order to best the microstructural constituents. The results are interpreted in terms of the present nomenclatures used for the decomposition of austenite formed at low transformation temperatures. It is observed that the microstructures are essentially lath martensitic with microalloy carbides formed within the laths. The presence of MA constituents in the microstructure is found to be related to the thermomechanical processing schedules. It is further notice that the thermomechanical processing of these steels influence its ageing behaviour quite significantly. It is found that a controlled precipitation of copper through suitable thermomechanical processing can dispense with the costly quenching and tempering operations, yet yielding favourable properties for offshore applications.