HIGH STRENGTH BAINITIC STEEL FOR OCTG APPLICATIONS.

摘要

A high strength bainitic steel and a process for producing seamless pipes for OCTG applications are described. In particular, the advantages ensuing to the steel of the invention are the improvement in strength-toughness over tempered martensitic steels, and a simplified thermal treatment. Quenching is not necessary and by avoiding the quenching treatment the microstructure results far more homogeneous, which allows thick walled tubes to be produced. For the same steel composition, in comparison to conventional tempered martensitic structures, a better combination of strength and toughness can be achieved, in particular by tempering as rolled carbide-free bainitic structures.