Brazilian high temperature processed steels for pipelines

The present work continues part of an extensive program developed at PUC-Rio initiated in 2000 in collaboration with industry and other Brazilian research institutes, to facilitate the application of API 5L X80 line pipe in Brazilian construction projects. The production of API class steels using the traditional controlled rolling route, rather than accelerated cooling, as used in many other countries, necessitates a careful adjustment of steel composition combined with the optimisation of the rolling schedule for the deformation and phase transformation characteristics of these modified alloys. In the first part of this study, the evaluation of two Nb-Cr and NbCrMo steels systems was undertaken at two stages in the production route, this involved sampling the material as plate and as the final tubular product. Mechanical and microstructural characterization of the plate and tube, including the longitudinal (SAW) and circumferential SMAW weld were undertaken, as well as laboratory investigations of Environmentally Induced Cracking. The second part of this study evaluated the effect of the induction bending process on the microstructure and mechanical properties of the pipe obtained from a NbCrMoV steel system. (AU)