Production and properties on pipeline steels with non-polygonal ferrite microstructure

Flows, and subsquently pressures, in gas pipelines are beinp steadily increased in an effort to reduce costs. This may indicate a demand for Grade X80 pipe in the not too distant future. In this regard, pipeline steels with non-poligonal ferrite microstructure will certainly come to assume greater importance, because their mechanical properties are intrinsically better than those with ferrite-pearlite microstructures. The manufacture of Grade X80 pipe requires a careful examination of the contribution made by control rolling and conventional heat treatment and by on-line treatment such as direct quenching and accelerated cooling (which have yet to be developed for full-scale works application). (AU)