Cold Bending of Advanced Ferritic Steels: ASTM Grades T23, T91, T92

The metallurgical background of advanced ferritic steels must be considered during every stage of fabrication, including during forming operations, such as cold bending, because they can negatively affect the high temperature properties of the material if they are not performed properly. In this work, the results of a broad cold bending program carried out on ASTM Grades T23, T91 and T92 tubes are presented: the microstructure and the mechanical properties at extrados and intrados positions were investigated and compared with properties of unbent materials. Creep properties were assessed by means of specimens directly machined from extrados and intrados of real bends. This paper aims to integrate the International Codes for cold bending with recommendations for proper post bending heat treatments, in order to obtain a final component with the desired microstructure and mechanical properties, including optimum creep resistance.