MICROSTRUCTURE BEHAVIOR OF STEEL 15 CRMOV 5 10 UNDER CREEP CONDITIONS

Investigations of the influence of heat treatment (cooling rate from a ustenitizing temperature, tempering conditions) on the mechanical prop erties at room temperature as well as the structural parameters, which influence the creep resistant properties - bainite content, type, qua ntity, size and distribution of carbides, alloying content of the matr ix - were made on the heat resistant pipe steel 15 CrMoV 5 10. The str uctures, produced by optimized heat treatment conditions, are characte rized by a high bainite content as well as finely dispersed VCN- and M o2C-precipitates and small grain boundary carbides. During the creep p rocess more Mo2C-carbides precipitate above all at the dislocations in hibiting their motion. This process is accelerated by creep deformatio n and essentially contributes to the long-term creep resistance of the steel 15 CrMoV 5 10.