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.