Ergebnisse von Zeitstandversuchen mit glatten und gekerbten Proben aus den Stählen 20 CrMoV 13 5 und X20CrMoWV 121

Results of Creep Tests With Smooth and Notched Specimens of the Steels 20 CrMoV 13 5 and X20 CrMoWV 121 Two hydrogen resistant steels, viz. 20 CrMoV 13 5 W.-Nr. 1.7779) and X20 CrMoWV 12 1 (W.-Nr. 1.4935) used for bolts and nuts as well as for pressurized components were tested with respect to their creep resistance. Using smooth and notched specimens creep data for 450°C 500°C and 550°C were established. Steel 20CrMoV 13 5 was investigated in two quenched and tempered states (225…250 HB, 285…310 HB. The tempering treatments of X20 CrMoWV 12 1 (W.-Nr. 1.4935) lead to hardness levels of 215…226 HB resp. 275… 310 HB. Creep tests at 450°C and 500°C resp. at 500°C and 550°C were undertaken with smooth and notched specimens of 20 CrMoV 13 5-resp. X20 CrMoWV 12 1 -steels. At each temperature two resp. three different hardness levels were investigated which were produced by changing the quenching and tempering procedure. The results prove the X20 CrMoWV 12 1-steel to show high ductility in all three Q + T conditions even after long creep tests. This holds true for the 20 CrMoV 13 5-steel in the soft condition and at a test temperature of 450°C only. The creep strength of both steels is about proportional to the ultimate strength of both steels is about proportional to the ultimate strength at room temperature. With regard to the allowable stresses it could be shown that in each case the creep strength for 100.000 hours divided by a safety factor of 1.5 is smaller than the 1% creep limit for the same time.