1993 Volume 79 Issue 8 Pages 988-995
The effect of Cr, Mo, W, Mn and Ni contents on the creep properties of a 2.25Cr-Mo-V based bainitic steel was investigated and microstructural factors which affect the creep rupture strength were discussed. The creep rupture strength is decreased by increasing Cr, Mn and Ni contents although it is slightly increased with the addition of W. The effect of Mo is very small. Addition of Ni in excess of 1.8% decreases the creep rupture strength remarkably.
Preferable precipitation of Cr23C6 and Cr7C3 due to the increase of Cr content suppresses the precipitation of V4C3, and decreases the creep rupture strength. Ni and/or Mn addition decreases the creep rupture strength because the stacking fault energy which makes cross slip easier is increased. No further improvement of creep rupture strength due to solid solution strengthening is expected by the addition of Mo in excess of 0.8%. W contributes to the increase in creep rupture strength through solid solution strengthening effect. In addition, it is concluded that the creep rupture strength of the 2.25Cr-Mo-V steels equals or exceeds that of the conventional 1Cr-Mo-V steels.
