Microstructural aspects of superior creep resistance of a 10%Cr martensitic steel

Published on Dec 15, 2016in Materials Science and Engineering A-structural Materials Properties Microstructure and Processing4.652
· DOI :10.1016/J.MSEA.2016.09.096
R. Mishnev10
Estimated H-index: 10
(Belgorod State University),
Nadezhda Dudova13
Estimated H-index: 13
(Belgorod State University)
+ 1 AuthorsRustam Kaibyshev58
Estimated H-index: 58
(Belgorod State University)
Sources
Abstract
Abstract The microstructural evolution and the dispersion of secondary phases were studied in a low-nitrogen 10%Cr martensitic steel with 3% Co and 0.008% B additives at 650 °C under an applied stress of 140 MPa. It was demonstrated that the superior creep strength of this steel can be attributed to the high resistance of M 23 C 6 -type carbides and Nb-rich MX carbonitrides against coarsening, resulting in a stable of the tempered martensite lath structure (TMLS) under short-term creep conditions. The TMLS remains slightly changed under creep: lath coarsening occurs with a two-fold decrease in the lattice dislocation density. M 23 C 6 -type carbides were found to give the main contribution in hindering the transformation of interlath boundaries to subgrain boundaries, impeding the migration of low-angle boundaries by exerting a large pinning pressure. A high Zener drag pressure is maintained up to rupture. The precipitation of a Laves phase under creep conditions results in a minor contribution to the overall pinning pressure. V-rich MX carbonitrides tend to dissolve with increasing time. No formation of a Z-phase was detected. M 23 C 6 carbides retain their orientation relationship with ferritic matrix up to rupture. No significant strain-induced coarsening of M 23 C 6 carbides, Laves phase, or MX carbonitrides was observed.
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