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I. Holzer, E. Kozeschnik, H. Cerjak:
"A numerical approach to predict the long-term creep behaviour and precipitate back-stress evolution of 9-12% Cr steels";
Talk: Liege Conference: Materials for Advanced Power Engineering 2010, Liege, Belgium; 09-27-2010 - 09-29-2010; in: "Materials for Advanced Power Engineering", (2010), 1077 - 1087.

The mechanical properties of modern 9-12% Cr steels are significantly influenced by the presence and stability
of different precipitate populations. These secondary phases grow, coarsen and, sometimes, dissolve again
during heat treatment and service, which leads to a remarkable change in the obstacle effect of these precipitates
on dislocation movement. In the present work, the experimentally observed creep rupture strength of a modified
9-12% Cr steel developed in the European COST Group is compared to the calculated maximum obstacle effect
(Orowan threshold stress) caused by the precipitates present in the investigated alloy for different heat treatment
conditions. It is shown that the differences in creep rupture strength caused by different heat treatments disappear
after long time service. This observation is discussed on the basis of the calculated evolution of the precipitate
microstructure. The concept of boosting long-term creep rupture strength by maximizing the initial creep
strength with optimum quality heat treatment parameters for precipitation strengthening is critically assessed.