Figure 8

Model curves calculated for different times of exposure, Monkman–Grant and time to rupture vs. nominal stress. Model curves calculated for different times of exposure (a,b); for each curve, the strengthening effect of the particles was assumed to be equivalent to that calculated for the reported time of exposure. The VLE data roughly align on the curve corresponding to the relevant time of exposure, which is correct, because the two values of the minimum creep rate for any VLE were obtained for times of exposure that had a minimal difference. (c) Monkman–Grant plot of the time to rupture as a function of minimum strain rate. The straight line in the figure was purposedly selected to provide a conservative estimate of the time to rupture (experimental values are in some cases 1.5–2 times larger than that calculated from the curve). For comparison purposes, the data for P91 from Ref.¹³ are also reported; (d) plot of time to rupture (h) vs nominal applied stress for the steel investigated in the present study. For comparison purposes, the data for 17-4PH steel from Ref.¹⁰ and for P91 from Ref.¹² are also reported. Dotted curves indicate extrapolations to be carefully considered.