Influence of Long Term Ageing on Fatigue Crack Growth Behavior of P91 Steel at Different Temperatures

inluence of loading cycle asymmetry and long-term thermal exposure on fatigue crack growth rate in martensitic P91 and P92 steels

“…On the other hand, for P91 steel effect of cycle asymmetry is more significant and is equal about 30 % at ΔK = 20 MPa.m 1/2 . Obtained results are in very good agreement with similar experimental work [7,8], at higher asymmetry crack grows a little bit faster especially in the case of P91 steel. This effect is determined by higher value of constant C in Paris law equation.…”

“…Similar results were obtained for both steel and for both cycle asymmetry and shows good microstructural stability at given condition if the exposure. On the contrary the crack growth rate for aged material (20 000 hours at 550 °C) was found to be higher than that on unaged in work [8] due to precipitation of Laces phase. Presence of this Laves phase in both steel investigated in this work was not confirmed after 5 000 hours in study [9] on the other hand specimens with 15 000 hours exposure will be able for experimental work in the next year.…”

“…As the operating condition is not only creep conditions and fatigue loading also occurs material behavior under Paris law should be taking into account in design procedure of similar components. Effect of temperature on fatigue crack growth in P92 at R = 0.1 has been studied in [7] whereas effect of long term aging (20 000 hours at 550 °C) on crack growth in P91 at different temperature has been investigated in [8].…”