Creep Fatigue Crack Growth Testing in P91 Steel
In response to the availability of on line renewable energy and the transient fluctuation in energy demands, it is required that the power output conventional power plant is altered accordingly i.e. they are operated in a flexible manner. Many conventional power plants have been in operation for many years and therefore significant creep strain/damage or even defects may exist in their high temperature components. Flexible operation may in addition generate significant fatigue loading in these components. Many high temperature components, such as pipes, in conventional plant have been manufactured from P91 steel. This work aims to examine the interactive effects of creep and fatigue on a defected P91 component. Interactive creep fatigue crack growth tests have been performed on compact tension specimens made out of P91 steel at 600 degC and 625 degC. The crack growth rates have been correlated with the linear elastic fracture mechanics parameter K and the creep fracture mechanics parameter C* Metallography and fractography has also been performed to examine the predominant modes of fracture