Creep crack growth behavior of P91 steel weldments

The steels operating at elevated temperatures are well known to be exposed to premature failure due to cracking caused by constant thermal stress, i. e. secondary creep process. Therefore, creep crack growth tests were carried out on compact tension specimens machined from P91 weld joint at 600°C to determine its behavior in realistic conditions. At the same time, numerical method for predicting the creep crack growth in compact tension specimens by a series of incremental steady-state finite element analysis were performed using Norton’s law to represent creep behavior. Verification of the finite element predictions were obtained for weld metal and heat affected zone by comparison with experimental results, indicating at the same time that creep crack growth rates are significantly higher for weld metal than for base metal.