| The long term high temperature creep/stress-rupture behavior of 2 1/4Cr {dollar}-{dollar} 1Mo low alloy steel is known to depend on prior thermal exposure. Understanding and predicting this behavior is important in service life assessment of pressurized piping, vessels, and other load bearing components. The effects of field hot fabrication and heat treatment on the service life are also important. A model has recently been developed to predict the effect of service exposures. Its applicability to the other type of thermal exposure is not known.; Typical commercial ASME SA335 P22 piping material was utilized. Heat treatments ranged from normal service exposure at 1005{dollar}spcirc{dollar}F, to exposures typical of field hot bending processes, and extended exposures above and below the Ac{dollar}sb1{dollar} temperature. Both weld containing and base metal samples were included. Stress-rupture performance was quantified and correlated with such life prediction parameters as hardness, and carbide morphology. Comparison with the model was made, and the applicability of the laboratory data to field installed piping was evaluated by field hardness testing and metallographic replication.; It was found that the normal service exposed material obeyed the model closely, while the additionally heat treated materials deviated in the nonconservative direction. All additional heat treatments were found to be deleterious, and welded samples had poorer properties than their base metal counterparts. Field characterization methods were found to be limited by anomalous surface conditions. |
