Creep Resistance and Microstructure Evolution in HR3C-P92 Heterogeneous Welds

The paper deals with results of long-term stress rupture tests on „cross-weld“ specimens made of HR3C–P92 heterogeneous welds. Stress rupture tests were carried out in air at temperatures of 625 and 650 °C up to ca 20 000 h to rupture. Creep rupture strength values of HR3C–P92 welds for 104 h at both 625 and 650 °C were calculated. The preferential location of failure was the intercritical part of the heat affected zone in P92 steel. Local changes of hardness during creep exposure were evaluated by hardness profiles across the welds. Metallographic studies were performed in individual parts of heterogeneous welds. A special attention was paid to precipitation reactions in both base materials and heat affected zones.