4. Conclusions
In this work the effect of PWHT’s of varying duration on the hardness of a welded joint of a P91 steel were studied. The analysis of cross sections of the welds suggests the following conclusions: x A narrow heat-affected zone (HAZ) 4 mm wide was detected, composed by a thin (a0.2 mm) coarse-grained layer with high hardness, a fine-grained region exhibiting grains up to 4 μm in size, and a soft intercritical region with low hardness, located 3 to 4 mm away from the fusion line. x The results of hardness measurements suggest that a PWHT of 2h at 760 ºC is enough to reestablish the strength of the P91 steel after the welding process.
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