Investigation on mechanism of type IV cracking in P92 steel at 650 °C

Welded joints of P92 steel subjected to creep testing at 650 °C and 70 MPa were investigated. Type IV cracking was observed in the fine-grained heat-affected zone (FGHAZ) of the welded joints by optical microscopy. It was found that with varying creep times, the number of creep voids increased at an accelerating rate and the maximum number of voids was formed in the FGHAZ. Scanning electron microscopy observations revealed that precipitates were...