Microstructure and Creep Behavior Property of Dissimilar Joints Between Incoloy 800HT and P91 Steel

Abstract

Dissimilar joints are commonly encountered in the fabrication of high-temperature power plant components. In this current work, dissimilar joints between P91 and Incoloy 800HT have been produced using two different types of filler materials like ER505 and ERNiCr-3 with the GTAW welding process. Microstructure characterization of the weld metal reveals the presence of columnar dendritic structures. The microhardness value is higher in ER 505 filler-based weldment due to the formation of δ ferrite, M23C6 and MX precipitates. Impression creep test of dissimilar weldments has been conducted with the help of flat bottom cylindrical punch. The impression creep test has been carried out at the temperature of 873.15 K and 923.15 K with a constant load of 135 Mpa with 7200 s of holding time by using a vacuum of the order of 1 × 10−6 mbar in the heating chamber. The impression creep test result has revealed that the depth of penetration of weld with ER505 filler metal has a higher value compared to other weldments. The creep strength of the specimen is compared by the calculated activation energy of each specimen. The creep strength of the weld with ER505 filler metal (Exp No 4) is higher than that of all the other weld’s specimens. Hence, the dissimilar weld with ER505 as a filler material by GTAW process will produce better results.