TEM AND FESEM ANALYSIS OF DISSIMILAR JOINTS OF INCOLOY 800 HT AND P91 STEEL ON GTAW PROCESS

Abstract

The present paper investigates the dissimilar joining of Incoloy 800 HT and P91 steel using gas tungsten arc welding process. Welding was carried out using two filler materials, namely, Inconel 82 and 9CrMoV-Nb. Welding speed, current and voltage were considered as input parameters. Microhardness, tensile strength and impact strength were measured as performance characteristics. Metallurgical aspects of dissimilar welds were analyzed on the basis of microstructure obtained by using optical microscope, high-resolution field emission scanning electron microscopy and transmission electron microscopy. The ferrite content was measured by using feritscope, and the elemental analysis was carried out with the help of X-ray energy dispersive spectrometer. It was found that the 9CrMoV-Nb filler material produced dissimilar weld with better mechanical properties than the dissimilar weld produced using Inconel 82 filler material.