Microstructure, Mechanical Performance, and Corrosion Behavior of Electron Beam Welded Thick Incoloy 825 Joints

Abstract

This work mainly studies the microstructure and mechanical properties of Incoloy 825 electron beam welded joints at different temperatures along with their electrochemical corrosion behavior. Two thick Incoloy 825 plates are joined by electron beam welding. The microstructure of the welded joints is analyzed by optical microscopy, scanning electron microscopy and energy-dispersive spectroscopy. The welded joints primarily consist of equiaxed crystals and columnar crystals. Compared with the base metal, there is no obvious variation in the elemental distribution in the weld zone. Microhardness tests are conducted in different regions of the welded joints and base metal, and the results show that the microhardness value of the weld zone is approximately the same as that of the base metal (approximately 180–210 Hv). Thus, the microhardness of the weld zone and the base metal is almost the same. Moreover, tensile tests at 25 °C and 600 °C are conducted in the weld zone, and the results show that the tensile strength and yield strength of the weld joints are roughly similar under the two different conditions. The electrochemical test in an acidic solution at pH = 3 shows that the weld zone has good corrosion resistance.