Microstructure and properties of the membrane water-walls of boiler with Inconel 625 alloy surfacing layer

Abstract

The Inconel 625 alloy was surfaced on the water-walls tubes by MIG welding technique for the protection requirements of membrane water-walls of boiler. The microstructure, phase and chemical composition of the surfacing layer were analyzed. The results show that the microstructure of the surfacing layer is dendritic austenite and the essential elements of the surfacing layer are Ni, Cr, Mo and Fe. The test of the mechanical properties of the water-walls surfacing Inconel 625 alloy shows the interface of the surfacing layer and 20G matrix bonds well and the hardness of the surfacing layer is higher than that of the matrix. The tensile strength of water-walls of boiler with Inconel 625 alloy surfacing layer is up to 509 MPa, and its impact energy is 45 J, which indicates that the strength of the 20G matrix increases after surfacing Inconel 625, and its ductility is improved.