Hot wire-assisted gas metal arc welding of hypereutectic FeCrC hardfacing alloys: Microstructure and wear properties

Abstract

The deposition welding of hypereutectic FeCrC hardfacing alloys requires low dilution rates in order to ensure the specified chemical composition and thus the precipitation of primary M7C3 (M=Fe, Cr) carbides, which affect the abrasive wear resistance of the hardfacing. Because dilution is critical in determining the above mentioned criteria during surfacing, the development of deposition welding processes with reduced thermal impact and hence reduced dilution of the base material is a main focus of current research. For the purpose of improving the processing properties of gas metal arc welding (GMAW) in hardfacing applications, the potential of an additional hot wire (HW-GMAW) was investigated. The application of a hot wire enabled the independent adjustment of the deposition and dilution rates. Furthermore, the dilution and microstructural properties could be adjusted independently of the deposition rate. HW-GMAW enabled hypereutectic solidification in the first layer, even at very high deposition rates of 9kg/h. In this manner, a primary M7C3 carbide content reaching 17% by area (A%) was achieved in the first layer. In comparison to single-layer GMAW overlays the wear properties were improved.