Influence of Mo Additive on Microstructure And Corrosion Behavior of Tc4 Metal-Cord Welding Overlay

Abstract

TC4 is a widely used α+β dual-phase titanium alloy with excellent properties. However, solid TC4 welding wires face challenges such as complex smelting, composition control issues, low deposition efficiency, and spattering, limiting their production potential. This study explores newly designed TC4 powder core welding wires, focusing on the impact of Mo addition on the mechanical properties and corrosion resistance of the cladded metal. The microstructure and corrosion morphology were characterized using OM、SEM、XRD and EDS. With increasing Mo content, the equiaxed grain size decreased. In the XY direction, the width of the α-Ti lamellae was smaller than in the Z direction for the same Mo content. Additionally, the aspect ratio of the α-Ti lamellae and the volume fraction of (α+β) phase were larger in the XY direction than in the Z direction under the same Mo content. The average microhardness at the top, middle, and bottom of the cladded metal showed an increasing trend. In the XY direction, the tensile strength increased from 1034 MPa to 1145 MPa, and the elongation after fracture decreased from 9.2% to 8.5%. In the Z direction, the tensile strength increased from 1010 MPa to 1069 MPa, and the elongation after fracture decreased from 10.8% to 8.7%. Electrochemical tests revealed that the self-corrosion potential increased from -0.732 mV to -0.557 mV, and the corrosion current density decreased from 3.008×10−6 A·cm2 to 8.058×10−7 A·cm2, indicating an improvement in corrosion resistance.

Keywords: Powder core welding wires, Mo addition, MICROSTRUCTURE, Corrosion resistance