Influence of Mo additive on microstructure and corrosion behavior of TC4 metal-cored welding overlay

Titanium alloy Ti–6Al–4V or TC4 is a α+β dual-phase titanium alloy, well-suited for use as weld overlays due to its excellent protective properties with excellent properties. However, the weld deposition method by 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 metal powder core welding wire, focusing on the impact of Mo addition on the mechanical properties and corrosion resistance of the cladded metals. The results showed that the addition of Mo reduced the α-Ti lamellae grain size along the thickness direction of TC4 weld overlay. The average microhardness of the TC4 cladding with 0.70 and 1.70 wt% Mo showed a general increase as compared to the control. Tensile strength also improved with Mo addition. In the XY direction, tensile strength increased from 1034 MPa to 1145 MPa, while elongation after fracture decreased from 9.2 % to 8.5 %. Similarly, in the Z direction, tensile strength increased from 1010 MPa to 1069 MPa, with elongation after fracture decreasing 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 cm 2 to 8.058 × 10 −7 A cm 2 , indicating an improvement in corrosion resistance. Therefore, the addition of Mo to TC4 weld overlays significantly enhances both the mechanical properties and corrosion resistance, making it a promising material for applications requiring improved performance in demanding environments.