Influence of Axial Magnetic Field Polarity on the Microstructure and Wear Behavior of High-Entropy Alloy Coatings Deposited by Cable-Type Wire GMAW

High-entropy alloy (HEA) coatings are widely recognized for their excellent hardness and wear resistance. Heterogeneous cabled wire welding (HCWW) combined with gas metal arc welding (GMAW) has emerged as an efficient approach for fabricating HEA coatings; however, severe arc instability inherent to HCWW often deteriorates coating quality. In this study, the effects of axial magnetic fields (AMFs) with different orientations on the HCWW–GMAW process were systematically investigated. High-speed imaging revealed that the HCWW arc without magnetic assistance exhibits pronounced instability, characterized by asymmetric morphology and rotational behavior. The application of AMFs significantly altered arc dynamics. An upward axial magnetic field (N-AMF, 2 mT) effectively suppressed arc rotation, resulting in a stable bell-shaped arc and more uniform heat input, whereas a downward axial magnetic field (S-AMF) caused arc contraction and promoted dendrite coarsening. Consequently, the N-AMF condition led to a refined and homogeneous microstructure, yielding a high microhardness of 825 ± 15 HV. Tribological tests demonstrated that the wear rate of the N-AMF-assisted coating was reduced by 55% compared with that produced by conventional GMAW. These results highlight that magnetic-field-induced arc stabilization plays a critical role in achieving high-performance HEA surface coatings.