Effect of thermal input mode on the microstructure evolution, mechanical properties, and electrochemical performance of laser powder bed fusion manufactured tungsten alloy

W–Ni–Fe alloys are widely used tungsten alloys, with laser powder bed fusion (LPBF) emerging as a promising method for producing high-quality components. Thermal input modes significantly influence LPBF component quality, yet their effects on forming quality, mechanical properties, and corrosion behavior in tungsten alloys remain underexplored. This study evaluates three thermal input modes—subarea distributed, long-range quasi-steady, and continuous repeated—on the forming quality, mechanical properties, and electrochemical corrosion behavior of 93 W alloys fabricated via LPBF. The relationships between the thermal input mode and surface morphology, densification, microhardness, compressive properties, and corrosion resistance were analyzed. The subarea distributed heat input mode proved optimal, achieving the highest density (98.7%), microhardness (520.24 HV0.2), ultimate compressive strength (2526.31 MPa), and elongation at fracture (33.61%). The specimens manufactured using this optimized mode exhibited superior corrosion resistance, characterized by the highest corrosion potential (−548.3 mV) and the lowest corrosion current density (2.165 μA cm2). In contrast, the continuous repeated heat input mode led to the lowest forming quality and mechanical properties due to higher porosity (0.27%) and more pronounced metallurgical defects, resulting in reduced compressive strength (2025 MPa) and corrosion resistance. The long-range quasi-steady mode showed intermediate performance between the two. This research clarifies the mechanisms by which the thermal input mode impacts metallurgical defects, mechanical performance, and corrosion resistance, offering valuable theoretical insights into the development of high-performance tungsten alloy components in laser additive manufacturing.