<p>Material extrusion additive manufacturing of metals (MEX/M) often suffers from residual porosity after printing and pressureless sintering, limiting mechanical performance. This study investigates the influence of boron (B) addition (0, 0.3 and 0.6&#xa0;wt%) and sintering temperature (1200, 1250 and 1300&#xa0;°C) on the densification, microstructure, and wear behaviour of filament-based MEX/M-fabricated 316L stainless steel. B promotes liquid-phase sintering through the formation of core–shell inclusions and Cr₂B-based liquid phases, leading to enhanced densification at elevated sintering temperatures. Increased B content significantly raises hardness, primarily governed by the extent of Cr₂B formation. Under dry reciprocating wear, the coefficient of friction (COF) decreases with increasing sintering temperature, while B addition produces a temperature-dependent effect, increasing friction at intermediate temperatures but reducing it at higher temperatures. Wear resistance improves consistently with both increasing B content and sintering temperature, with optimal performance achieved at moderate to high B levels under high-temperature sintering conditions. The dominant wear mechanism transitions from adhesive–oxidative to abrasive with increasing B content and sintering temperature. Overall, the improved wear resistance is attributed to enhanced load-bearing capacity and microstructural strengthening associated with B-assisted liquid-phase sintering. These results highlight the effectiveness of B addition as a strategy for improving the tribological performance of MEX/M 316L stainless steel.</p> Graphical Abstract <p></p>