<p> A fully pearlitic matrix can be obtained by alloying elements that promote the pearlitic eutectoid reaction, with copper being one of the most widely employed stabilizers. This study investigates the effect of Cu addition on the microstructure and tribological behavior of as-cast FCD700 ductile cast iron without subsequent heat treatment. While previous research has largely focused on Cu in combination with alloying elements such as Sn, Mn, and Cr, or in powder metallurgy systems, the present work clarifies the role of Cu alone in pearlite stabilization and the improvement of hardness and wear resistance. Alloys containing 0.0, 1.0, 2.0, and 3.0 wt.% Cu were produced by induction melting and shell mold casting, and characterized using optical microscopy, SEM-EDS, interlamellar spacing analysis, hardness, and dry sliding wear tests. Results show that Cu addition up to 2.0 wt.% markedly increased the pearlite fraction, thereby enhancing matrix hardness. Consistently, both friction coefficient and wear volume decreased with Cu addition up to this level. However, at 3.0 wt.% Cu, performance deteriorated due to to solubility limit exceedance and Cu segregation, which promoted microstructural instability. Furthermore, interlamellar spacing varied nonlinearly with Cu content, suggesting that multiple factors including segregation and morphological changes gonern the observed behavior. Overall, Cu is confirmed as an effective pearlite-stabilizing element in as-cast FCD700 ductile iron, with 2.0 wt.% identified as the optimal composition for achieving improved hardness and wear resistance. These findings provide useful guidance for alloy design in tribological applications.</p>