Effects of direct hot isostatic pressing on microstructural, electrical and mechanical properties of selective laser melted pure copper

This study investigates how energy density and subsequent hot isostatic pressing (HIP) affect the density, microstructure, electrical conductivity, and mechanical properties of pure copper (Cu) components fabricated by selective laser melting (SLM). Components were produced at three calculated energy densities 3.11, 6.22, and 9.34 J·mm -3 and then subjected to a thermo-mechanical HIP treatment (600 °C, 2000 bar, 2 h). As the as-built energy density increased during the SLM process, lack-of-fusion defects and porosity were suppressed, and both density and conductivity improved (79.1 → 97.9 → 98.9 %); 49.8 → 90.5 → 98.1% IACS). The effect of HIP was then evaluated across all energy-density conditions. After HIP, all conditions achieved >99 % high density (8.88–8.93 g·cm -3 ) and converged to ∼100 % IACS, while mechanical properties became uniformly high (UTS ≈ 220–235 MPa, YS ≈ 110–120 MPa, elongation ≈ 40–50 %). Collectively, these findings indicate that, for pure copper despite the intrinsic difficulty of applying SLM applying an optimized HIP condition to builds produced across a broadened process window (including lower laser powers and higher scan speeds) provides an effective route to nearly pore-free, homogenized, high-density components. Such components combine excellent electrical conductivity with stable mechanical performance, enabling deployment in thermally and electrically demanding, high value applications.