<p>This paper introduces an active thermal management (ATM) system mitigating the thermal stresses associated with WA-DED of HSLA steel/CuSi/aluminum (Al) trimetallic structures. The study aims to regulate the formation of detrimental intermetallic phases at the CuSi/Al interface. Preliminary trials included quantitative porosity analysis and qualitative interfacial cracking inspection to obtain the appropriate processing parameters of Al-5356 on CuSi substrates. The developed ATM system enabled multi-layer deposition of trimetallic HSLA steel/CuSi/Al-5356 structures. Comprehensive microstructural analysis revealed a continuous 2&#xa0;µm film of η-AlCu intermetallic phase along the CuSi/Al-5356 interface, and a 40&#xa0;µm mixed zone of eutectic (α-Al + θ-Al₂Cu) and intermetallic phases. Hardness measurement along the building direction passing through the interface between CuSi and Al layers revealed an abrupt increase in hardness up to (350 HV), which confirmed the formation of hard intermetallic phase along the CuSi/Al interface. Tensile testing of the trimetallic material along the building direction revealed a significant reduction in strength and ductility compared to the transverse tested single material samples due to the induced influence of the brittle intermetallic layer formed at the CuSi/Al interface.</p> Graphical abstract <p></p>