OBRABOTKAMETALLOV Vol. 23 No. 3 2021 MATERIAL SCIENCE EQUIPMENT. INSTRUMENTS 7 2 5 low ability to absorb electron beam radiation (~2 %) and high thermal conductivity (400 W·m−1·K−1) of copper and copper alloys mean that high heat input values are required during the manufacturing process. It should be noted that the large difference in the thermal expansion coefficient between these materials leads to the accumulation of deformation and high internal stress at the interface, which can ultimately lead to cracking [15]. Due to the aforementioned problems, the fabrication of bimetallic specimens with different interface designs between iron and copper alloys is challenging [16]. To manufacture a defect-free multi-component specimen when alternating dissimilar wires during printing, it is necessary to control the thermal conditions so that the wire of one material has time to melt, while the wire of the other material does not spread, creating defects and disrupting the geometry of the product. For this, it is necessary to take into account the physical and mechanical properties and calculate the values of heat input for each type of structural design and each material used, as will be shown below. Fig. 2. Schematic of possible multi-component sample configurations fabricated by additive manufacturing: a – sharp interface; b – smooth interface; c – heterogeneous structure; d – layered composite Ta b l e 3 Physical and mechanical properties of the materials used Material Tm, °C ρ, kg/m3 C, J / (kg · °C) λ, W / (m · °C) α, 1 / °C AISI 321 1,420 7,920 462‑596 15‑26 16.6‑19.3 M1 1,083 8,940 390 387 16.7 0.09 C-2 Mn-Si 1,450‑1,520 7,850 496‑676 33‑27 11.5‑12.3 Cu-9 Al-2 Mn 1,060 7,630 461 71.4 17
RkJQdWJsaXNoZXIy MTk0ODM1