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Materials Science in Additive Manufacturing Additive manufacturing of 316L-Cu alloys

A C

B

Figure 4. Compressive stress-strain and hardness behavior of 316L and Cu-alloyed compositions (A) Representative stress-strain curves for all three
compositions show similar behavior under uniaxial compression loading. (B) Vickers hardness measurements showed a slight reduction with Cu presence,
plotted as a three-point moving average. (C) Illustration of hardness measurement locations on a cylinder cross-section

previous findings in other studies of Cu-alloyed 316L SS-5Cu has also been reported in similar work involving
produced through traditional manufacturing methods. 316L-Cu alloys. 27-30 A possible cause for this shift could be
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Cu addition into 316L has also been achieved through residual stresses caused by substituting Cu atoms into the
powder bed fusion (PBF), another popular AM process, Fe lattice, leading to a change in lattice parameters due to
and exhibited similar Cu dissolution in a 316L matrix. the difference in atomic radius of the two elements.
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Although this study found similarly sized equiaxed Compressive stress-strain behavior (Figure 4) showed
structures for all three compositions, it has been reported that all compositions had similar compressive strength
that higher Cu loadings may lead to increased temperature values. A slight reduction in yield strength was observed
gradients due to the higher thermal conductivity of Cu over for SS-5Cu (317 ± 1 MPa) compared to 316L (334 ± 9 MPa)
316L (385 vs. ~20 W/m.K), causing grain refinement. 28 and SS-3Cu (329 ± 12 MPa). Similarly, a minor reduction
EDS mapping was conducted to determine the elemental in hardness was measured in the Cu compositions (183 ± 9
distribution across sample surfaces. As shown in Figure 2, and 186 ± 10 HV 0.2 for SS-3Cu and SS-5Cu, respectively)
the analysis confirmed the uniform distribution of Cu with compared to 316L (209 ± 12 HV 0.2). Previous studies have
no preferential concentrations in the grain structure. 316L, reported similar reductions in strength and hardness with
composed of approximately 18% Cr and 14% Ni, appeared Cu addition in samples produced by laser PBF (LPBF).
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to form a solid solution with Cu addition, as shown in This trend has also been recorded in alloys produced
previous works. 27,28 A homogenous Cu distribution ensures through forging, though the same study also demonstrated
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consistent mechanical and antibacterial properties. Phase a notable increase in strength and hardness after applying
analysis was performed using XRD (Figure 3), which a heat treatment cycle. Conversely, increases in strength
revealed an exclusive FCC austenite phase within the and hardness have been reported directly after production
detection limit across all compositions, with diffraction through PBF. 27,29 This property variation could be credited
peaks corresponding to the (111), (200), (220), and (311) to varying amounts of Cu and differing manufacturing
planes. The slight shift in peak positions for SS-3Cu and methods, leading to differences in the microstructure.

Volume 4 Issue 1 (2025) 7 doi: 10.36922/msam.7357