SLM process parameters development of Cu-alloy Cu7.2Ni1.8Si1Cr

Abstract

Purpose Materials with a high thermal conductivity, such as Cu-alloys hold the most interest to the plastic moulding industry. Additive manufacturing (AM), especially selective laser melting (SLM) of metals, allows the production of parts with complicated internal cooling and increased production efficiency. The portfolio of alloys for metal AM is limited and still missing process parameters for the processing of copper alloys. This paper aims to preview the process parameters of high-strength alloy Cu7.2Ni1.8Si1Cr processed by SLM. Design/methodology/approach An experimental approach is adopted to investigate porosity and mechanical properties of SLM specimens and its comparison with standard material AMPCOLOY 944. Optimization of porosity was performed using line and cube specimens; mechanical properties and microstructure were evaluated by tensile testing and metallography. Findings Optimum processing parameters for fabrication of Cu-alloy specimens with a relative density of 99.95 per cent were identified, and no cracks were detected. Mechanical testing of SLM specimens showed the ultimate tensile strength, proof stress of 0.2 and elongation of 380, 545 MPa and 16.9 per cent. The alloy is suitable for laser AM, thanks to its processability at a relatively high laser scanning speeds and thus its promising price of part/costs ratio. Research limitations/implications The paper describes the initial state of research – the follow-up tests focussed on mechanical testing, fatigue and statistical evaluation need to be conducted. The process parameters are developed only for bulk geometry – optimal setup for lattice structures and thin walls has not been explored yet. Practical implications The research findings in this work could be used for production of 3D printed parts and after the tuning of additional parameters, e.g. for up- and down-skin zones, could be used for special application such as energy exchange. Originality/value This work produces the processing of new material suitable for laser AM. Cu7.2Ni1.8Si1Cr alloy could be the prospective material from the group of Cu alloys suitable for moulds manufacturing and thermal applications.

Additive manufacturing of CuCr1Zr by development of a gas atomization and laser powder bed fusion routine

“…Similar results were found in Cu-Cr alloys with Cr contents by 20 wt.% and 25 wt.% [30]. For a Cu7.2Ni1.8Si1Cr provided by Sandvik Osprey Ltd., a relative density of 99.9% without any cracks was achieved [31].…”

Thermal conductivity of Cu7.2Ni1.8Si1Cr copper alloy produced via SLM and ability of thin-wall structure fabrication

“…Thin walls of varying thicknesses (from 0.4 mm to 3 mm) were successfully produced from C18400 copper alloy with a relative density of 96.74 % under proper forming parameters [4]. Paloušek et al [11] and investigated process parameters of Cu7.2Ni1.8Si1Cr copper alloy. Klimek [12] studied the influence of SLM process parameters on the wall thickness and surface quality.…”

“…The copper powder Cu7.2Ni1.8Si1Cr was produced by Sandvik Osprey Ltd. The powder morphology was evaluated in the study of Paloušek et al [11] based on the laser diffraction analysis and showed mainly a spherical shape of the particles. The powder particles had a large variability in size with an average value of 22.9 μm and 90 % were up to 38.6 μm.…”

“…All three parts were produced under the process parameters developed by the Institute of Machine and Industrial Design, BUT Brno, in particular described in the study of Paloušek et al [11]. A powder layer thickness of 50 μm was used during the production under an inert atmosphere of nitrogen.…”

“…As a result of sequential field scanning, the thermal energy of the high power laser is distributed and therefore diminishing the residual mechanical stresses. Particularly also results into a higher relative density of the consolidated material [11]. The ''Offset filling'' scanning strategy was used for the support structures and the cylinder web of 0.15 mm thickness, Figure 2, b).…”