Abstract
Copper alloys, combined with selective laser melting (SLM) technology, have attracted increasing attention in aerospace engineering, automobile, and medical fields. However, there are some difficulties in SLM forming owing to low laser absorption and excellent thermal conductivity. It is, therefore, necessary to explore a copper alloy in SLM. In this research, manufacturing feasibility and forming properties of Cu-4Sn in SLM were investigated through a systematic experimental approach. Single-track experiments were used to narrow down processing parameter windows. A Greco-Latin square design with orthogonal parameter arrays was employed to control forming qualities of specimens. Analysis of variance was applied to establish statistical relationships, which described the effects of different processing parameters (i.e., laser power, scanning speed, and hatch space) on relative density (RD) and Vickers hardness of specimens. It was found that Cu-4Sn specimens were successfully manufactured by SLM for the first time and both its RD and Vickers hardness were mainly determined by the laser power. The maximum value of RD exceeded 93% theoretical density and the maximum value of Vickers hardness reached 118 HV 0.3/5. The best tensile strength of 316–320 MPa is inferior to that of pressure-processed Cu-4Sn and can be improved further by reducing defects.
Highlights
Selective laser melting (SLM) is a unique additive manufacturing (AM) technology that enables us to produce dense metal parts by means of layer-by-layer construction using metal powders based on CAD models [1,2,3]
The Cu-4Sn bronze was selected for further investigation of microstructure and mechanical properties in SLM because it has the minimum casting shrinkage coefficient among non-ferrous metals and has relatively slight dendrite segregation among tin-copper alloys, as the segregation depends on the level of tin
The process chamber provides provides a closed environment filled by inert gas, such as nitrogen or argon, and the substrate a closed environment filled by inert gas, such as nitrogen or argon, and the substrate temperature can temperature can be chosen according to different materials
Summary
Selective laser melting (SLM) is a unique additive manufacturing (AM) technology that enables us to produce dense metal parts by means of layer-by-layer construction using metal powders based on CAD models [1,2,3]. In comparison with traditional manufacturing methods, SLM offers a wide range of advantages It can directly manufacture highly complex parts that are difficult or unable to be fabricated by conventional methods, with mechanical properties comparable to those of wrought materials. Copper alloys, compared with other metal alloys, exhibit moderate mechanical properties, high corrosion resistance, excellent electrical and thermal conductivity, as well as outstanding machinability and formability [9] As such, these alloys are widely used in electronics, machinery, aerospace, defense, and other industrial fields, such as heat exchangers for various types of equipment, high-precision springs and bearings, electronic connectors, plastic deformation tools, and propulsion devices in marine applications [10,11]. Fabrication methods of copper alloys are limited in conventional powder metallurgy technology, cold compaction, sintering, and infiltration These methods are not appropriate for manufacturing parts with intricate shapes. The Cu-4Sn bronze was selected for further investigation of microstructure and mechanical properties in SLM because it has the minimum casting shrinkage coefficient among non-ferrous metals and has relatively slight dendrite segregation among tin-copper alloys, as the segregation depends on the level of tin
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