The present study investigates the wear properties of commercially pure titanium (CP-Ti) parts produced using selective laser melting (SLM) and casting. Scanning electron microscopy (SEM) ...investigations show that SLM-produced CP-Ti parts have martensitic (α΄) microstructure, whereas cast-produced CP-Ti samples exhibit plate-like (α) microstructure. SEM studies on the wear surfaces at moderate loads (15N) show shallow ploughing grooves at certain regions and some delamination cracks for both SLM and cast CP-Ti samples. On increasing the load to 30N, deeper ploughing grooves were observed in both samples along with delamination of material at certain regions. However, ploughing grooves were found to be very shallow in SLM samples compared with the cast parts. Although both SLM and cast CP-Ti exhibited similar wear mechanisms, SLM CP-Ti showed better wear resistance due to its martensitic microstructure, finer grain size and superior microhardness.
•Wear-properties of commercially pure-Ti prepared by SLM and casting processes.•Both samples show similar wear mechanisms.•SLM-processed sample show superior wear performance than cast specimens.•The superior wear properties are attributed to the martensitic microstructure.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Commercially pure titanium (CP-Ti) and Ti–TiB composite parts with three different porosity levels (i.e. 10%, 17% and 37%) were produced by selective laser melting (SLM). Scanning electron microscopy ...(SEM) investigations show that martensitic (α′) microstructure exists in SLM-processed CP-Ti parts, whilst SLM-processed Ti–TiB composites present needle-shape TiB particles distributed in α-Ti matrix. Mechanical properties of these porous samples decrease with porosity level increasing. The yield strength and elastic modulus of porous CP-Ti parts range 113–350MPa and 13–68GPa respectively, which are much lower than those for porous Ti–TiB counterparts (234–767MPa and 25–84GPa respectively) mainly due to the strengthening effect induced by TiB particles in Ti–TiB samples. Compression stress–strain curves of 37% porous CP-Ti parts show a typical three-stage behavior of ductile porous metals. Also, the elastic moduli of both 37% porous CP-Ti and Ti–TiB samples are similar to that of human bone. SEM investigations of the porous CP-Ti samples after compression testing show that no crack presents until 50% compressive strain and most of deformation is absorbed by porous areas. In contrast, μ-CT investigations indicate that all porous Ti–TiB samples fail at early stages of compression testing due to cracks resulting from insufficient ductility of struts of porous areas, because they are not able to accommodate high strains of the deformation at high strengths.
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IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Highly-dense bulk Cu–10Sn bronze specimens have been fabricated by selective laser melting (SLM) and their (micro)structure and mechanical properties have been investigated and compared with the ...corresponding material produced by casting. Room-temperature tensile tests reveal that yield and ultimate strengths increase from 120 and 180MPa for the cast samples to 220 and 420MPa for the specimens processed by SLM. Material strengthening is accompanied by a significant improvement of ductility, which increases from 7 to 17%. This behavior can be ascribed to the refined microstructure of the SLM material resulting from the high cooling rate imposed by laser processing, further demonstrating the effectiveness of SLM for the production of materials with enhanced mechanical performance.
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•Highly-dense Cu–10Sn bronze specimens fabricated by selective laser melting (SLM).•Refined microstructure of SLM material compared to corresponding cast samples.•Improved yield and ultimate strengths, and ductility with respect to cast material.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Laser welding of Al0.5CoCrFeNi high-entropy alloy has been studied in detail. Base metal (BM) shows equiaxed grains with three different regions; (a) Cr–Fe rich, (b) Al–Ni rich phases and (c) Al-rich ...particle. Laser welding has resulted in evolution of columnar dendritic microstructure with dissolution of Al rich particles in the weld metal (WM), where dendrites are Cr–Fe rich and interdendrites are Al–Ni rich regions. The corrosion experiment shows higher corrosion current density (2.83 × 10−5 mA/cm2) in WM than the BM (8.63 × 10−6 mA/cm2) implies higher corrosion rate. However, the WM exhibits higher (nobler) corrosion potential as compared to BM. Due to this nobler potential, WM acts as the cathode and the BM act as an anode when weldment (BM + WM) is analyzed. Hence, the weldment (BM + WM) exhibits lower corrosion current density (4.11 × 10−6 mA/cm2) like BM.
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•Laser welding was effectively employed for welding Al0.5CoCrFeNi high-entropy alloys (HEA).•Corrosion behavior of high-entropy alloy weld was studied for first time.•Weldment show better corrosion resistance in aqueous medium than the base metal.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Pronounced crystallographic texture, characteristic for the parts manufactured by selective laser melting, is eliminated upon addition of TiB2 microparticles to Al-12Si powder. Due to the wetting of ...TiB2 ceramic by Al-12Si melt and a high inoculation efficiency, a homogeneous microstructure consisting of fine equiaxed grains with random crystallographic orientation is formed by SLM processing of the Al-12Si/TiB2 powder mixture. The Al-12Si/TiB2 samples exhibit enhanced yield strength and microhardness, compared to the TiB2-free Al-12Si samples produced at the same SLM conditions.
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•Good wettability and high work of adhesion for liquid Al-12Si and TiB2 ceramic.•TiB2 efficient in texture elimination and grain refinement by SLM of Al-12Si.•Enhanced mechanical properties for Al-12Si/TiB2 samples fabricated by SLM.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Al-12Si samples were fabricated by selective laser melting. Different processing parameters, including four different hatch styles, as well as contour and base plate heating, were employed to ...evaluate their impact on the room temperature tensile properties. The samples with different hatch styles show similar crystallite sizes and lattice parameters of Al and comparable amount of free residual Si, but different levels of texture. The yield strength (YS) varies between 235 MPa and 290 MPa, the ultimate tensile strength (UTS) between 385 MPa and 460 MPa and the tensile ductility ranges between 2.8% and 4.5%. Similarly, the samples produced with and without contour show differences in their tensile properties. Base plate heating was employed with three different temperatures and the samples display improved plasticity with increasing base plate temperature (BP 473 K, 573 K and 673 K samples show a ductility of 3.5%, ∼3% and 9.5%, respectively). The results indicate that the room temperature tensile properties can be tuned (between YS: 115 MPa–290 MPa, UTS: 220 MPa–460 MPa and ductility: 2.8%–9.5%) in-situ during the selective laser melting process giving an opportunity to define the mechanical properties of the SLM parts to suit their service requirements.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Selective laser melting was used to in-situ fabricate Al-xCu (x = 4.5, 6, 20, 33 and 40 wt%) samples from mixtures of Al-4.5Cu/Cu powders. The insufficient Cu solute diffusion during the ...layer-by-layer processing results in an inhomogeneous microstructure around the introduced Cu powders. The boundaries between the molten pools of all alloys display different microstructural characteristics, indicating the occurrence of both high- and low-cooling-rate zones as well as heat-affected zones. With increasing Cu content, the Al2Cu phase in the alloys increases, improving the strength of the material. Al-33Cu with a nano-eutectic microstructure exhibits the highest compressive strength exceeding 1000 MPa.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The effect of scanning strategy and heat-treatment on the tribological properties of Al-12Si fabricated using selective laser melting (SLM) were evaluated and compared with their cast counterparts ...(CC). The SLM sample shows a mesostructure and in addition, the microstructure consists of the Al rich cells surrounded by Si network in the fine cellular structure. Annealing leads to the precipitation of Si and disintegration of the cellular structure, resulting in the reduction of hardness. The as-prepared SLM specimens show the least wear rate compared to heat treated SLM and CC specimens. SLM specimens built with single melt (SM) and checkerboard (CB) scanning strategies have similar hardness, the wear rate of in the former is significantly higher due to high porosity in it.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Additive manufacturing (AM) has emerged as an alternative tool to overcome the challenges in conventionally processed metallic components. It is gaining wide acceptability because of the superior ...properties of the manufactured components compared to their wrought processed counterparts. Among the available AM processed materials, austenitic stainless steel 316L is widely explored wherein an excellent strength-ductility trade-off has been reported. However, the mechanisms underlying fracture toughness of AM stainless steel 316L vis-à-vis wrought processed stainless steel 316L material are not yet explored. The present investigation is aimed at examining the mechanisms accountable for the fracture toughness of AM processed stainless steel 316L. The specimens are produced by two different AM techniques namely, selective laser melting (SLM) and wire arc additive manufacturing (WAAM). A wrought processed stainless steel 316L was used as a control material for comparison. Three-point bending tests were carried out on fatigue pre-cracked single edge notched specimens and crack initiation fracture toughness was evaluated. Digital image correlation was used for strain analysis and to monitor crack propagation. The SLM manufactured sample has shown higher fracture toughness whereas WAAM has exhibited nearly the same fracture toughness when compared to the wrought processed stainless steel 316L sample. Microstructure of fractured samples consists of a significantly higher twin density and a higher propensity of dislocation slip was observed in the SLM sample than the other two. It has been argued that a very fine cellular structure, minimized process-induced defects, enhanced twin density led to promising toughness in the SLM processed stainless steel 316L.
As a new preparation technique, selective laser melting (SLM) is applied to fabricate an electronic packaging candidate material, i.e., the Al-50Si alloy. The microstructures of the as-cast and the ...SLM Al-50Si alloys are investigated. The influences of solid solubility on the coefficient of thermal expansion (CTE) of the as-SLM and the heat-treated alloys are investigated. The primary Si can be significantly modified after SLM processing. Moreover, a CTE peak can be observed for the SLM alloy due to the formation of a supersaturated Al(Si) solid solution, which disappears after heat treatment due to Si precipitation. Furthermore, the relationship and differences between theoretical models and the experimentally determined CTE for the Al-50Si alloy will be discussed.
•A new electronic packaging material of Al-50Si alloy is prepared by SLM technique.•The correlation between microstructure and CTE of SLM Al-50Si alloy is investigated.•The precipitation of Si particles from the Al matrix leads to a CTE peak.•The experimental CTE lies between the SL and the Turner model after heat treatment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
