Selective Laser Melting of Al-7Si-0.5 Mg-0.5Cu: Effect of Heat Treatment on Microstructure Evolution, Mechanical Properties and Wear Resistance
TL;DR: In this paper, the effects of solution treatment, quenching, and artificial aging on the microstructural evolution, as well as mechanical and wear properties, have been investigated, and the as-prepared samples show a heterogeneous cellular microstructure with two different cell sizes composed of α-Al and Si phases.
Abstract: Al-7Si-0.5 Mg-0.5Cu alloy specimens have been fabricated by selective laser melting (SLM). In this study, the effects of solution treatment, quenching, and artificial aging on the microstructural evolution, as well as mechanical and wear properties, have been investigated. The as-prepared samples show a heterogeneous cellular microstructure with two different cell sizes composed of α-Al and Si phases. After solution-treated and quenched (SQ) heat treatment, the cellular microstructure disappears, and coarse and lumpy Si phase precipitates and a rectangular Cu-rich phase were observed. Subsequent aging after solution-treated and quenched (SQA) heat treatment causes the formation of nanosized Cu-rich precipitates. The as-prepared SLMs sample has good mechanical properties and wear resistance (compressive yield strength: 215 ± 6 MPa and wear rate 2 × 10–13 m3/m). The SQ samples with lumpy Si particles have the lowest strength of 167 ± 13 MPa and the highest wear rate of 6.18 × 10–13 m3/m. The formation of nanosized Cu-rich precipitates in the SQA samples leads to the highest compressive yield strength of 233 ± 6 MPa and a good wear rate of 5.06 × 10–13 m3/m.
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TL;DR: In this article , a new class of martensitic stainless steel, namely 06Cr15Ni4CuMo, with applications in marine engineering, was processed by using selective laser melting (SLM).
Abstract: A new class of martensitic stainless steel, namely 06Cr15Ni4CuMo, with applications in marine engineering, was processed by using selective laser melting (SLM). A body-centered cubic martensitic microstructure was observed, and the microstructure was compared with wrought 410 martensitic stainless steel. The SLM-processed sample showed a hardness of 465 ± 10 HV0.5, which was nearly 115 HV0.5 less than the wrought counterpart. Similarly, the SLM-processed sample showed improved YS and UTS, compared with the wrought sample. However, reduced ductility was observed in the SLM-processed sample due to the presence of high dislocation density in these samples. In addition, 71% volume high-angle grain boundaries were observed, corroborating the high strength of the material. The corrosion behavior was investigated in seawater, and the corrosion resistance was found to be 0.025 mmpy for the SLM-processed 06Cr15Ni4CuMo steel and 0.030 mmpy for wrought 410 alloys, showing better corrosion resistance in the SLM-processed material.
4 citations
TL;DR: In this paper , the tribological behavior of laser powder bed fusion (LPBF) A357 alloy is assessed as a function of both printing parameters and heat treatment conditions, applying a novel T6 based on rapid solution followed by artificial aging, which improves the strength-ductility balance.
2 citations
01 Aug 2022-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper , an Al-12Si-Ti alloy was synthesized by selective laser melting (SLM) processing with a powder mixture consisting of Al−12Si and 1 wt% of Ti nanoparticles to improve its thermal stability at midtemperatures.
Abstract: Due to the rapidly degradative mechanical performance of selective laser melted (SLM) Al–12Si at elevated temperatures, an Al–12Si–Ti alloy was synthesized by SLM processing with a powder mixture consisting of Al–12Si and 1 wt% of Ti nanoparticles to improve its thermal stability at mid-temperatures (573 K). The results demonstrate that the addition of Ti nanoparticles (i) enlarges the parameter window of SLM processing (power inputs of 200–350 W and scanning speeds of 600–1600 mm/s), (ii) stimulates a columnar to equiaxed transition and refinement of grains (average grain size decreases from 9.0 μm to 1.5 μm), (iii) forms Al 3 Ti phase improving the thermal stability of Al–Si eutectic cell structure, and (iv) partially suppresses the precipitation of Si phase and coarsening of cell structure at elevated temperatures. These features lead to an improved yield strength of SLM Al–12Si–Ti compared with SLM Al–12Si. Specifically, SLM Al–12Si–Ti annealed at 573 K possesses a higher yield strength (297 ± 10 MPa) than SLM Al–12Si (207 ± 9 MPa) annealed at the same conditions. This study will pave the way for the design and synthesis of SLM Al alloys with improved structural and mechanical stability by minor alloying via nanoparticle addition. • Al–12Si–Ti alloy with a broad processing window is designed and fabricated by selective laser melting (SLM). • SLM Al–12Si–Ti alloy has high microstructural stability and mechanical performance under an annealing temperature of 573K. • Addition of Ti can promote the columnar to equiaxed transition and refinement of grains. • Addition of Ti leads to the formation of Al 3 Ti precipitates enhancing the thermal stability of eutectic Al–Si cell. • Addition of Ti can suppress microstructural change, thereby maintaining a higher strength than Al–12Si annealled at 573K.
2 citations
TL;DR: In this article , the relationship between processing parameters, microstructure, and mechanical properties of Al-8.3Fe-1.8Si alloy processed by laser powder bed fusion is seldom studied.
Abstract: The relationship between processing parameters, microstructure, and mechanical properties of Al-8.3Fe-1.3V-1.8Si alloy processed by laser powder bed fusion is seldom studied. Therefore, fully dense alloys with two parameters were selected to investigate this key issue. The results show that the alloy with low power and scanning speed (S200) shows fan-shell-shaped melt pools and laser tracks while another (S350) shows a deeper and wider melt pool. Both alloys obtain a heterogeneous microstructure without a secondary phase in melt pool (MP) and a nano-sized phase in melt pool boundary (MPB). The difference between solid-solution strengthening and Orowan strengthening in MP and MPB contributes to the difference in compressive yield strength (S200: 380 ± 14 MPa and S350: 705 ± 16 MPa), and heterogeneous nano-hardness results in different crack behaviours and failure strains. This work indicates that adjusting processing parameters is an effective method to control microstructure and mechanical properties of this alloy.
1 citations
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TL;DR: In this paper, the high thermal gradients occurring during SLM lead to a very fine microstructure with submicron-sized cells, which can be modified to a weak cube texture along the building and scanning directions when a rotation of 90° of the scanning vectors within or between the layers is applied.
1,431 citations
TL;DR: In this article, the authors describe which types of laser-induced consolidation can be applied to what type of material, and demonstrate that although SLS/SLM can process polymers, metals, ceramics and composites, quite some limitations and problems cause the palette of applicable materials still to be limited.
1,241 citations
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TL;DR: An analytical model for predicting the yield strength of particulate-reinforced metal matrix nanocomposites has been developed in this article, where the strengthening effects involving Orowan strengthening effect, enhanced dislocation density due to the residual plastic strain caused by the difference in the coefficients of thermal expansion between the matrix and particles, and loadbearing effect have been taken into account in the model.
1,042 citations