scholarly journals Investigation of the Possibility of Tailoring the Chemical Composition of the NiTi Alloy by Selective Laser Melting

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1470
Author(s):  
Evgenii Borisov ◽  
Kirill Starikov ◽  
Anatoly Popovich ◽  
Tatiana Tihonovskaya
Keyword(s):  
Energy Density ◽  
Selective Laser Melting ◽  
Laser Processing ◽  
Niti Alloy ◽  
Nickel Content ◽  
Energy Parameter ◽  
High Energy ◽  
Single Treatment ◽  
Technological Parameters ◽  
Laser Melting

In this work a study of the selective laser melting process of two NiTi alloys of equiatomic, and rich Ni composition were conducted. A study of the influence of the technological parameters on the alloy density was carried out. Values of technological parameters were obtained to ensure production of samples with the lowest number of defects. When using process parameters with the same energy density but different values of the constituent technological parameters, the amount of nickel carried away by evaporation changed insignificantly. An increase in the energy density led to an increase in the amount of nickel carried away, causing final samples with lower Ni content. When using multiple laser processing in the low-energy parameter set, it was possible to achieve a decrease in the nickel content in the alloy, similar to that with single high-energy processing. DSC studies showed a significant increase in transformation temperatures upon repeated laser processing due to the higher evaporation of nickel. The use of double laser treatment gave a decrease in the final density of the sample compared to a single treatment, but its value is still higher than when using a single treatment with a higher energy density.

scholarly journals Influence of Selective Laser Melting Technological Parameters on the Mechanical Properties of Additively Manufactured Elements Using 316L Austenitic Steel

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1449 ◽  
Author(s):  
Janusz Kluczyński ◽  
Lucjan Śnieżek ◽  
Krzysztof Grzelak ◽  
Jacek Janiszewski ◽  
Paweł Płatek ◽  
...  
Keyword(s):  
Energy Density ◽  
Selective Laser Melting ◽  
Dynamic Testing ◽  
Positive Impact ◽  
Image Correlation ◽  
Material Strength ◽  
Compression Tests ◽  
Dynamic Tests ◽  
Technological Parameters ◽  
Laser Melting

The main aim of this study was to investigate the influence of different energy density values used for the additively manufactured elements using selective laser melting (SLM).The group of process parameters considered was selected from the first-stage parameters identified in preliminary research. Samples manufactured using three different sets of parameter values were subjected to static tensile and compression tests. The samples were also subjected to dynamic Split–Hopkinson tests. To verify the microstructural changes after the dynamic tests, microstructural analyses were conducted. Additionally, the element deformation during the tensile tests was analyzed using digital image correlation (DIC). To analyze the influence of the selected parameters and verify the layered structure of the manufactured elements, sclerometer scratch hardness tests were carried out on each sample. Based on the research results, it was possible to observe the porosity growth mechanism and its influence on the material strength (including static and dynamic tests). Parameters modifications that caused 20% lower energy density, as well as elongation of the elements during tensile testing, decreased twice, which was strictly connected with porosity growth. An increase of energy density, by almost three times, caused a significant reduction of force fluctuations differences between both tested surfaces (parallel and perpendicular to the building platform) during sclerometer hardness testing. That kind of phenomenon had been taken into account in the microstructure investigations before and after dynamic testing, where it had been spotted as a positive impact on material deformations based on fused material formation after SLM processing.

scholarly journals Investigation of the Effects of an Intense Pulsed Ion Beam on the Surface Melting of IN718 Superalloy Prepared with Selective Laser Melting

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1178
Author(s):  
Min Min ◽  
Shuiting Ding ◽  
Xiao Yu ◽  
Shijian Zhang ◽  
Haowen Zhong ◽  
...  
Keyword(s):  
Energy Density ◽  
Selective Laser Melting ◽  
Ion Beam ◽  
Pulse Length ◽  
High Energy ◽  
Surface Melting ◽  
High Energy Density ◽  
Irradiation Effect ◽  
Laser Melting ◽  
In718 Superalloy

Intense pulsed ion beam irradiation on IN718 superalloy prepared with selective laser melting as an after-treatment for surface melting is introduced. It is demonstrated that intense pulsed ion beam composed of protons and carbon ions, with a maximum current density of 200 A/cm2 and a pulse length of 80 ns, can induce surface melting and the surface roughness changes significantly due to the generation of micro-defects and the flow of the molten surface. Irradiation experiments and thermal field simulation revealed that the energy density of the ion beam plays a predominant role in the irradiation effect—with low energy density, the flow of molten surface is too weak to smooth the fluctuations on the surface. With high energy density, the surface can be effectively melted and smoothened while micro-defects, such as craters, may be generated and can be flattened by an increased number of pulses. The research verified that for the surface melting with intense pulsed ion beam (IPIB), higher energy density should be used for stronger surface fluidity and a greater pulse number is also required for the curing of surface micro-defects.

scholarly journals Influence of Selective Laser Melting Technological Parameters on the Mechanical Properties of Additively Manufactured Elements Using 316L Austenitic Steel

2020 ◽  
Author(s):  
Janusz Kluczyński ◽  
Lucjan Śnieżek ◽  
Krzysztof Grzelak ◽  
Jacek Janiszewski ◽  
Paweł Płatek ◽  
...  
Keyword(s):  
Energy Density ◽  
Selective Laser Melting ◽  
Dynamic Testing ◽  
Positive Impact ◽  
Image Correlation ◽  
Material Strength ◽  
Compression Tests ◽  
Dynamic Tests ◽  
Technological Parameters ◽  
Laser Melting

The main aim of this study is to investigate the optimization of the technological process for selective laser melting (SLM) additive manufacturing. The group of process parameters considered was selected from the first-stage parameters identified in preliminary research. Samples manufactured using three different sets of parameter values were subjected to static tensile and compression tests. The samples were also subjected to dynamic Split–Hopkinson tests. To verify the microstructural changes after the dynamic tests, microstructural analyses were conducted. Additionally, the element deformation during the tensile tests was analyzed using digital image correlation (DIC). To analyze the influence of the selected parameters and verify the layered structure of the manufactured elements, sclerometer scratch hardness tests were carried out on each sample. Basing on the research results it was possible to observe the porosity growth mechanism and its influence on the material strength (including static and dynamic tests). Parameters modifications that caused 20% lower energy density, elongation of the elements during tensile testing decreased twice, which was strictly connected with porosity growth. An increase of energy density by almost three times caused a significant reduction of force fluctuations differences between both tested surfaces (parallel and perpendicular to the building platform) during sclerometer hardness testing. That kind of phenomenon had been taken into account in the microstructure investigations before and after dynamic testing where it had been spotted a positive impact on material deformations based on fused material grains formation after SLM processing.

Selective Laser Melting of Mechanically Alloyed Metastable Al5Fe2 Powders

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Hugo Montiel ◽  
Ben Xu ◽  
Jianzhi Li
Keyword(s):  
Aluminum Alloys ◽  
Energy Density ◽  
Selective Laser Melting ◽  
Laser Power ◽  
Laser Scanning ◽  
Laser Energy ◽  
Scanning Speed ◽  
High Energy ◽  
Laser Energy Density ◽  
Laser Melting

Aluminum alloys, which are high-strength lightweight materials, were processed by selective laser melting (SLM) with high-energy consumption and poor finish due to quick heat dissipation. Previous investigations reported that SLM with 300 W laser power and 500 mm/s scanning speed can process the aluminum alloys, such as Al-Si12 and AlSi10Mg. This work aims to process the powders to alter their properties and to reduce the laser intensity required in the process, and it also reports that the SLM-processed Al–Fe alloys utilize the metastable alloy by mechanical alloying (MA). The elemental Al and Fe powders were first alloyed in a ball mill in a relative short time period (∼15 h) employing high milling intensities, high ball-to-powder ratio (≥20:1), and high milling velocities (≥400 rpm), which produced fine metastable Al–Fe powders, and these powders were processed later by the SLM. The optimum laser power, the scanning speed, hatch distance, and substrate temperature were investigated by a series of experiments. Experimental results indicated that decreasing the laser energy density while increasing the laser scanning speed can benefit for smoother laser hatch lines, and the metastable Al5Fe2 alloy powders can be processed and stabilized under a 200-W laser energy density and a scanning speed of 1000 mm/s. It is expected that the combination of pre-excited materials in a metastable phase will open a new window to optimize the SLM process for aluminum alloys and other metallic alloys.

Main Defects Observed in Titanium GRADE II and 316L Stainless Steel Elements Obtained by Selective Laser Melting

2020 ◽  
Vol 308 ◽  
pp. 33-50
Author(s):  
Anna Woźniak ◽  
Marcin Adamiak
Keyword(s):  
Stainless Steel ◽  
Energy Density ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Defect Formation ◽  
Pure Titanium ◽  
Parameters Optimization ◽  
Laser Melting ◽  
Grade Ii ◽  
Titanium Grade

Selective Laser Melting SLM is one of the most popular three dimensional printing methods, which can be used for manufactured real elements (with high geometrical complexity) in many application, such as medicine, automotive or aerospace industries. The SLM final parts are characterized by high mechanical properties and satisfactory physicochemical properties. However, the properties of parts depend of process parameters optimization. In this paper, effects of processing parameters, such as laser power P, scanning speed SP, layer thickness t or point distance PD on defect formation and relative densities of manufactured elements are explored. For the purpose the stainless steel 316L and pure titanium Grade II are used. The process optimization were carried out according to the formula of energy density, which is delivered to the powder material. The stainless steel samples were divided into 12 groups, depends of the energy density. The titanium parts were printed at the same value of energy, and the process parameters are changed. The microscope observation and relative density measurements were carried out. Based on the obtained results, it can be confuted that the SLM parameters have a significant effect on the samples properties and the mechanism formed defect in both material are similar.

scholarly journals Microstructural and Mechanical Response of NiTi Lattice 3D Structure Produced by Selective Laser Melting

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 814 ◽  
Author(s):  
Carlo Alberto Biffi ◽  
Paola Bassani ◽  
Jacopo Fiocchi ◽  
Ausonio Tuissi
Keyword(s):  
Martensitic Transformation ◽  
Selective Laser Melting ◽  
Mechanical Response ◽  
Electron Backscatter Diffraction ◽  
Bulk Material ◽  
Niti Alloy ◽  
3D Structure ◽  
Lattice Structures ◽  
Laser Melting ◽  
Scanning Calorimetry

Nowadays, additive manufacturing (AM) permits to realize complex metallic structural parts, and the use of NiTi alloy, known as Nitinol, allows the integration of specific functions to the AM products. One of the most promising designs for AM is concerning the use of lattice structures that show lightweight, higher than bulk material deformability, improved damping properties, high exchange surface. Moreover, lattice structures can be realized with struts, having dimensions below 1 mm—this is very attractive for the realization of Nitinol components for biomedical devices. In this light, the present work regarded the experimental characterization of lattice structures, produced by selective laser melting (SLM), by using Ni-rich NiTi alloy. Differential scanning calorimetry (DSC), electron backscatter diffraction (EBSD), and compression testing were carried out for analyzing microstructure, martensitic transformation (MT) evolution, and superelasticity response of the SLMed lattice samples. The lattice microstructures were compared with those of the SLMed bulk material for highlighting differences. Localized martensite was detected in the nodes zones, where the rapid solidification tends to accumulate solidification stresses. An increase of martensitic transformation temperatures was also observed in lattice NiTi.

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