Influence Of Selective Laser Melting Process Parameters Research Articles

Study on forming process and performance of nano-La2O3 reinforced tungsten-based composites by selective laser melting

In this study, La2O3 nanoparticles were incorporated into a tungsten (W) matrix to enhance the microstructure and properties of pure W. The selective laser melting (SLM) process for W-2wt% La2O3 was optimized, and the influence of SLM processing parameters on the relative density and internal defects of the samples was examined. Challenges such as uneven powder layering and layer-by-layer thickening during the SLM process were addressed by incorporating a homogeneous material support formed with low laser energy density beneath the sample. This approach widened the process window for sample formation, resulting in a 2.38 % increase in the average relative density of supported samples compared to unsupported ones.With optimized parameters of 240W laser power, 200 mm/s scanning speed, and 80 μm hatch spacing, the sample achieved a relative density of 98.32 % with minimal internal pores, though some microcracks remained. Further investigation revealed that surface roughness decreased with increasing laser power and scanning speed. High laser power combined with low scanning speed yielded good surface quality. Under conditions of high relative density (over 96 %), samples processed with low laser power and high scanning speed (200W, 200 mm/s) exhibited fine and uniform grain morphology, few internal defects, and excellent mechanical properties, with a microhardness of 474HV and a compressive strength of 2237 MPa.

Phase Composition, Microstructure and Mechanical Properties of Zr57Cu15Ni10Nb5 Alloy Obtained by Selective Laser Melting

Zr57Cu15Ni10Nb5 (more known as Vit-106) is a promising zirconium-based alloy with a high glass-forming ability, and belongs to the so-called bulk metallic glasses (BMG). Workpieces with a size of around one centimeter in all three dimensions can be obtained from a BMG alloy by casting. However, further increasing the cast size decreases the cooling rate and thus induces crystallization. Selective laser melting (SLM) is a well-known technique to overcome size limitations for BMGs because a workpiece is built by the addition of multiple melt portions in which the cooling rate is kept above the critical one. Currently, BMG parts obtained by SLM suffer from partial crystallization. The present work studies the influence of SLM process parameters on the partial crystallization of Vit-106 by metallography and the influence of the microstructure on mechanical properties by microhardness and wear resistance testing. Submicron crystalline inclusions are observed in an amorphous matrix of a Vit-106 alloy obtained by SLM. The size and the concentration of the inclusions can be controlled by varying the laser scanning speed. It is shown that submicron crystalline inclusions formed in the amorphous matrix during SLM can favorably affect microhardness and wear resistance.

Pure tantalum manufactured by laser powder bed fusion: Influence of scanning speed on the evolution of microstructure and mechanical properties

To improve the performance of pure tantalum manufactured by selective laser melting (SLM) and meet its application requirements in medicine and industry, this paper studied the influence of SLM process parameters on the as-built surface morphology and mechanical performance, and successfully obtained a sample with a relative density of over 99%, ultimate tensile strength of 706Mpa and fracture elongation over 32%. It's found that the scanning speed has a significant influence on the microstructure. Moreover, the fractured morphology shows that it is easy to cause cracks at the lower energy density. However, at a higher energy density, it is easy to induce defects such as keyhole induced pores. The appropriate process parameters of additive manufacturing matching the pure tantalum with higher relative density and better mechanical properties have precious value for its application in medicine and industry.

Improving the quality of AISI H13 tool steel produced by selective laser melting

AISI H13 tool steel is intended for making various tools and die-casting molds, which generally are of complex shapes. The application of selective laser melting (SLM) can significantly speed up their production, but it is accompanied by the appearance of various defects, such as high surface roughness, cracking, and reduced density. In particular, there is a fairly limited amount of data on the influence of SLM process parameters on the surface roughness of tool steels. The aim of this work is to study the possibility of improving the quality of AISI H13 steel by varying laser power and scanning speed during SLM. Optical profilometry and microscopy are used as methods of investigation, with statistical data analysis being carried out. It has been discovered that both surface roughness and porosity can be effectively influenced by varying the laser power and scanning speed during SLM. A direct relationship between surface roughness and porosity has been established, and this makes it possible to control effectively the quality of AISI H13 tool steel produced by selective laser melting. Steel of the highest quality with the lowest surface roughness and porosity has been obtained at a laser power of 250 W and a scanning speed of 350 mm/s. It has also been found that varying laser power and scanning speed does not prevent crack formation, and other technological solutions should be sought to eliminate cracking.

Process optimization and mechanical properties of oxide dispersion strengthened nickel-based superalloy by selective laser melting

Oxide dispersion strengthened nickel-based superalloy (ODSN) is widely used in structural materials such as aerospace and nuclear industry, but its uniform dispersion distribution of particles makes it only necessary to manufacture using conventional powder metallurgy technique. Selective laser melting (SLM) is first selected as a novel method for manufacturing ODSN. The influence of SLM process parameters (laser power, scanning speed, hatch spacing) on the microstructure and mechanical property in ODSN has been investigated, using Taguchi method (TM) and Response surface methodology (RSM). Orthogonal array and Box-Behnken design were utilized to design the experiments. Analysis of variance, signal-to-noise ratio, main influence diagrams, 3D response surface, and the corresponding contour plots were measured to evaluate the effects of factors on the tensile strength. By comparing the results of the experiment showed that optimum parametric combination from TM and RSM induced better tensile strength. The optimum process parameters were predicted, validated, and subsequently employed to build samples to assess mechanical properties during 25–1000 °C. The samples produced using SLM showed approximate tensile strength, compared to hot extruded ODSN of similar composition. Fracture morphology results good agreement with mechanical property at room and elevated temperature.

The Influence of Selective Laser Melting Process Parameters on the Property of TiAlN/TiN Multilayer Coating on the 316L Steel

Selective laser melting (SLM) is an important advanced additive manufacturing technology. The existing SLM products cannot fully meet the requirements of high-precision and strength of the mechanical component because of their defects. The TiAlN/TiN multilayer coating can improve the surface property of SLM products. The present work aims to explore the influences of different process parameters of SLM on the property of TiAlN/TiN multilayer coating plating on the 361L specimen and the mechanism of these influences. Taking laser power, scanning speed, and scanning space as factors, an orthogonal experiment was designed. The TiAlN/TiN multilayer coating specimens can be obtained by plating on the 361L specimen, fabricated by the process parameters of SLM on the orthogonal experiment. The surface topographies and properties of TiAlN/TiN multilayer coating were tested, the influences of SLM process parameters on TiAlN/TiN multilayer coating were analyzed, and the optimal process parameter was obtained. The electron microscope images revealed that the surface morphology of TiAlN/TiN multilayer coating plating on the SLM specimen was relatively flat, and there were some macro-particles in different sizes and pin holes dispersed on it. The thickness of the TiAlN/TiN multilayer coating was 2.77–3.29 μm. The microhardness value of coating SLM specimen was more than four times that of the uncoated SLM specimen and the wear rates of the uncoated specimen were 2–4 times that of the corresponding coating specimen. The comprehensive analysis shows that the laser power had the greatest influence on the comprehensive property of the coating. The primary cause of the influence of SLM process parameters on the properties of the TiAlN/TiN multilayer coating was preliminarily discussed. When the laser power was 170 W, the scanning speed was 1,100 mm/s, and the scanning space was 0.08mm, the TiAlN/TiN multilayer coating plating on the SLM specimen had the best comprehensive property.

Single Track Formation during Selective Laser Melting of Ti-6Al-4V Alloy

Selective laser melting (SLM) is an additive manufacturing technology that allows to produce functional parts with extremely complex shape from metal powder feedstock. 240 single tracks with the length of 10 mm were fabricated using different SLM process parameters: laser power output, powder layer thickness, point distance and exposure time. Obtained single tracks were measured using optical microscopy. An influence of SLM process parameters on geometrical characteristics of obtained single tracks was investigated.

The Effect of Selective Laser Melting Process Parameters on the Microstructure and Mechanical Properties of Al6061 and AlSi10Mg Alloys.

Additive manufacturing (AM) offers customization of the microstructures and mechanical properties of fabricated components according to the material selected and process parameters applied. Selective laser melting (SLM) is a commonly-used technique for processing high strength aluminum alloys. The selection of SLM process parameters could control the microstructure of parts and their mechanical properties. However, the process parameters limit and defects obtained inside the as-built parts present obstacles to customized part production. This study investigates the influence of SLM process parameters on the quality of as-built Al6061 and AlSi10Mg parts according to the mutual connection between the microstructure characteristics and mechanical properties. The microstructure of both materials was characterized for different parts processed over a wide range of SLM process parameters. The optimized SLM parameters were investigated to eliminate internal microstructure defects. The behavior of the mechanical properties of parts was presented through regression models generated from the design of experiment (DOE) analysis for the results of hardness, ultimate tensile strength, and yield strength. A comparison between the results obtained and those reported in the literature is presented to illustrate the influence of process parameters, build environment, and powder characteristics on the quality of parts produced. The results obtained from this study could help to customize the part’s quality by satisfying their design requirements in addition to reducing as-built defects which, in turn, would reduce the amount of the post-processing needed.

Influence of Selective Laser Melting Process Parameters on Porosity of TiAl6V4 Alloy Fabricated by 200W CO<sub>2</sub> Laser

In this research TiAl6V4 titanium base alloy was used for Selective Laser Melting (SLM). This alloy is widely used in aerospace and medical industries. To determine the influence of SLM process parameters on TiAl6V4 10x10x5 mm specimens were fabricated using different SLM process parameters. The porosity of fabricated specimens was determined by microscopy analysis of cross-sections and by the Archimedes method.

Влияние параметров селективного лазерного сплавления на пористость образцов из сплава TiAl6V4

In this research TiAl6V4 titanium base alloy was used for Selective Laser Melting (SLM). This alloy is widely used in aerospace and medical industries. For determination of influence of SLM process parameters on TiAl6V4 10x10x5 mm specimens were fabricated by using different SLM process parameters. The porosity of fabricated specimens was determined by microscopy analysis of cross-sections. The lowest porosity that was achieved is about of 0.5%.

Microstructure evolution and mechanical properties of Al-Al2O3 composites fabricated by selective laser melting

The promising selective laser melting (SLM) technology was introduced to prepare Al based composites reinforced by Al2O3 particles. The influence of SLM processing parameters on the densification behavior, microstructure, microhardness and resultant wear performance was studied in detail. The results revealed that the near fully dense composite part (97.3% theoretical density) was achieved with the optimized v of 550mm/s applied. A proper decrease in the applied v to 550mm/s was proved feasible to favor the Al2O3 particle dispersion homogeneity due to the trapping effect of Al2O3 particle with the advancing interface in the molten pool. Besides, a continuous and compatible interface was developed in this case. At an even lower v of 450mm/s, the homogeneously dispersed Al2O3 reinforcements exhibited a novel ring structures along the boundaries of molten pool, but showing a significant coarsening morphology. The optimally prepared fully dense Al-Al2O3 composite part exhibited excellent hardness with a mean value of 175HV0.1 and superior wear performance with a considerably low coefficient of friction of 0.11 and a significantly reduced wear rate of 4.75×10−5mm3N−1m−1.

Selective Laser Melting Additive Manufacturing of Hard-to-Process Tungsten-Based Alloy Parts With Novel Crystalline Growth Morphology and Enhanced Performance

Selective laser melting (SLM) additive manufacturing (AM) of hard-to-process W-based parts with the addition of 2.5 wt.% TiC was performed using a new metallurgical processing mechanism with the complete melting of the high-melting-point powder. The influence of SLM processing parameters, especially laser scan speed and attendant laser fluence (LF), on densification behavior, microstructural development, and hardness/wear performance of SLM-processed W-based alloy parts was disclosed. The densification response of SLM-processed W-based parts decreased both at a low LF of 10.7 J/mm2, caused by the limited SLM working temperature and wetting characteristics of the melt, and at an excessively high LF of 64 J/mm2, caused by the significant melt instability and resultant balling effect and microcracks formation. The laser-induced complete melting/solidification mechanism contributed to the solid solution alloying of Ti and C in W matrix and the development of unique microstructures of SLM-processed W-based alloy parts. As the applied LF increased by lowering laser scan speed, the morphologies of W-based crystals in SLM-processed alloy parts experienced a successive change from the cellular crystal to the cellular dendritic crystal and, finally, to the equiaxed dendritic crystal, due to an elevated constitutional undercooling and a decreased thermal undercooling. The optimally prepared W-based alloy parts by SLM had a nearly full densification rate of 97.8% theoretical density (TD), a considerably high microhardness of 809.9 HV0.3, and a superior wear/tribological performance with a decreased coefficient of friction (COF) of 0.41 and a low wear rate of 5.73 × 10−7 m3/(N m), due to the combined effects of the sufficiently high densification and novel crystal microstructures of SLM-processed W-based alloy parts.

Influence of SLM Process Parameters on Porosity of Nickel Base Heat Resistance Alloy EP648

In this research EP648 nickel base heat resistance alloy was used for Selective Laser Melting (SLM). This alloy can be used for producing details at high mechanical and thermal load by SLM for aerospace, automotive, shipbuilding and energy industries. To define the influence of SLM process parameters on EP648 4x4x4 mm cubic specimens were fabricated with different process parameters (scanning speed, laser power, layer thickness). The porosity of fabricated specimens was determined by scanning electron microscopy of polished cross-sections.

The development of TiNi-based negative Poisson's ratio structure using selective laser melting

There is a growing interest in using additive manufacturing to produce smart structures, which have the capability to respond to thermal and mechanical stimuli. In this report, Selective Laser Melting (SLM) is used to build a Negative Poisson's Ratio (NPR) TiNi-based Shape Memory Alloy (SMA) structure, creating a multi-functional structure that could be used as reusable armour. The study assesses the influence of SLM process parameters (laser power, scan speed, and track spacing) on the microstructural and structural integrity development in a Ti-rich TiNi alloy, as well as the impact of the post-process homogenisation treatment on the microstructure and phase transformations. The builds generally shows stress-induced cracks and residual porosity, which could be minimised through process optimisation. Nonetheless, the homogenisation treatment is essential to reduce the fraction of Ti2Ni intermetallics, which are known to disturb the B19′-chemistry, and hence the required phase transformation temperatures. The optimum process parameters are finally used to fabricate NPR structures, which were mechanically tested to validate the Poisson's ratio predictions. A higher ductility was observed in the structures that have undergone the homogenisation treatment.