Selective laser melting (SLM) of AISI 316L—impact of laser power, layer thickness, and hatch spacing on roughness, density, and microhardness at constant input energy density

In this paper the effect of selective laser melting (SLM) input energy density on densification behavior and tensile strengths of commercially pure (CP) titanium was investigated. Fully dense and high strength SLM CP titanium has been obtained. A complex bone-compatible tetrakaidecahedron based porous structure has been successfully SLM-fabricated with optimized laser parameters.

Download Full-text

Influence of Selective Laser Melting Process Parameters on Densification Behavior, Surface Quality and Hardness of 18Ni300 Steel

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.861.77 ◽

2020 ◽

Vol 861 ◽

pp. 77-82

Author(s):

Gan Li ◽

Cheng Guo ◽

Wen Feng Guo ◽

Hong Xing Lu ◽

Lin Ju Wen ◽

...

Keyword(s):

Energy Density ◽

Relative Density ◽

Maraging Steel ◽

Surface Quality ◽

Selective Laser Melting ◽

Process Parameters ◽

Laser Power ◽

Densification Behavior ◽

Laser Melting ◽

Scan Speed

This study investigated the effect of laser power (P), scan speed (v) and hatch space (h) on densification behavior, surface quality and hardness of 18Ni300 maraging steel fabricated by selective laser melting (SLM). The results indicated that the relative density of the SLMed samples has a shape increase from 73% to 97% with the laser energy density increasing from 0.5 to 2.2 J/mm2. The relative density ≥ 99% was achieved at the energy density in the range of 2.2~5.9 J/mm2. The optimum process parameters were found to be laser power of 150~200 W, scan speed of 600mm/s and hatch space of 0.105mm. In addition, it was found that the hardness increased initially with the increasing relative density up to relative density of 90% and then little relationship, but finally increase again significantly. This work provides reference for determining process parameters for SLMed maraging steel and the development of 3D printing of die steels.

Download Full-text

Effects of the Processing Parameters on the Forming Quality of Stainless Steel Parts by Selective Laser Melting

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.189-193.3668 ◽

2011 ◽

Vol 189-193 ◽

pp. 3668-3671 ◽

Cited By ~ 5

Author(s):

Qing Song Wei ◽

Xiao Zhao ◽

Li Wang ◽

Rui Di Li ◽

Jie Liu ◽

...

Keyword(s):

Layer Thickness ◽

Selective Laser Melting ◽

Molten Pool ◽

Laser Power ◽

Single Layer ◽

Scanning Speed ◽

Processing Parameters ◽

Powder Layer ◽

Laser Melting

Selective Laser Melting (SLM) can produce high-performance metal parts with complex structures. However, it’s difficult to control the processing parameters, because many factors involves. From the perspective of the molten pool, the study focuses on the effects of processing parameters, including scanning speed, laser power, scanning space, layer thickness, and scanning strategies, on the surface quality, the balling effect, the density of SLM parts, by conducting experiments of single track, single layer and block forming. The results show that the quality of the molten pool is affected by laser power and scanning speed. Scanning drove in the strategy of “jumping and turning”，a smooth surface and a less balling effect will be obtained. The thicker the powder layer is, the lower density will be obtained. The optimal parameters from series of experiments are: laser power of 98W; scanning speed of 90mm/s; scanning space of 0.07mm; layer thickness of 0.1mm; and scanning strategy of “jumping and turning”.

Download Full-text

Experimental Investigation into the Single-Track of Selective Laser Melting of IN625

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.233-235.2844 ◽

2011 ◽

Vol 233-235 ◽

pp. 2844-2848 ◽

Cited By ~ 11

Author(s):

Li Wang ◽

Qing Song Wei ◽

Yu Sheng Shi ◽

Jin Hui Liu ◽

Wen Ting He

Keyword(s):

Energy Density ◽

Relative Density ◽

Surface Quality ◽

Selective Laser Melting ◽

Laser Power ◽

Laser Energy ◽

Scanning Speed ◽

Single Track ◽

Laser Melting ◽

Metallic Parts

Selective laser melting(SLM) is driven by the need to fabricate functional metallic parts and tools with near shape and density. The method of process to fabricate a metal part will save materials, time and energy compared to the traditional manufacturing methods. Unlike the selective laser sintering (SLS), the metal powder particles are molten by the laser beam during the process of selective laser melting. In this paper, IN625 powders were adopted to investigate the characters of single molten track. The factors that affect the surface quality and relative density are the process parameters such as the laser energy, scan speed and so on. They were studied to find out the correlation between the parameters and formation of single-track. It has been found that Optimal ratio between laser power and scanning speed (P/v) is 1-1.5 for IN625 SLM. P/v is the linear energy density. It also has been found that the width and height of single-track can be calculated when the linear energy density is given. In this study the laser power, scan spacing and the hatch spacing which affect the surface quality and the relative density of the metallic parts were optimized.

Download Full-text

Effect of Layer Thickness in Selective Laser Melting on Microstructure of Al/5 wt.%Fe2O3Powder Consolidated Parts

The Scientific World JOURNAL ◽

10.1155/2014/106129 ◽

2014 ◽

Vol 2014 ◽

pp. 1-10 ◽

Cited By ~ 18

Author(s):

Sasan Dadbakhsh ◽

Liang Hao

Keyword(s):

Layer Thickness ◽

Selective Laser Melting ◽

Laser Power ◽

Fine Particles ◽

Lower Layer ◽

Scanning Speed ◽

Laser Melting ◽

The Matrix ◽

Fe Intermetallics

In situreaction was activated in the powder mixture of Al/5 wt.%Fe2O3by using selective laser melting (SLM) to directly fabricate aluminium metal matrix composite parts. The microstructural characteristics of thesein situconsolidated parts through SLM were investigated under the influence of thick powder bed, 75 μm layer thickness, and 50 μm layer thickness in various laser powers and scanning speeds. It was found that the layer thickness has a strong influence on microstructural outcome, mainly attributed to its impact on oxygen content of the matrix. Various microstructural features (such as granular, coralline-like, and particulate appearance) were observed depending on the layer thickness, laser power, and scanning speed. This was associated with various material combinations such as pure Al, Al-Fe intermetallics, and Al(-Fe) oxide phases formed afterin situreaction and laser rapid solidification. Uniformly distributed very fine particles could be consolidated in net-shape Al composite parts by using lower layer thickness, higher laser power, and lower scanning speed. The findings contribute to the new development of advanced net-shape manufacture of Al composites by combining SLM andin situreaction process.

Download Full-text

Densification behavior of 316L-NiB stainless steel powder and surface morphology during selective laser melting process using pulsed Nd:YAG laser

Rapid Prototyping Journal ◽

10.1108/rpj-07-2017-0136 ◽

2019 ◽

Vol 25 (1) ◽

pp. 47-54 ◽

Cited By ~ 3

Author(s):

Jelena Stašić ◽

Dušan Božić

Keyword(s):

Stainless Steel ◽

Layer Thickness ◽

Selective Laser Melting ◽

Laser Power ◽

Average Power ◽

Favorable Effect ◽

Powder Layer ◽

Laser Melting ◽

Content Type ◽

Hcl Solution

Purpose This paper aims to report the production of 316L-1 Wt.% NiB cubes by using the selective laser melting (SLM) process. The laser used was pulsed, millisecond Nd:YAG system with maximum average power 100 W. Design/methodology/approach Densification under different processing conditions (pulse energy, average laser power, laser scan speed, powder layer thickness, pulse frequency) was investigated. Morphology, macro and microstructure of laser melted samples were characterized by digital camera images and by scanning electron microscope. Density of the cubes was determined by Archimedes method in water. Vickers microhardness of samples was determined under the load of 25 g. Corrosion behavior of 316L and 316L-NiB samples was conducted in 5 per cent HCl solution at the testing temperature of 20°C during 240 h. Findings Using laser power of ∼60-70 W, lower beam overlap and powder layer thickness of 200 µm, 3D cubical samples were obtained with significant balling in individual layers and an overall porosity being around 30 per cent. By increasing laser power to ∼80 W, with higher beam overlap and lower powder layer thickness of 100 µm, SLM parts with no balling and the presence of small pores of up to 4 per cent (20 Hz) and 9 per cent (40 Hz) were obtained. With further increase of laser power to 90 W, overall porosity rose to around 12 per cent. The addition of 1 Wt.% NiB to stainless steel negligibly lowered its corrosion resistance in 5 per cent HCl solution. Originality/value A part from 316L stainless steel with balling-free structure and good density was successfully obtained through pulsed-SLM process with the aid of 1 Wt.% of NiB addition. Aside from significant influence on the improved structure of cubes, NiB had a favorable effect on microhardness values while practically not affecting the corrosion resistivity of the base material in an aggressive surrounding.

Download Full-text

Determinants of the surface quality, density and dimensional correctness in selective laser melting of the Ti-13Zr-13Nb alloy

Matériaux & Techniques ◽

10.1051/mattech/2018050 ◽

2018 ◽

Vol 106 (4) ◽

pp. 405

Author(s):

Tomasz Seramak ◽

Katarzyna Zasinska ◽

Michel Mesnard ◽

Karolina Bednarz ◽

Paulina Fic ◽

...

Keyword(s):

Energy Density ◽

Relative Density ◽

Surface Quality ◽

Selective Laser Melting ◽

Laser Power ◽

Thermal Stresses ◽

Laser Melting ◽

Dimensional Precision ◽

Scan Time

Selective laser melting is widely used for custom-designed elements. Successful manufacturing depends on laser treatment parameters and material features. This research aimed to determine the effects of laser power, scan time and hatch distance on surface quality, relative density and dimensional precision for cuboids made of the Ti-13Zr-13Nb alloy. The influence of energy density, energy flux and pre-heating was seen to be decisive to different degrees for the quality of the final specimen. The results obtained were used to produce prosthetic crowns and bridges. The thermal stresses that appeared resulted in a deflection of the bridges and consequently in a change in design approach.

Download Full-text

Selective Laser Melting of Mechanically Alloyed Metastable Al5Fe2 Powders

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4043730 ◽

2019 ◽

Vol 141 (7) ◽

Cited By ~ 1

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.

Download Full-text