Performance of High Layer Thickness in Selective Laser Melting of Ti6Al4V

Shi, Xuezhi; Ma, Shuo; Liu, Changmeng; Cheng, Chaohua; Wu, Qingyun; Chen, Xianping; Lu, Jiping

doi:10.3390/ma9120975

Cited by 112 publications

(47 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…As long as the laser power is great enough and the travel speed is not excessive, this keyhole will remain open. Process parameter combinations which lead to higher energy per unit length values and, thus, higher weld pool penetration, apart from being energy costly and/or slow, are prone to higher sensitivity to porosity [29]. In order to achieve process feasibility in SLM, keyhole effects in melt pools are to be avoided, so that overlap with underlying layers and adjacent scan vectors during processing can be attained without failures.…”

Section: Application Of the Model To An Slm Processmentioning

confidence: 99%

Phase Change with Density Variation and Cylindrical Symmetry: Application to Selective Laser Melting

Fyrillas

Ioannou

Papadakis

et al. 2019

JMMP

View full text Add to dashboard Cite

In this paper we introduce an analytical approach for predicting the melting radius during powder melting in selective laser melting (SLM) with minimum computation duration. The purpose of this work is to evaluate the suggested analytical expression in determining the melt pool geometry for SLM processes, by considering heat transfer and phase change effects with density variation and cylindrical symmetry. This allows for rendering first findings of the melt pool numerical prediction during SLM using a quasi-real-time calculation, which will contribute significantly in the process design and control, especially when applying novel powders. We consider the heat transfer problem associated with a heat source of power Q' (W/m) per unit length, activated along the span of a semi-infinite fusible material. As soon as the line heat source is activated, melting commences along the line of the heat source and propagates cylindrically outwards. The temperature field is also cylindrically symmetric. At small times (i.e., neglecting gravity and Marangoni effects), when the density of the solid material is less than that of the molten material (i.e., in the case of metallic powders), an annulus is created of which the outer interface separates the molten material from the solid. In this work we include the effect of convection on the melting process, which is shown to be relatively important. We also justify that the assumption of constant but different properties between the two material phases (liquid and solid) does not introduce significant errors in the calculations. A more important result; however, is that, if we assume constant energy input per unit length, there is an optimum power of the heat source that would result to a maximum amount of molten material when the heat source is deactivated. The model described above can be suitably applied in the case of selective laser melting (SLM) when one considers the heat energy transferred to the metallic powder bed during scanning. Using a characteristic time and length for the process, we can model the energy transfer by the laser as a heat source per unit length. The model was applied in a set of five experimental data, and it was demonstrated that it has the potential to quantitatively describe the SLM process.

show abstract

Section: Application Of the Model To An Slm Processmentioning

confidence: 99%

Phase Change with Density Variation and Cylindrical Symmetry: Application to Selective Laser Melting

Fyrillas

Ioannou

Papadakis

et al. 2019

JMMP

View full text Add to dashboard Cite

show abstract

“…Several works were done in order to increase building rate by several times and to reduce costs by using higher layer thickness and coarser metal powders [10][11][12]. However, the increase of the layer thickness leads to the deterioration of the surface quality in the conditions in which anyway the roughness of SLM top surfaces is strongly different from the roughness of side surfaces [13].…”

Section: Introductionmentioning

confidence: 99%

Edge and corner effects in selective laser melting of IN 625 alloy

Matache¹,

Vladut²,

Paraschiv³

et al. 2020

Manufacturing Rev.

View full text Add to dashboard Cite

Experimental investigations on top surface of prismatic specimens, manufactured by Selective Laser Melting of IN 625 alloy, were carried out in order to assess the influence of laser power and scanning speed on edge and corner effects. Since the melt-pool behaviour is strongly influenced by the process parameters, all specimens were manufactured with no contour using the same layer thickness, hatch distance and scanning strategy at different levels of laser powers and scanning speeds. 3D laser surface scanning was performed in order to measure surface changes. The experimental results have revealed that melt-pool behaviour during solidification generates elevated ridges on both specimen sides and corners that are strongly influenced by the energy input. The edge ridges width increases with increasing the laser power and decrease with increasing the scanning speed, the rising of corners being much more pronounced. On the contrary, at constant laser power and variable scanning speeds the edge and corner ridges decrease.

show abstract

“…For example, Ma et al found that by increasing the layer thickness from 60 µm to 150 µm using 1Cr18Ni9Ti stainless steel (SS), the building rate can be increased, and the relative densities ranged from 99.3-99.8% [7]. Shi et al used Ti6Al4V to investigate the performance of a higher layer thickness and found that the building rate can be improved by up to 7.2 mm 3 /s [8]. Wang et al investigated AISI grade 316 SS powder using a layer thickness of 150 µm, and obtained a higher building rate and relative density of 12 mm 3 /s and 99.9%, respectively [9].…”

Section: Introductionmentioning

confidence: 99%

Characterization of 17-4PH Single Tracks Produced at Different Parametric Conditions towards Increased Productivity of LPBF Systems—The Effect of Laser Power and Spot Size Upscaling

Makoana

Yadroitsava

Möller

et al. 2018

Metals

View full text Add to dashboard Cite

Global industrial adoption of laser-based powder bed fusion (LPBF) technology is still limited by the production speed, the size of the build envelope, and therefore the maximum part size that can be produced. The cost of LPBF can be driven down further by improving the build rates without compromising structural integrity. A common approach is that the build rate can be improved by increasing the laser power and beam diameter to instantly melt a large area of powder, thus reducing the scanning time for each layer. The aim of this study was to investigate the aspects of upscaling LPBF processing parameters on the characteristic formation of stable single tracks, which are the primary building blocks for this technology. Two LPBF systems operating independently, using different parameter regimes, were used to produce the single tracks on a solid substrate deposited with a thin powder layer. The results obtained indicate that higher laser power and spot size can be used to produce stable tracks while the linear energy input is increased. It was also shown statistically that the geometrical characteristics of single tracks are mainly affected by the laser power and scanning speed during the scanning of a thin powder layer.

show abstract

Performance of High Layer Thickness in Selective Laser Melting of Ti6Al4V

Cited by 112 publications

References 34 publications

Phase Change with Density Variation and Cylindrical Symmetry: Application to Selective Laser Melting

Phase Change with Density Variation and Cylindrical Symmetry: Application to Selective Laser Melting

Edge and corner effects in selective laser melting of IN 625 alloy

Characterization of 17-4PH Single Tracks Produced at Different Parametric Conditions towards Increased Productivity of LPBF Systems—The Effect of Laser Power and Spot Size Upscaling

Contact Info

Product

Resources

About