Single scan vector prediction in selective laser melting

Wits, Wessel W.; Bruins, Rutger; Terpstra, Lennard; Huls, R.A.; Geijselaers, H.J.M.

doi:10.1016/j.addma.2015.12.001

Cited by 19 publications

(14 citation statements)

References 12 publications

(13 reference statements)

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“…In Fig. 7, melt-pool width w is plotted against energy density P/v for selected values of P. It is found that the melt pool width, predicted with the material properties listed in Table. 1 yields the best agreement with the experimental measurements of Wits et al [42]. The thermal material properties tabulated in Table 1 correspond to a temperature value of 2500 K [44] which is above the melting point.…”

Section: Laser Scanning On a Semi-infinite Platesupporting

confidence: 75%

“…In this section, we analyse the temperature-time evolution due to a single laser scan vector applied on a semi-infinite solid and compare our predictions with relevant experimental findings reported in [42]. Since in our formulation, a laser scan vector is represented with a number of point sources which is controlled by the time step ∆t we shall determine:…”

Section: Validationmentioning

confidence: 99%

“…Wits et al [42] built single lines of Ti-6Al-4V alloy with SLM on a large base plate of the same alloy. The dimensions of the base plate were length L l =30 mm, width L w =30 mm and depth L d =5 mm, while laser scan vectors of 6.5 mm with laser spot radius of 35 µm were applied on a powder layer with a thickness of 50 µm.…”

Section: Laser Scanning On a Semi-infinite Platementioning

confidence: 99%

“…14is based on the linear heat equation and requires the material parameters ρ, c p and k to be temperature independent whereas, in reality, heat capacity c p and the conductivity k have a significant temperature dependence. Therefore the thermal material properties in our model are determined upon comparing model predictions with the experimental measurements and FE predictions of Wits et al [42]. In Fig.…”

Section: Laser Scanning On a Semi-infinite Platementioning

confidence: 99%

“…As mentioned, these effects have been neglected in our model. Moreover, phase transitions -especially evaporation -are also expected to play a more important role at high power and energy densities [42]…”

Section: Laser Scanning On a Semi-infinite Platementioning

confidence: 99%

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A semi-analytical thermal modelling approach for selective laser melting

Yang

Knol

Keulen

et al. 2018

Additive Manufacturing

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Selective laser melting (SLM) wherein a metal part is built in a layer-by-layer manner in a powder bed is a promising and versatile way for manufacturing components with complex geometry. However, components built by SLM suffer from substantial deformation of the part and residual stresses. Residual stresses arise due to temperature gradients inherent to the process and the accompanying deformation. It is well known that the SLM process parameters and the laser scanning strategy have a substantial effect on the temperature transients of the part and henceforth on the degree of deformations and residual stresses. In order to provide a tool to investigate this relation, a semi-analytical thermal model of the SLM process is presented which determines the temperature evolution in a 3D part by way of representing the moving laser spot with a finite number of point heat sources. The solution of the thermal problem is constructed from the superposition of analytical solutions for point sources which are known in semi-infinite space and complimentary numerical/analytical fields to impose the boundary conditions. The unique property of the formulation is that numerical discretisation of the problem domain is decoupled from the steep gradients in the temperature field associated with localised laser heat input. This enables accurate and numerically tractable simulation of the process. The predictions of this semi-analytical model are validated by experiments and the exact solution known for a simple thermal problem. Simulations for building a complete layer using two different scanning patterns and subsequently building of multiple layers with constant and rotating scanning patterns in successive layers are performed. The computational efficiency of the semi-analytical tool is assessed which demonstrates its potential to gain physical insight in the full SLM process with acceptable computational costs.

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Section: Laser Scanning On a Semi-infinite Platesupporting

confidence: 75%

Section: Validationmentioning

confidence: 99%

Section: Laser Scanning On a Semi-infinite Platementioning

confidence: 99%

Section: Laser Scanning On a Semi-infinite Platementioning

confidence: 99%

Section: Laser Scanning On a Semi-infinite Platementioning

confidence: 99%

See 3 more Smart Citations

A semi-analytical thermal modelling approach for selective laser melting

Yang

Knol

Keulen

et al. 2018

Additive Manufacturing

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A pragmatic continuum level model for the prediction of the onset of keyholing in laser powder bed fusion

Philo

Mehraban

Holmes

et al. 2018

Int J Adv Manuf Technol

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Laser powder bed fusion (L-PBF) is a complex process involving a range of multi-scale and multi-physical phenomena. There has been much research involved in creating numerical models of this process using both high and low fidelity modelling approaches where various approximations are made. Generally, to model single lines within the process to predict melt pool geometry and mode, high fidelity computationally intensive models are used which, for industrial purposes, may not be suitable. The model proposed in this work uses a pragmatic continuum level methodology with an ablation limiting approach at the mesoscale coupled with measured thermophysical properties. This model is compared with single line experiments over a range of input parameters using a modulated yttrium fibre laser with varying power and line speeds for a fixed powder layer thickness. A good trend is found between the predicted and measured width and depth of the tracks for 316L stainless steel where the transition into keyhole mode welds was predicted within 13% of experiments. The work presented highlights that pragmatic reduced physics-based modelling can accurately capture weld geometry which could be applied to more practical based uses in the L-PBF process. Keywords Additive manufacturing • Laser powder bed fusion • Modelling • Keyhole-mode laser melting • 316L stainless steel Nomenclature ρ Density C p Specific heat capacity T Temperature κ Thermal conductivity α Thermal diffusivity t Timê n Unit normal to surface q v Volumetric energy input q Irradiated heat flux

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