The effect of scanning strategies on electron beam sintering

Zaeh, Michael F.; Kahnert, Markus

doi:10.1007/s11740-009-0157-1

Cited by 29 publications

(10 citation statements)

References 8 publications

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“…Nevertheless, there are only few publications on bulk material, although they attract more and more interest. Thus, Zaeh and Kahnert reported the effects of scanning strategies for the building of compact parts. Other works focus on the microstructure or the crystallographic variant selection contained by rapid solidification during the build of compact parts.…”

Section: Introductionmentioning

confidence: 99%

Influence of the Scanning Strategy on the Microstructure and Mechanical Properties in Selective Electron Beam Melting of Ti–6Al–4V

Scharowsky¹,

Juechter²,

Singer³

et al. 2015

Adv Eng Mater

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Selective electron beam melting (SEBM) is perhaps the fastest production process for additive manufacturing techniques from powder beds. In the present investigation, scan speeds of 10 m s À1 have been used successfully for the melting. Nevertheless, the beam power has to be adjusted to guarantee a density of more than 99.5% for the build samples. The aim of this paper is to investigate the effect of the scan speed and beam power on the microstructure and the mechanical properties of Ti-6Al-4V. Therefore, a process map with a window for samples with a density higher than 99.5% and a good geometrical accuracy was developed. But, there are strong differences in microstructure and the resulting mechanical properties. These differences result from changes in the total energy input. In the presented work, strength is found to increase somewhat with decreasing volume energy (60-30 J mm À3 ) at a scan speed of 4 m s À1 as the cooling rate increases. This causes a change in microstructure, as the a platelet size varies in the range between 400 nm and 1.3 mm. Thus, an increase in ultimate tensile strength of 5% could be realized by adjusted energy input.

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Section: Introductionmentioning

confidence: 99%

Influence of the Scanning Strategy on the Microstructure and Mechanical Properties in Selective Electron Beam Melting of Ti–6Al–4V

Scharowsky¹,

Juechter²,

Singer³

et al. 2015

Adv Eng Mater

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“…Zah and Lutzmann [4] and Zah and Kahnert [5] utilized the developed thermal model to investigate various combinations of the process parameters such as the beam scan speed and the beam power to determine the shape of resultant melt pools, which are related to final part microstructures. Zah and Lutzmann [4] and Zah and Kahnert [5] utilized the developed thermal model to investigate various combinations of the process parameters such as the beam scan speed and the beam power to determine the shape of resultant melt pools, which are related to final part microstructures.…”

Section: Introductionmentioning

confidence: 99%

On Process Temperature in Powder-Bed Electron Beam Additive Manufacturing: Process Parameter Effects

Price

Cheng

Lydon

et al. 2014

Journal of Manufacturing Science and Engineering

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On Process T em p eratu re in Pow der-B ed Electron Beam A dditive M anufacturing : Process P a ra m e te r EffectsBuild part certification has been one of the primary roadblocks for effective usage and broader applications of metal additive manufacturing (AM) technologies including powder-bed electron beam additive manufacturing (EBAM). Process sensitivity to oper ating parameters, among others such as powder stock variations, is one major source of property scattering in EBAM parts. Thus, it is important to establish quantitative rela tions between the process parameters and process thermal characteristics that are closely correlated with the AM part properties. In this study, the experimental techniques, fabri cations, and temperature measurements, developed in recent work (Cheng et al., 2014, "On Process Temperature in Powder-Bed Electron Beam Additive Manufacturing: Model Development and Experimental Validation," ASME J. Manuf. Sci. Eng., (in press)) were applied to investigate the process parameter effects on the thermal characteristics in EBAM with Ti-6Al-4V powder, using the system-specific setting called "speed function (SF)" index that controls the beam speed and the beam current during a build. EBAM parts were fabricated using different levels ofSF index (20-65) and examined in the part surface morphology and microstructures. In addition, process temperatures were meas ured by near infrared (NIR) thermography with further analysis of the temperature pro files and the melt pool size. The thermal model, also developed in recent work, was further employed for EBAM temperature predictions, and then compared with the experi mental results. The major results are summarized as follows. SF index noticeably affects the thermal characteristics in EBAM, e.g., a melt pool length o f 1.72 mm and 1.26 mm for SF20 and SF65, respectively, at 24.43 mm build height. SF setting also strongly affects the EBAM part quality including the surface morphology, surface roughness and part microstructures. In general, a higher SF index tends to produce parts of rougher surfaces with more pore features and large /? grain columnar widths. Increasing the beam speed will reduce the peak temperatures, also reduce the melt pool sizes. Simulations conducted to evaluate the beam speed effects are in reasonable agreement compared to the experi mental measurements in temperatures and melt pools sizes. However, the results of a lower SF case, SF20, show larger differences between the simulations and the experi ments, about 58% for the melt pool size. Moreover, the higher the beam current, the higher the peak process temperatures, also the larger the melt pool. On the other hand, increasing the beam diameter monotonically decreases the peak temperature and the melt pool length. 3 Results and Discussion 3.1 Beam Speed Effects. The average translational electron beam speed was calculated, using a method developed [22], for T a b le 1 P a r a m e te r s u s e d in s im u la t io n Parameters Values Scan speed, V (mm/s) Experimentally obtained...

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“…Li et al (2012) showed that increasing the energy density (high power and low scan speed) allows mitigating or avoiding this kind of defect. Regarding EBM, different authors (Scharowsky et al (2015), Zaeh and Kahnert (2009), Puebla et al (2012), Tammas-Williams et al (2015) and Biamino et al (2011) studied the importance of process parameters and scanning strategy of part density, pore morphology and part performances.…”

Section: Processmentioning

confidence: 99%

Process defects andin situmonitoring methods in metal powder bed fusion: a review

Grasso

Colosimo

2017

Meas. Sci. Technol.

619

246

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Despite continuous technological enhancements of metal Additive Manufacturing (AM) systems, the lack of process repeatability and stability still represents a barrier for the industrial breakthrough. The most relevant metal AM applications currently involve industrial sectors (e.g., aerospace and bio-medical) where defects avoidance is fundamental. Because of this, there is the need to develop novel in-situ monitoring tools able to keep under control the stability of the process on a layer-by-layer basis, and to detect the onset of defects as soon as possible. On the one hand, AM systems must be equipped with in-situ sensing devices able to measure relevant quantities during the process, a.k.a. process signatures. On the other hand, in-process data analytics and statistical monitoring techniques are required to detect and localize the defects in an automated way. This paper reviews the literature and the commercial tools for insitu monitoring of Powder Bed Fusion (PBF) processes. It explores the different categories of defects and their main causes, the most relevant process signatures and the in-situ sensing approaches proposed so far. Particular attention is devoted to the development of automated defect detection rules and the study of process control strategies, which represent two critical fields for the development of future smart PBF systems.

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The effect of scanning strategies on electron beam sintering

Cited by 29 publications

References 8 publications

Influence of the Scanning Strategy on the Microstructure and Mechanical Properties in Selective Electron Beam Melting of Ti–6Al–4V

Influence of the Scanning Strategy on the Microstructure and Mechanical Properties in Selective Electron Beam Melting of Ti–6Al–4V

On Process Temperature in Powder-Bed Electron Beam Additive Manufacturing: Process Parameter Effects

Process defects andin situmonitoring methods in metal powder bed fusion: a review

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