Quality Related Effects of the Preheating Temperature on Laser Melted High Carbon Content Steels

Zumofen, Livia; Beck, Christian E.; Kirchheim, Andreas; Dennig, Hans-Jörg

doi:10.1007/978-3-319-66866-6_21

Cited by 15 publications

(20 citation statements)

References 6 publications

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“…In case of LPBF-processed AlSi10Mg, the distortion is reduced to zero at a preheating temperature of 250°C, independent of the sample thickness, as illustrated in [17]. At 400°C baseplate temperature, negative deflections of cantilevers are observed for LPBF-processed tool steel 1.2344 (H13), according to the study in [18]. As reported in [19] for stainless steel 1.4540 (PH1) and 1.4404 (316L) LPBF samples, laser shock peening (LSP) effectively changes the residual stress profile from tension to compression.…”

Section: Introductionmentioning

confidence: 77%

“…In this study, cantilever specimens of CM247LC are manufactured with the LPBF process, since they are widely used to analyze residual stresses or upon partly cutting them off the build platform from one end, the distortions, as reported in [11,13,17,18,[26][27][28][29][30][31][32][33][34]. The geometry of the built specimen cantilever is shown in Fig.…”

Section: Distortion Analysismentioning

confidence: 99%

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Residual stress reduction of LPBF-processed CM247LC samples via multi laser beam strategies

Gerstgrasser

Cloots²,

Stirnimann

et al. 2021

Int J Adv Manuf Technol

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Based on SLM parameters from previous works, which guarantee fully dense and crack free CM247LC samples, multi laser beam strategies have been pursued to reduce residual stresses or rather distortion during LPBF processing. By using a second post heating and non-melting laser source with a defocused laser beam and lateral offset, cantilever distortion is reduced more than 7.5%, compared to the reference. Based on pre-tests with 9 different offset parameters, the optimum offset has been identified. Also, an upper limit for the laser power of 65 W is identified for the second heat laser beam with a spot diameter of 380 μm, to avoid re-melting and creating new defects. A theoretical “two bar model,” to explain the residual stress behavior and reduction with multi laser beam offset strategy during the LPBF process, is presented. Furthermore, re-melting cracks, defects, and microstructure are analyzed in conjunction with the second defocused offset laser, in case of a 200 W laser power, an increased scan speed of 1300 mms/s, and a reduced hatch distance. Secondary electron signal (SE) images of re-melting cracks are analyzed and compared to SE-image of hot cracks (solidification cracks). Based on electron backscatter diffraction (EBSD), the results of the microstructure from the last mentioned multi laser beam approach, which creates re-melting cracks, are presented and analyzed.

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Section: Introductionmentioning

confidence: 77%

Section: Distortion Analysismentioning

confidence: 99%

Residual stress reduction of LPBF-processed CM247LC samples via multi laser beam strategies

Gerstgrasser

Cloots²,

Stirnimann

et al. 2021

Int J Adv Manuf Technol

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show abstract

“…Up to now there have been few publications about LPBF of high-speed steel or high carbon steels [7][8][9][10]. Kempen,et al [7] investigate how the preheating temperature influences the part density and the tendency of tool steel M2 (1.3343) with a carbon content of 0.9% to crack.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the authors demonstrate different microstructures with varying hardness within a melt lens and reach a hardness of over 800 HV. In [9] , Zumofen, et al investigate the influence of the preheating temperature on component distortion due to residual stresses by manufacturing cantilevers from M2. The manufacture of the cantilevers at a preheating temperature of 400°C reduces component distortion.…”

Section: Introductionmentioning

confidence: 99%

Feasability Investigation for Laser Powder Bed Fusion of High-Speed Steel AISI M50 with Base Preheating System

Saewe

Gayer

Vogelpoth

et al. 2019

Berg Huettenmaenn Monatsh

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Laser Powder Bed Fusion (LPBF) is an additive manufacturing process employed in the aerospace, automotive, and medical industries. In these sectors, nickel-, aluminium-, and titanium-based alloys are mainly used for various applications. Yet, only few of the commonly used steels have been qualified for the LPBF process in the mechanical engineering industry, which normally uses hot work tool steels with less than 0.5 wt.-% carbon content. However, many applications need high wear-resistant steel alloys with high hardness, both of which can be achieved with a higher carbon content, like in high-speed steels. But when processed with LPBF, these steels often form cracks, making the process very challenging. In this feasibility investigation, we demonstrate that LPBF can be used to manufacture dense and crack-free specimens with a hardness of over 62 HRC (as built) from high-speed steel AISI M50 (carbon content of 0.8 wt.-%). Furthermore, we evaluate the influence of typical LPBF process parameters, especially of preheating temperatures up to 500°C, on the microstructure of the specimens.

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“…The principle of remelting each layer is also investigated which leads to higher martensite content and to more brittle material. Zumhofen et al [7] process M2 using BPPT of 160 -400 °C to manufacture parts with densities of 99 %. By manufacturing Cantilevers at different BPPTs, the residual stresses and distortions were demonstrated.…”

Section: Introduction and State Of The Artmentioning

confidence: 99%

Influence of Preheating Temperature on Hardness and Microstructure of PBF Steel hs6-5-3-8

Saewe¹,

Wilms²,

Jauer³

et al. 2021

Preprint

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Laser powder bed fusion (LPBF) is an additive manufacturing process employed in many industries, for example for aerospace, automotive and medical applications. In these sectors, mainly nickel-, aluminum- and titanium-based alloys are used. In contrast, the mechanical engineering industry is interested in more wear-resistant steel alloys with higher hardness, both of which can be achieved with a higher carbon content, like in high-speed steels. Since these steels are susceptible to cracking, preheating needs to be applied during processing by LPBF. In a previous study, we applied a base plate preheating temperature of 500 °C for HS6-5-3-8 with 1.3 % carbon content. We were able to manufacture dense (p > 99.9 %) and crack-free parts from HS6-5-3-8 with a hardness > 62 HRC (as built) by LPBF. In this study, we investigate the influence of preheating temperatures up to 600 °C on hardness and microstructure dependent on part height for HS6-5-3-8. The microstructure was studied by light optical microscopy (LOM), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The analysis of hardness and microstructure at different part heights is necessary because state-of-the-art preheating systems induce heat only into the base plate. Consequently, parts are subjected to temperature gradients and different heat treatment effects depending on part height during the LPBF process.

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Quality Related Effects of the Preheating Temperature on Laser Melted High Carbon Content Steels

Cited by 15 publications

References 6 publications

Residual stress reduction of LPBF-processed CM247LC samples via multi laser beam strategies

Residual stress reduction of LPBF-processed CM247LC samples via multi laser beam strategies

Feasability Investigation for Laser Powder Bed Fusion of High-Speed Steel AISI M50 with Base Preheating System

Influence of Preheating Temperature on Hardness and Microstructure of PBF Steel hs6-5-3-8

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