A study of microstructure and cracking behavior of H13 tool steel produced by laser powder bed fusion using single-tracks, multi-track pads, and 3D cubes

He, Yining; Zhong, Ming; Beuth, Jack; Webler, Bryan A.

doi:10.1016/j.jmatprotec.2020.116802

Cited by 48 publications

(17 citation statements)

References 19 publications

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“…dT = −350K at the terminal range (Figure 1(a)). This gradient is much lower as compared to H13 tool steel (−2364 K), which was found to form solidification cracks during LBPF processing [29], and even lower than that of highly printable 316L [6] (−506 K). While the low solidification gradient results in less susceptibility to solidification cracking, the narrow freezing range reduces the chemical segregation, reducing the risk of liquation cracking.…”

mentioning

confidence: 81%

Alloy design against the solidification cracking in fusion additive manufacturing: an application to a FeCrAl alloy

Dovgyy

Simonelli

Pham

2021

Materials Research Letters

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This study developed a design methodology against liquid-state cracking by combining the Scheil-Gulliver solidification simulations and Machine Learning analysis to design alloys for Fusion Additive Manufacturing. Applying this design approach resulted in a Fe-20Cr-7Al-4Mo-3Ni. The alloy was successfully printed with relative densities of over 99%. Microstructure of printed material was extensively characterised through scanning and transmission electron microscopy, energy dispersive spectroscopy and x-ray diffraction, confirming a single-phase material with low texture and negligible chemical segregation. Neither solidification nor liquation cracks were detected, supporting the validity of the methodology, however, the alloy suffered from solid-state cracking, hindering the ductility. IMPACT STATEMENTA design methodology against solidification and liquation cracking and chemical segregation to assist the alloy design for Additive Manufacturing.

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mentioning

confidence: 81%

Alloy design against the solidification cracking in fusion additive manufacturing: an application to a FeCrAl alloy

Dovgyy

Simonelli

Pham

2021

Materials Research Letters

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“…The experiments are carried out without powder. He et al [21] show that experiments without powder are transferable to PBF-LB/M. Adding powder leads to a small shift of the process window due to a slightly more pronounced balling tendency [21].…”

Section: Feedstock Materialsmentioning

confidence: 99%

“…In addition, it is qualitatively determined whether balling effects occur. Depending on the weld track geometries, the specimens are classified into one or more of the following categories adapted from [8,21] (see Figure 6):…”

Section: Cross-sectional Geometriesmentioning

confidence: 99%

Influence of Ring-Shaped Beam Profiles on Process Stability and Productivity in Laser-Based Powder Bed Fusion of AISI 316L

Grünewald

Gehringer

Schmöller

et al. 2021

Metals

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A major factor slowing down the establishment of additive manufacturing processes as production processes is insufficient reproducibility and productivity. Therefore, this work investigates the influence of ring-shaped beam profiles on process stability and productivity in laser-based powder bed fusion of AISI 316L. For this purpose, the weld track geometries of single tracks and multi-track segments with varying laser power, scan speed, hatch distance, and beam profile (Gaussian profile and three different ring-shaped profiles) are analyzed. To evaluate the process robustness, process windows are identified by classifying the generated single tracks into different process categories. The influence of the beam profiles on productivity is studied by analyzing the molten cross-sectional areas and volumes per time. When using ring-shaped beam profiles, the process windows are significantly larger (up to a laser power of 1050 W and a scanning speed of 1700 mm/s) than those of Gaussian beams (laser power up to 450 W and scanning speed up to 1100 mm/s), which suggests a higher process robustness and stability. With ring-shaped beam profiles, larger volumes can be stably melted per track and time. The weld tracks created with ring-shaped profiles are significantly wider than those generated with Gaussian profiles (up to factor 2 within the process window), allowing enlargement of the hatch distances. Due to the higher scanning speeds and the enlarged hatch distances for ring-shaped beam profiles, the process can be accelerated by a factor of approximately 2 in the parameter range investigated.

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“…Conventional tooling steel such as H13, [ 3,4 ] H11, [ 5,6 ] and AISI420 [ 7–9 ] have been successfully used to manufacture small parts (<100 mm) but large parts remain a challenge and these materials are more likely to have cracks due to high residual stresses. [ 10 ] One option to reduce the residual stresses is to heat the building plate above 200 °C [ 11 ] ; however, the heat treatment on the part will then not be homogenous throughout the part, which could lead to a reduction of the mechanical performance and higher porosity rates due to temperature variations. [ 12,13 ]…”

Section: Introductionmentioning

confidence: 99%

“…Conventional tooling steel such as H13, [3,4] H11, [5,6] and AISI420 [7][8][9] have been successfully used to manufacture small parts (<100 mm) but large parts remain a challenge and these materials are more likely to have cracks due to high residual stresses. [10] One option to reduce the residual stresses is to heat…”

Section: Introductionmentioning

confidence: 99%

Development of a New Tooling Steel (L40) for Laser Powder Bed Fusion: Influence of Particle Size Distribution and Powder Atomization on Mechanical Performance

et al. 2021

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Additive manufacturing (AM) is widely used for tooling applications: Complex conformal cooling channels are designed to increase and homogenize the cooling rate of a mold insert. The list of available steel grades in laser powder bed fusion is currently very limited and does not satisfy highly mechanically demanding applications; hard stainless steel metals printable without cracking are lacking. Herein, the influence of the particle size distribution and atomization process on the printability of a new tooling steel tailored for AM (L40) is observed on an EOS M290 printer based on microstructural observations and mechanical testing. Several batches with different powder size distributions of either gas‐ or water‐atomized powder are processed and studied. The aim of using water‐atomized powder is to reduce both the environmental footprint and the cost of the feed material. Dense built parts (other 99% density) are achieved using water‐ and gas‐atomized powders. The hardness is in all cases superior to 50 HRC, which is above the standard requirement for injection molding applications. The ductility of gas‐atomized parts is four times higher than that measured on heat‐treated maraging steel. Water‐atomized samples reach a ductility similar to that of maraging steel.

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A study of microstructure and cracking behavior of H13 tool steel produced by laser powder bed fusion using single-tracks, multi-track pads, and 3D cubes

Cited by 48 publications

References 19 publications

Alloy design against the solidification cracking in fusion additive manufacturing: an application to a FeCrAl alloy

Alloy design against the solidification cracking in fusion additive manufacturing: an application to a FeCrAl alloy

Influence of Ring-Shaped Beam Profiles on Process Stability and Productivity in Laser-Based Powder Bed Fusion of AISI 316L

Development of a New Tooling Steel (L40) for Laser Powder Bed Fusion: Influence of Particle Size Distribution and Powder Atomization on Mechanical Performance

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