Metal injection molding (MIM) of high-speed tool steels

Myers, N.S.; Heaney, Donald F.

doi:10.1533/9780857096234.4.516

Cited by 9 publications

(8 citation statements)

References 11 publications

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“…The average densities of the refractory ballast sintered samples after 10 s, 30 s, 1 min, and 4 min is 66.4%, 83.1%, 92.1%, and 99.9%, respectively, whereas the samples sintered in a vacuum after 10 s, 30 s, 1 min, and 6 min are 64.7%, 78.9%, 90.2%, and 99.8%, respectively. The driving force to densify the powder compacts at the sintering temperatures is the reduced surface energy caused by the formation of intergranular bonds, reducing the surface area [ 35 , 49 ]. Under both conditions, the specimens follow the same kinetics as other sintering strategies conducted on powder metallurgy, consisting of three clearly identified stages.…”

Section: Resultsmentioning

confidence: 99%

“…The solid-state sintering of powder compacts results from the reduced surface energy of particles in close proximity, whereby mass transport diffusion takes place, with the most common approach performed through solid-state furnace sintering [ 35 ]. Other highly effective routes have been developed more recently, such as microwave sintering [ 36 , 37 ], Spark Plasma Sintering (SPS) or Field-Assisted Sintering (FAST) [ 38 ], or via direct [ 39 , 40 , 41 ] or indirect [ 42 , 43 ] induction.…”

Section: Introductionmentioning

confidence: 99%

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Indirect Induction Sintering of Metal Parts Produced through Material Extrusion Additive Manufacturing

et al. 2023

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Avoiding loose powders and resins, material extrusion additive manufacturing is a powerful technique to produce near-net shape parts, being a cheap and safe alternative for developing complex industrial-grade products. Filaments embedded with a high packing density of metallic or ceramic granules are being increasingly used, resulting in almost fully dense parts, whereby geometries are shaped, debinded and sintered sequentially until the completion of the part. Traditionally, “brown” debinded geometries are transported to conventional furnaces to densify the powder compacts, requiring careful tailoring of the heating profiles and sintering environment. This approach is decoupled and often involves time-consuming post-processing, whereby after the completion of the shaping and debinding steps, the parts need to be transported to a sintering furnace. Here, it is shown that sintering via indirect induction heating of a highly filled commercially available filament embedded with stainless steel 316L powder can be an effective route to densify Fused Filament Fabricated (FFF) parts. The results show that densities of 99.8% can be reached with very short soaking times, representing a significant improvement compared to prior methods. A hybrid machine is proposed, whereby a custom-built machine is integrated with an induction heater to combine FFF with local indirect induction sintering. Sintering in situ, without the need for part transportation, simplifies the processing of metal parts produced through material extrusion additive manufacturing.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Indirect Induction Sintering of Metal Parts Produced through Material Extrusion Additive Manufacturing

et al. 2023

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“…The fundamental principle guiding this selection is achieving a suitable balance between densification and structural integrity and ensuring minimal shape distortion. The pseudo phase diagram for AISI M2 tool steel helps determine optimal sintering temperatures by indicating critical phase transitions [53,54]. At around 1300 • C, a combination of liquid (L), alpha-ferrite (α), and gamma-austenite (γ) is formed, promoting densification through capillary action.…”

Section: Printing Curing Debinding and Sinteringmentioning

confidence: 99%

Enhancing Quality Control: Image-Based Quantification of Carbides and Defect Remediation in Binder Jetting Additive Manufacturing

Choudhari,

Elder,

Mugale

et al. 2024

Materials

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While binder jetting (BJ) additive manufacturing (AM) holds considerable promise for industrial applications, defects often compromise part quality. This study addresses these challenges by investigating binding mechanisms and analyzing common defects, proposing tailored solutions to mitigate them. Emphasizing defect identification for effective quality control in BJ-AM, this research offers strategies for in-process rectification and post-process evaluation to elevate part quality. It shows how to successfully process metallic parts with complex geometries while maintaining consistent material properties. Furthermore, the paper explores the microstructure of AISI M2 tool steel, utilizing advanced image processing techniques like digital image analysis and SEM images to evaluate carbide distribution. The results show that M2 tool steel has a high proportion of M6C carbides, with furnace-cooled samples ranging from ~2.4% to 7.1% and MC carbides from ~0.4% to 9.4%. M6C carbides ranged from ~2.6% to 3.8% in air-cooled samples, while water-cooled samples peaked at ~8.52%. Sintering conditions also affected shrinkage, with furnace-cooled samples showing the lowest rates (1.7 ± 0.4% to 5 ± 0.4%) and water-cooled samples showing the highest (2 ± 0.4% to 14.1 ± 0.4%). The study recommends real-time defect detection systems with autonomous corrective capabilities to improve the quality and performance of BJ-AM components.

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“…5(a-c). Organic polymers must be completely removed from the "green part", as carbon residues can influence the sintering process and negatively affect the quality of the final product [27].…”

Section: Debinding and Sinteringmentioning

confidence: 99%

Solid-State and Super Solidus Liquid Phase Sintering of 4340 Steel SLM Powders Shaped by Fused Filament Fabrication

et al. 2022

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4340 steel powders were processed with an additive manufacturing process using the FFF (Fused Filament Fabrication) technique. A composite filament was developed to print samples and study the effect of the bed and nozzle temperatures on its physical and microstructural properties. The printed samples were debinded and sintered by: Solid State (SS) at 1300 °C or SLPS (Supersolidus Liquid Phase Sintering) at 1420 °C. Metallography and scanning electron microscopy (SEM) identified the microstructure and phases. The hardness of the sintered samples was measured with the Vickers method. The SLPS process contributes to better densification and volume contraction; however, it promotes geometrical distortion of the samples compared to the SS samples. The microstructure of the sintered samples consists of ferrite situated in the original austenite grain and bainite. The sintering mechanism significantly influenced the hardness of the samples. Finally, a part was designed, printed, debinded, and sintered with the aim of studying the maximum inclination angle, the minimum vertical and horizontal holes, and the minimum vertical layer thickness, which can be obtained through the whole process.

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Metal injection molding (MIM) of high-speed tool steels

Cited by 9 publications

References 11 publications

Indirect Induction Sintering of Metal Parts Produced through Material Extrusion Additive Manufacturing

Indirect Induction Sintering of Metal Parts Produced through Material Extrusion Additive Manufacturing

Enhancing Quality Control: Image-Based Quantification of Carbides and Defect Remediation in Binder Jetting Additive Manufacturing

Solid-State and Super Solidus Liquid Phase Sintering of 4340 Steel SLM Powders Shaped by Fused Filament Fabrication

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