Improving Structural Integrity with Boron-based Additives for 3D Printed 420 Stainless Steel

Do, Truong; Shin, Chang Seop; Stetsko, Dalton; VanConant, Grayson; Vartanian, Aleksandr; Pei, Shenli; Kwon, Patrick

doi:10.1016/j.promfg.2015.09.019

Cited by 38 publications

(12 citation statements)

References 12 publications

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“…The material system used in this study employed a solid powder binder, which is intended to dissolve when exposed to the liquid binder and thus create stronger adhesive bonds between metal particles in the green state. If an appropriate amount of binder is used, these bonding sites can promote sinter neck initiation during the metal sintering process [5,59].…”

Section: Effect Of Am Process Parameters On Green Densitymentioning

confidence: 99%

“…Green parts are sintered in controlled conditions, which results in the burnout of all the binder and the formation of sinter necks between the powder particles, leading to a higher density part. BJAM of metals has been receiving lower lower part densities, in the range of 50 -99% [1][2][3][4][5][6][7][8][9]. The BJAM technology has been used with a wide range of metals and alloys, such as iron or steel [2-5, 7, 10-24], titanium [6,8,[25][26][27][28][29][30][31], nickel [9,[32][33][34][35], copper [1,15], lead [36,37], zirconium [38], zinc [39], gold [40] and magnetic neodymium-iron-boron [41], in addition to composite metal materials [42][43][44][45].…”

Section: Accepted Manuscript 1 Introductionmentioning

confidence: 99%

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Tailoring green and sintered density of pure iron parts using binder jetting additive manufacturing

Rishmawi

Salarian

Vlasea

2018

Additive Manufacturing

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Binder jetting additive manufacturing (BJAM) is a comparatively low-cost process that enables manufacturing of complex and customizable metal parts. This process is applied to low-cost wateratomized iron powder with the goal of understanding the effects of printing parameters and sintering schedule on maximizing the green and sintered densities of manufactured samples respectively. The powder is characterized by using scanning electron microscopy (SEM) and particle size analysis (Camsizer X2). In the AM process, the effects of powder compaction, layer thickness and liquid binder level on green part density are investigated. Post-process heat treatment is applied to select samples, and suitable debinding parameters are studied by using thermogravimetric analysis (TGA). Sintering at various temperatures and durations results in densities of up to 91.3%. Image processing of x-ray computed tomography (μCT) scans of the samples reveals that porosity distribution is affected by powder spreading, and gradients in pore distribution in the sample are largely reduced after sintering. The resulting shrinkage ranges between 6.7  3.0% and 25.3  2.8%, while surface roughness ranges between 11.6  5.0 μm and 32.1  3.4 μm. The results indicate that the sintering temperature and time might be tailored to achieve target densities anywhere in the range of 64% and 91%, with possibly higher densities by increasing sintering time.

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Section: Effect Of Am Process Parameters On Green Densitymentioning

confidence: 99%

Section: Accepted Manuscript 1 Introductionmentioning

confidence: 99%

Tailoring green and sintered density of pure iron parts using binder jetting additive manufacturing

Rishmawi

Salarian

Vlasea

2018

Additive Manufacturing

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“…The final part density was significantly improved by incorporating BN powder. Based on prior experimental studies [31], adding 0.5% wt. BN to the SS powder mixture increased the final part density to 93% at a lower sintering temperature of 1250°C with negligible distortion.…”

Section: Resultsmentioning

confidence: 99%

“…Thus, BJP does not induce residual stress or distortions in the part [29]. A modified processing protocol was used to improve the part density and surface finish as previously reported [30, 31]. Molds were fabricated using either a pure stainless steel (SS) 420 powder mixture, with average diameters of 30 μm (Oerlikon, Troy, MI) and 6 μm (Epson Atmix Corp., Hachinohe, Japan), or SS powder mixtures containing varying concentrations of 1 μm-diameter boron nitride (BN) powder (Sigma-Aldrich, St. Louis, MO).…”

Section: Methodsmentioning

confidence: 99%

3D printed metal molds for hot embossing plastic microfluidic devices

Lin

Kwon

et al. 2017

Lab Chip

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Plastics are one of the most commonly used materials for fabricating microfluidic devices. While various methods exist for fabricating plastic microdevices, hot embossing offers several unique advantages including high throughput, excellent compatibility with most thermoplastics and low start-up costs. However, hot embossing requires metal or silicon molds that are fabricated using CNC milling or microfabrication techniques which are time consuming, expensive and required skilled technicians. Here, we demonstrate for the first time the fabrication of plastic microchannels using 3D printed metal molds. Through optimization of the powder composition and processing parameters, we were able to generate stainless steel molds with superior material properties (density and surface finish) than previously reported 3D printed metal parts. Molds were used to fabricate poly(methyl methacrylate) (PMMA) replicas which exhibited good feature integrity and replication quality. Microchannels fabricated using these replicas exhibited leak-free operation and comparable flow performance as those fabricated from CNC milled molds. The speed and simplicity of this approach can greatly facilitate the development (i.e. prototyping) and manufacture of plastic microfluidic devices for research and commercial applications.

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“…At the same time, a lack or excess of carbon causes the stainless steel microstructure to deviate from the standard, and in turn leads to unexpected mechanical properties [13]. The 420 stainless steel is a ferrite/martensite stainless steel that requires extremely accurate carbon control [14]. Proper carbon content could enlarge the sintering temperature range (within the γ + MC + L phase); thus, a sample with a high density and low grain size could be obtained.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Decarburization Behaviour during the Sintering of Metal Injection Moulded 420 Stainless Steel

Lou

Liu

et al. 2020

Metals

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The decarburization behaviour during the sintering of metal-injection-moulded 420 stainless steel was investigated. Particular attention has been paid to the decarburization mechanisms and carbon distribution of parts sintered at different temperatures. The results indicate that the loss of carbon content occurs mainly through the reduction of surface oxides of powder particles or reaction with the atmosphere. Depending on the densification level, the sintering decarburization is separated into two stages. Below 1200 °C, decarburization occurs at the powder particle surface. The surface oxides react with the amorphous carbon or residual organics to pose the metal surface. At this time, the carbon content distribution of the sintered body is similar to that of the as-debound sample. The reduction of surface oxides promotes sintering. At 1200 °C, the densification speed is higher in the centre region of the sample, where the interconnected pores close and the second stage of decarburization takes place. At temperatures above 1200 °C, carbon atoms in the inner layers must migrate to the surface to react with the atmosphere. The decarburization speed is reduced and the carbon content distribution of the as-sintered part is similar to that of the dense decarburized part.

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Improving Structural Integrity with Boron-based Additives for 3D Printed 420 Stainless Steel

Cited by 38 publications

References 12 publications

Tailoring green and sintered density of pure iron parts using binder jetting additive manufacturing

Tailoring green and sintered density of pure iron parts using binder jetting additive manufacturing

3D printed metal molds for hot embossing plastic microfluidic devices

Investigation of Decarburization Behaviour during the Sintering of Metal Injection Moulded 420 Stainless Steel

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