Effects of powder recycling on stainless steel powder and built material properties in metal powder bed fusion processes

Jacob, Gregor; Brown, Christopher U.; Donmez, M A.; Watson, Stephanie S.; Slotwinski, John A.

doi:10.6028/nist.ams.100-6

Cited by 48 publications

(47 citation statements)

References 16 publications

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“…The result of an even co-existence of both martensitic and austenitic phases in S17-4 produced in a nitrogen environment is consistent with the XRD results presented by Ref. [51]. Fig.…”

supporting

confidence: 81%

“…Reference [51] found that the amount of the FCC ɣ-austenite in their LPBF parts was approximately 95 %. This large percentage of austenite was attributed to the nitrogen gas atomization to produce the S17-4 powder, which leads to a higher content of nitrogen in the material, as found by Ref.…”

Section: Resultsmentioning

confidence: 99%

“…In another recent study [51], six tensile specimens were fabricated using nitrogen atomized S17-4 powder and the tensile properties of LPBF manufactured S17-4 material (see Fig. 13) were studied.…”

Section: Experimental Validation: S17-4 Manufactured By Lpbfmentioning

confidence: 99%

“…15. Microstructure of AM S17-4 steel using the virgin powder along the build direction at low magnification (A), and high magnification (B) [51].…”

mentioning

confidence: 99%

“…14. Tensile stress strain curves of PBF manufactured S17-4 in stress-relief heat treated conditon; extensometer signal (A) and maximum strain (B) [51].…”

mentioning

confidence: 99%

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Prediction of solidification phases in Cr-Ni stainless steel alloys manufactured by laser based powder bed fusion process

Jacob¹

2018

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The microstructure and strength of chromium-nickel (Cr-Ni) stainless steel alloy parts is highly dependent on the chemical composition of the material and the thermal cycling it experiences during each processing step. This is particularly true when utilizing a laser powder bed fusion (LPBF) process to create the part. LPBF is an additive manufacturing (AM) process that quickly scans a laser over thin layers of powder to melt and solidify the powder to create the part. This results in rapid heating and cooling of the material that is dependent on the processing conditions and part geometry. Consequently, it is necessary to understand how these heating and cooling rates affect the resulting material phases of the final part. Only then the manufacturer can have confidence that the part will perform as intended. The objective of the report is to provide LPBF users with the necessary background to develop processing conditions that will achieve their microstructural design objectives.This report outlines the established methods, using chemical-composition-based phase diagrams (Schäffler and DeLong diagrams), to predict the material microstructure of stainless steel weld metals and applies those methods to LPBF manufactured Cr-Ni stainless steel (S17-4 1 ). Predictions of the solidification phases in Cr-Ni stainless steel alloys, based on the ratio of the Cr and Ni equivalent, are shown. Incorporating these ratios into the phase solidification diagram helps to predict whether the solidification of a Cr-Ni stainless steel occurs in primary ferritic or austenitic phase. This approach also helps users to understand how the increased nitrogen content in additively manufactured S17-4 results in the greater retention of austenite compared to the same material produced by traditional methods. These diagrams can also inform the users about the stability of the retained austenite and its likelihood to decompose into other phases, such as martensite and cementite. In addition to outlining how phase solidification diagrams can help AM users better understand the material they produce, this report also compares results from literature describing microstructure of LPBF fabricated S17-4 with the predicted microstructure before and after different heat treatments. The report also shows that the fine columnar austenitic-martensitic-ferritic microstructure of as-manufactured S17-4 has changed into a predominant martensitic microstructure by a cryogenic treatment, resulting in an increase of hardness.Furthermore, results of mechanical property measurements on additively manufactured S17-4 from other research work are compared and discussed in the result section to explain possibilities of the material phase transformations during different heat treatments, which lead to changes in the mechanical material properties.

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“…The result of an even co-existence of both martensitic and austenitic phases in S17-4 produced in a nitrogen environment is consistent with the XRD results presented by Ref. [51]. Fig.…”

supporting

confidence: 81%

Section: Resultsmentioning

confidence: 99%

Section: Experimental Validation: S17-4 Manufactured By Lpbfmentioning

confidence: 99%

“…15. Microstructure of AM S17-4 steel using the virgin powder along the build direction at low magnification (A), and high magnification (B) [51].…”

mentioning

confidence: 99%

“…14. Tensile stress strain curves of PBF manufactured S17-4 in stress-relief heat treated conditon; extensometer signal (A) and maximum strain (B) [51].…”

mentioning

confidence: 99%

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Prediction of solidification phases in Cr-Ni stainless steel alloys manufactured by laser based powder bed fusion process

Jacob¹

2018

Self Cite

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The Influence of Powder Reuse on the Properties of Laser Powder Bed‐Fused Stainless Steel 316L: A Review

et al. 2022

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There is a clear economic benefit for the recycling of metallic powder during additive manufacturing (AM). Laser powder bed fusion (L‐PBF) is one such AM process and research has found that the properties of the powder feedstock can change when the powder is reused through mechanisms such as spatter generation and alterations in chemistry. Such changes to powder properties can accumulate and may lead to significant differences in the mechanical properties of the final component. Often the changes to part properties are reasonably small; however, there is not currently enough understanding of the specific links between powder properties and the characteristics of the end component for the effects of powder recycling to be discounted. Herein, the typical lifecycle of stainless steel 316L powder in L‐PBF, the changes that occur to the powder feedstock, and the effects that this may have on the mechanical properties of components manufactured with recycled powder are reviewed.

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Function‐on‐function regression for assessing production quality in industrial manufacturing

Palumbo

Centofanti

2020

Quality & Reliability Eng

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Key responses of manufacturing processes are often represented by spatially or time‐ordered data known as functional data. In practice, these are usually treated by extracting one or few representative scalar features from them to be used in the following analysis, with the risk of discarding relevant information available in the whole profile and of drawing only partial conclusions. To avoid that, new and more sophisticated methods can be retrieved from the functional data analysis (FDA) literature. In this work, that represents a contribution in the direction of integrating FDA methods into the manufacturing field, the use of function‐on‐function linear regression modelling is proposed. The approach is based on a finite‐dimensional approximation of the regression coefficient function by means of two sets of basis functions, and two roughness penalties to control the degree of smoothness of the final estimator. The potential of the proposed method is demonstrated by applying it to a real‐life case study in powder bed fusion additive manufacturing for metals to predict the mechanical properties of an additively manufactured artefact, given the particle size distribution of the powder used for its production.

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Effects of powder recycling on stainless steel powder and built material properties in metal powder bed fusion processes

Cited by 48 publications

References 16 publications

Prediction of solidification phases in Cr-Ni stainless steel alloys manufactured by laser based powder bed fusion process

Prediction of solidification phases in Cr-Ni stainless steel alloys manufactured by laser based powder bed fusion process

The Influence of Powder Reuse on the Properties of Laser Powder Bed‐Fused Stainless Steel 316L: A Review

Function‐on‐function regression for assessing production quality in industrial manufacturing

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