L-PBF of 4340 Low Alloy Steel: Influence of Feedstock Powder, Layer Thickness, and Machine Maintenance

Jelis, Elias; Hespos, Michael R.; Groeschler, Shana; Carpenter, Ryan

doi:10.1007/s11665-018-3739-2

Cited by 13 publications

(4 citation statements)

References 4 publications

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“…A number of low-alloy steels have already been successfully processed with LB-PBF, including HY100 [9], AF9628 [10], 4130 [11], 4140 [12–14] and 4340 [1516]. These studies indicate that build plate preheating is advised to successfully minimise cold cracking within the as-built components.…”

Section: Introductionmentioning

confidence: 99%

Laser-based powder bed fusion of non-weldable low-alloy steels

2021

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This study focuses on the processability of four low-alloy steels (AISI 4130, 4140, 4340 and 8620) via laser-based powder bed fusion (LB-PBF). In the as-built condition, the alloys consisted of tempered martensite that was the result of an intrinsic heat treatment (IHT) during LB-PBF. In terms of defects, a distinct transition in porosity was observed that correlated to the volumetric energy density (VED). At low VED, specimens contained a lack of fusion porosity, while at high VED, they contained keyhole porosity. Additionally, cold cracking was observed in 4140 and 4340 specimens produced at low/intermediate VEDs. This cracking could be mitigated by increasing the VED or laser power, as both enhance the IHT. This enhanced IHT lowered the material hardness below specific thresholds (<500HV 4340 and <460 4140), increasing ductility and allowing the specimens to avoid cracking. From these findings, crack-free, high-density (>99.8%) low-alloy steel specimens were produced without the requirement of build plate preheating.

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Section: Introductionmentioning

confidence: 99%

Laser-based powder bed fusion of non-weldable low-alloy steels

2021

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“…Therefore, omitting and having inadequate maintenance activities of manufacturing equipment can affect an organisation's long‐term profitability . For example, an inadequate maintained AM machine can lead to poor recoating performance, resulting in products with lower mechanical properties and higher quality variability, representing a potential threat to the patient and a serious financial issue to the company …”

Section: Resultsmentioning

confidence: 99%

Quality by Design for industry translation: Three‐dimensional risk assessment failure mode, effects, and criticality analysis for additively manufactured patient‐specific implants

Martinez-Marquez

Terhaer

Scheinemann

et al. 2020

Engineering Reports

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The complexity of patient-specific implants combined with the current limited expertise in reliability engineering and manufacturability in the additive manufacturing (AM) sector is posing a number of quality performance challenges.Worldwide medical device regulatory bodies are facing increasing pressure to devise adequate standards to ensure long-term patient safety and product performance. The implementation of the Quality by Design (QbD) system to titanium 3D-printed bone implants offers a proven system to ensure that products are designed and manufactured correctly from the beginning without errors. This article reports on the development of a failure mode, effects, and criticality analysis (FMECA) coupled with a 3D risk assessment approach. This integrated approach is based on a questionnaire performed with three industry firms and three university research groups with significant experience and expertise in medical device product development and/or research in this field. Research outcomes include a FMECA form containing 137 failure modes with AM materials, AM machine general, fabrication, electron beam melting machine, finishing, and design being as the most sensitive process areas in terms of product quality. We subsequently propose corresponding preventive and corrective strategies for risk mitigation. The approach forms part of the QbD system being developed by the authors specifically for additive manufactured titanium patient-specific implants. K E Y W O R D Sadditive manufacturing, criticality analysis, failure mode effects, patient-specific implants, quality by designThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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“…Powder loading and recycling prevents material contamination and increases operator safety [64]. Another new improvement to increase work safety is refining inert argon on the atmosphere and using airlocks to make sure the powder particles up to 5 μm size are processed safely [52, [65][66][67].…”

Section: New Technologies To Provide User-friendly and Safety For Systemmentioning

confidence: 99%

A review of technological improvements in laser-based powder bed fusion of metal printers

Khorasani

Gibson

Veetil

et al. 2020

Int J Adv Manuf Technol

150

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Additive manufacturing (AM) is an emerging process that has been extremely improved in terms of technology and application in recent years. In this technology review, new industrial improvements in laser powder bed fusion (LPBF) of metals are discussed. LPBF has the lowest build rate among all AM processes that produce metals such as electron beam powder bed fusion, direct energy deposition, binder jetting and sheet lamination. The findings of the current research show that the most innovations and future directions of LPBF printers are toward increasing the speed of the process by using interchangeable feedstock chamber, closed-loop control powder handling, automated powder sieving, multi-layer concurrent printing, 2-axis coating and multi powder hoppers. To increase the speed of the process, the new improvements for transferring time and using fast lasers are presented. Another innovation in the building of LPBF printers is enhancing part quality by improving lasers with the shorter beam diameter, multi-lasers, uniform inert gas flow, accurate positioning systems, using high vacuum systems and using sensors and automation.

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L-PBF of 4340 Low Alloy Steel: Influence of Feedstock Powder, Layer Thickness, and Machine Maintenance

Cited by 13 publications

References 4 publications

Laser-based powder bed fusion of non-weldable low-alloy steels

Laser-based powder bed fusion of non-weldable low-alloy steels

Quality by Design for industry translation: Three‐dimensional risk assessment failure mode, effects, and criticality analysis for additively manufactured patient‐specific implants

A review of technological improvements in laser-based powder bed fusion of metal printers

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