An austenite-rich composite of stainless steels with high strength and favorable ductility via selective laser melting of a powder mixture

Fang, Yongjian; Zhang, Yali; Kim, Min-Kyeom; Kim, Hyung-ick; No, Jonghwan; Duan, Zhijian; Yuan, Quan; Suhr, Jonghwan

doi:10.1016/j.msea.2022.143891

Cited by 8 publications

(3 citation statements)

References 56 publications

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“…This is because when the N 2 shielding gas was used during the LPBF process, the water molecules on the powders in HP60 could cause the formation of oxide film, preventing the reaction of N 2 gas with the 17-4PH powders [30]. Additionally, a higher amount of carbon and nitrogen elements in the DP3.4 specimen (Table 4) could promote the formation of the γ phase through austenitic solidification mode [46] compared to HP60. Consequently, the fraction of the γ phase in DP3.4 was found to be greater than that in HP60 by up to approximately 4.05 wt.%.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

Moisture Effects on Qualities and Properties of Laser Powder Bed Fusion (LPBF) Additive Manufacturing of As-Built 17-4PH Stainless Steel Parts

Kim,

Fang

et al. 2023

Metals

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Laser powder bed fusion (LPBF) has the advantages of high resolution and geometric freedom but can be susceptible to process failures and defects caused by inappropriate process parameters and powder conditions. This study aims to reveal and quantify the moisture effect on the qualities and properties of as-built parts with various process parameters. The results showed that the density was decreased by 7.86% with humid powder (60.0% relative humidity (RH)) compared to dry powder (3.4%RH). Expectedly, the observed low density led to the property degradation in the hardness, yield strength (YS), and ultimate tensile strength (UTS) of the humid powder by 11.7, 15.02, and 21.25%, respectively, compared to that of dry powder (3.4%RH). Interestingly, the elongation at break of the parts fabricated with humid powder (60.0%RH) was increased by 2.82%, while their YS and UTS were decreased significantly. It seems that the water molecules on the powder surface hindered the reaction between the N2 shielding gas and melted powder, which resulted in the reduction in the austenite (γ) phase by up to 4.05 wt.%. This could be mainly responsible for the decrease in both the YS and UTS of the humid powder by approximately 100 and 150 MPa, respectively. This study demonstrates that the moisture of the metal powder used for LPBF should be carefully controlled to ensure desirable as-built qualities and properties.

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Section: Mechanical Propertiesmentioning

confidence: 99%

Moisture Effects on Qualities and Properties of Laser Powder Bed Fusion (LPBF) Additive Manufacturing of As-Built 17-4PH Stainless Steel Parts

Kim,

Fang

et al. 2023

Metals

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“…It can be concluded that the recrystallization phenomenon of matrix grains plays an important role in the microstructure and properties of LPBF-fabricated particle-reinforced MMCs, and the matrix containing larger particles (>1 µm) can possess a higher dislocation density and stored energy for recrystallization behavior. Therefore, it should be noted that sufficient submicron-or micron-sized particles can be designed to be formed in the matrix, because they can contribute to recrystallization behavior based on particle stimulated nucleation (PSN) [194]. In general, for the in situ heat treatment induced by the LPBF process, the existence of submicron and nanoparticles has the ability to block the movement of sub-grain boundaries as well as the rearrangement of dislocations, which can retard the recrystallization of matrix grains [177].…”

Section: Recrystallization Behavior Of Mmcs During Lpbf Processmentioning

confidence: 99%

Strategies and Outlook on Metal Matrix Composites Produced Using Laser Powder Bed Fusion: A Review

Kim,

Fang,

Kim

et al. 2023

Metals

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Particle-reinforced metal matrix composites (MMCs) produced using the laser powder bed fusion (LPBF) technique have gained considerable attention because of their distinct attributes and properties in comparison with conventional manufacturing methods. Nevertheless, significant challenges persist with LPBF-fabricated MMCs: more design parameters over commercially available alloys and several defects resulting from inappropriate process conditions. These challenges arise from the intricate interaction of material- and process-related phenomena, requiring a fundamental understanding of the LPBF process to elucidate the microstructural evolution and underlying mechanisms of strengthening. This paper provides a comprehensive overview of these intricate phenomena and mechanisms, aiming to mitigate the process-related defects and facilitate the design of MMCs with enhanced mechanical properties. The material processing approach was suggested, covering from material design and LPBF to postprocessing. Furthermore, the role of in situ heat treatment on the microstructure evolution of MMCs was clarified, and several novel, potential strengthening theories were discussed for the LPBF-fabricated MMCs. The suggested strategies to address the challenges and design high-performance MMCs will offer an opportunity to develop promising LPBF-fabricated MMCs, while overcoming the material limitations of LPBF.

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“…Hence, some metal particles are added instead. Fang et al [ 15 ] used a powder mixture of 310 S and 430 SS to prepare γ-Fe composite materials through LPBF. However, the increase in strength of the formed LPBF SS was not significant due to the limited strength of SS materials.…”

Section: Introductionmentioning

confidence: 99%

Effects of Mo Particles Addition on the Microstructure and Properties of 316 L Stainless Steels Fabricated by Laser Powder Bed Fusion

Zhang

Wang

et al. 2023

Materials

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Application of the 316 L stainless steel (SS) is limited by its relatively low wear resistance, insufficient strength, and poor corrosion resistance in special environments. To this end, effects of Mo particles addition on the microstructure, mechanical properties, and corrosion resistance of the laser powder bed fusion (LPBF) 316 L SS are investigated in this study. The results show that the addition of Mo particles from 0 wt.% to 10 wt.% can modify the crystal orientation and improve the strength, wear resistance, and corrosion resistance of LPBF 316 L SSs. Particularly, the LPBF 316 L SS forms a biphasic structure with a similar ratio of α-Fe to γ-Fe with 5 wt.% Mo addition. As a result, the corresponding samples possess both the excellent toughness of austenitic SSs and the high strength and corrosion resistance of ferrite SSs, which reaches a high tensile strength of about 830 MPa, together with a low friction coefficient of 0.421 μ. Since the Mo particles addition is beneficial to increase the content of Cr2O3 on the samples surface from 13.48% to 22.68%, the corrosion current density of 316 L SS decreases by two orders of magnitude from 569 nA to 6 nA, while the mechanical properties remain favorable. This study is expected to serve as a reference for the preparation of LPBF SSs with excellent integrated performance.

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An austenite-rich composite of stainless steels with high strength and favorable ductility via selective laser melting of a powder mixture

Cited by 8 publications

References 56 publications

Moisture Effects on Qualities and Properties of Laser Powder Bed Fusion (LPBF) Additive Manufacturing of As-Built 17-4PH Stainless Steel Parts

Moisture Effects on Qualities and Properties of Laser Powder Bed Fusion (LPBF) Additive Manufacturing of As-Built 17-4PH Stainless Steel Parts

Strategies and Outlook on Metal Matrix Composites Produced Using Laser Powder Bed Fusion: A Review

Effects of Mo Particles Addition on the Microstructure and Properties of 316 L Stainless Steels Fabricated by Laser Powder Bed Fusion

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