Gas atomization and laser additive manufacturing of nitrogen-alloyed martensitic stainless steel

Boes, J.; Röttger, Arne; Theisen, W.; Cui, Chengsong; Uhlenwinkel, Volker; Schulz, A.; Zoch, H.‐W.; Stern, Felix; Tenkamp, Jochen; Walther, Frank

doi:10.1016/j.addma.2020.101379

Cited by 17 publications

(7 citation statements)

References 62 publications

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“…The chemical composition of the as-built parts is very close to that of the corresponding initial powders and powder mixtures. The nitrogen content of the as-built parts is slightly lower than that of the powders, indicating possible degassing during PBF-LB/M (as reported by Boes et al [26]). The chemical composition of the as-built samples was determined using S-OES (QSG750, OBLF GmbH, Witten, Germany) and the results are given in Table 4.…”

Section: Porosity Of As-built Parts and Process Windowsupporting

confidence: 58%

Laser Additive Manufacturing of Duplex Stainless Steel via Powder Mixture

Cui

Becker

Gärtner

et al. 2022

JMMP

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Laser additively manufactured duplex stainless steels contain mostly ferrite in the as-built parts due to rapid solidification of the printed layers. To achieve duplex microstructures (ferrite and austenite in roughly equal proportions) and, thus, a good combination of mechanical properties and corrosion resistance, an austenitic stainless steel powder (X2CrNiMo17-12-2) and a super duplex stainless steel powder (X2CrNiMoN25-7-4) were mixed in different proportions and the powder mixtures were processed via PBF-LB/M (Laser Powder Bed Fusion) under various processing conditions by varying the laser power and the laser scanning speed. The optimal process parameters for dense as-built parts were determined by means of light optical microscopy and density measurements. The austenitic and ferritic phase formation of the mixed alloys was significantly influenced by the chemical composition adjusted by powder mixing and the laser energy input during PBF-LB/M. The austenite content increases, on the one hand, with an increasing proportion of X2CrNiMo17-12-2 in the powder mixtures and on the other hand with increasing laser energy input. The latter phenomenon could be attributed to a slower solidification and a higher melt pool homogeneity with increasing energy input influencing the phase formation during solidification and cooling. The desired duplex microstructures could be achieved by mixing the X2CrNiMo17-12-2 powder and the X2CrNiMoN25-7-4 powder at a specific mixing ratio and building with the optimal PBF-LB/M parameters.

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Section: Porosity Of As-built Parts and Process Windowsupporting

confidence: 58%

Laser Additive Manufacturing of Duplex Stainless Steel via Powder Mixture

Cui

Becker

Gärtner

et al. 2022

JMMP

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“…In another recent study, Boes et al studied nitrogen alloyed martensitic stainless steel. 12 In this research they also showed nitrogen escaping the material during L-PBF and report brittle behaviour during fatigue testing. They also show delta-ferritic solidification taking place in Scheil-Gulliver simulations for the investigated martensitic stainless steel.…”

Section: Introductionmentioning

confidence: 52%

Nitrogen alloyed austenitic Ni-free stainless steel for additive manufacturing

Antikainen,

Jokiaho,

Lagerbom

et al. 2024

Powder Metallurgy

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Nitrogen alloyed austenitic nickel-free stainless steel (ANFSS) is one of the most promising group of materials for consumer and healthcare products. They can be used to substitute not only conventional AISI 316L, but also more expensive titanium and Co-Cr alloys. Previously the utilization of nitrogen alloyed materials has been limited due to poor machinability resulting from high strength and ductility, and difficulties in manufacturing the nitrogen alloyed raw materials. Recent developments in powder metallurgy, for example, additive manufacturing (AM), offer feasible net shape manufacturing routes to go around machining and material related challenges. The present study investigates and introduces a viable processing route for an ANFSS by gas atomization, direct energy deposition (DED), and sintering. Special attention is paid to control the nitrogen content in different processing steps by investigating a Fe-16Mn-14Cr-0.27C-0.35N alloy with experimental and computational methods. The results show that the nitrogen content can be computationally estimated and maintained at desired level by proper selection of processing parameters, and thereby controlling the final nitrogen content of the ANFSS alloy.

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“…MAT is a short time procedure to obtain information about the fatigue behavior by additionally measuring the material's reaction [21] which was already successfully used for different PBF-LB materials. [19,22] In this case, stress-strain behavior was measured with a tactile extensometer (l 0 ¼ 10 mm). By that, plastic strain amplitude ε a,p and total strain amplitude ε a,t can be used to describe the mechanical material reaction in every step as well as with increasing stress after each step.…”

Section: Fatigue Testingmentioning

confidence: 99%

“…Nevertheless, hardness increased significantly, especially after tempering twice at 590 °C for 2 h. Compressive yield strength of tempered specimens was increased to 1990 MPa compared to specimens without increased N which only reached 1225 MPa in as‐built condition. A prealloyed martensitic steel X30CrMoN15‐1 was characterized by Boes et al [ 19 ] which was gas atomized under N atmosphere and afterward processed by PBF‐LB/M. N‐content also decreased from powder to PBF‐LB/M specimen from 0.18 to 0.14 mass% as the steel solidifies primary in the ferritic phase which results in a much lower N solubility.…”

Section: Introductionmentioning

confidence: 99%

Improving the Defect Tolerance of PBF‐LB/M Processed 316L Steel by Increasing the Nitrogen Content

et al. 2022

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Nitrogen (N) in steels can improve their mechanical strength by solid solution strengthening. Processing N‐alloyed steels with additive manufacturing, here laser powder bed fusion (PBF‐LB), is challenging as the N‐solubility in the melt can be exceeded. This degassing of N counteracts its intended positive effects. Herein, the PBF‐LB processed 316L stainless steel with increased N‐content is investigated and compared to PBF‐LB 316L with conventional N‐content. The N is introduced into the steel by nitriding the powder and mixing it with the starting powder to achieve an N‐content of approximately 0.16 mass%. Thermodynamic calculations for maximum solubility to avoid N outgassing and pore formation under PBF‐LB conditions are performed beforehand. Based on the results, a higher defect tolerance under fatigue characterized by Murakami model can be achieved without negatively influencing the PBF‐LB processability of the 316L steel. The increased N‐content leads to higher hardness (+14%), yield strength (+16%), tensile strength (+9%), and higher failure stress in short time fatigue test (+16%).

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Gas atomization and laser additive manufacturing of nitrogen-alloyed martensitic stainless steel

Cited by 17 publications

References 62 publications

Laser Additive Manufacturing of Duplex Stainless Steel via Powder Mixture

Laser Additive Manufacturing of Duplex Stainless Steel via Powder Mixture

Nitrogen alloyed austenitic Ni-free stainless steel for additive manufacturing

Improving the Defect Tolerance of PBF‐LB/M Processed 316L Steel by Increasing the Nitrogen Content

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