Processing of a newly developed nitrogen-alloyed ferritic-austenitic stainless steel by laser powder bed fusion – Microstructure and properties

Becker, Louis; Röttger, Arne; Boes, J.; Weber, Sebastian; Theisen, W.

doi:10.1016/j.addma.2021.102185

Cited by 12 publications

(8 citation statements)

References 44 publications

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“…Furthermore, nitrogen has major effects on the mechanical properties of DSS, owing to strengthening effects caused by solid-solution strengthening and nitrogen-enhanced grain size strengthening [15]. The positive influence of nitrogen as an alloying element in steels was first reported by Frehser et al [16], and also applies to steels processed via L-PBF [17][18][19].…”

Section: Introductionmentioning

confidence: 97%

Influence of the L-PBF Process Atmosphere on the Microstructure and Tensile Properties of AISI 318LN Duplex Stainless Steel

Mirz

Herzog

Broeckmann

et al. 2022

JMMP

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Duplex stainless steels (DSSs) have excellent mechanical properties, owing to their austenitic–ferritic microstructure. The phase equilibrium strongly depends on solidification conditions and chemical composition, where elemental nitrogen significantly stabilizes the austenitic phase. When DSSs are processed by laser powder bed fusion (L-PBF) under an argon atmosphere, the rapid cooling rates result in an undesirable fully ferritic microstructure. To better understand the microstructure formation, this study examined the influence of the L-PBF process atmosphere on the porosity, microstructure, and mechanical properties of DSS AISI 318LN. Gaseous argon and nitrogen were used as a protective atmosphere, and specimens were analyzed in the as-built and post-processed conditions via optical and electron microscopy, electron backscatter diffraction, and tensile testing. Specimens processed under a nitrogen atmosphere showed a lower initial density in the as-built conditions, and tended to form more lack-of-fusion and gas pores compared to specimens processed under argon. The different defect types in nitrogen-processed specimens were still present after solution-annealing and quenching, leading to a 13% lower tensile strength and 43% lower elongation at fracture. Differences in phase equilibrium caused by the process atmosphere could not be established. All differences in porosity can be minimized by hot isostatic pressing, thus resulting in comparable mechanical properties of argon- and nitrogen-processed specimens.

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Section: Introductionmentioning

confidence: 97%

Influence of the L-PBF Process Atmosphere on the Microstructure and Tensile Properties of AISI 318LN Duplex Stainless Steel

Mirz

Herzog

Broeckmann

et al. 2022

JMMP

View full text Add to dashboard Cite

show abstract

“…[2,3,11] However, the significant consumption of expensive nickel element and their negative effect on biocompatibility requires the development of nickel-saving or nickel-free stainless steels. Boes et al [12][13][14][15][16][17] developed several types of stainless steels with the introduction of nitrogen, carbon, and manganese to partially replace nickel or eliminate nickel by LPBF. The austenitic and ferritic-austenitic microstructures can be produced via the partial substitution of Ni by Mn [17] or the mixture of austenitic stainless steel powders and super duplex stainless steel powders in different proportions.…”

Section: Introductionmentioning

confidence: 99%

“…Boes et al [12][13][14][15][16][17] developed several types of stainless steels with the introduction of nitrogen, carbon, and manganese to partially replace nickel or eliminate nickel by LPBF. The austenitic and ferritic-austenitic microstructures can be produced via the partial substitution of Ni by Mn [17] or the mixture of austenitic stainless steel powders and super duplex stainless steel powders in different proportions. [18] The printing pores, microstructure, mechanical properties, and corrosion resistance were characterized in the previous studies.…”

Section: Introductionmentioning

confidence: 99%

“…[18] The printing pores, microstructure, mechanical properties, and corrosion resistance were characterized in the previous studies. [13,17] It was found that the introduction of nitrogen tends to increase porosity due to the limited solubility of nitrogen in the steel matrix. [13,14] Although extensive efforts had been made to tune the microstructure for improving mechanical properties in the Ni-saving stainless steels via compositional engineering before or during LPBF processing, a comprehensive LPBF synthesis and characterization for high manganese and nitrogen stainless steels is yet to investigate in terms of cracks and microstructure such as texture anisotropy and grain boundary character.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis and Characterization of Innovative Fe–Cr–Mn Ferritic Stainless Steel by Laser Powder Bed Fusion

et al. 2023

steel research int.

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Crack development for laser-fused metallic materials is one major challenge for laser-based powder bed fusion (LPBF). The cracks are manifested in two forms, i.e., macrocracks along building layers due to spalling and microcracks along the high-angle grain boundaries. To mitigate the crack formation, a new type of ferritic stainless steel Fe-Cr-Mn are synthesized by LPBF. The well-developed columnar ferrite grains with an enhanced fine acicular austenite precipitation, which possess Nishiyama-Wassermann (N-W) orientation relationship with the ferrite matrix, can be readily produced when the laser energy density is beyond 100 J mm À3 . Porosity can be further reduced below 0.5% by optimizing the laser power and scanning speed. It is found that laser rescanning may eliminate the cracks without modifying the grain morphology, crystallographic texture, and phase distribution.

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Numerical Studies of Influencing Factors on the Homogeneity of the Powder Mixture during the Powder Spreading Process of Powder Bed Fusion–Laser Beam/Metal

Deng,

Sang,

Zhang

et al. 2024

Adv Eng Mater

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Recent studies have focused on the alloying of nitrogen (N) in high‐alloy stainless steels by powder bed fusion–laser beam/metal (PBF‐LB/M). However, N‐induced pore formation remains a challenge. To overcome this, a combined PBF‐LB/M and hot isostatic pressing (HIP) process is developed. AISI 304L stainless steel powder was mixed with silicon nitride (Si3N4) powder and processed by PBF‐LB/M, allowing partial retention of Si3N4. This helps to maintain sufficient N content while reducing pore formation. The microstructure is then homogenised by HIP. A major challenge of this process is to maintain the homogeneity of the deposited powder mixture on the powder bed to ensure a consistent N content in the final products. This study combines experimental and numerical methods to address this issue: scanning electron microscopy is used to characterize the microstructure and map the local N content, while various numerical studies based on the discrete element method are carried out to investigate the effects of layer thickness, substrate surface roughness, and powder properties on the intermediate product. The numerical approach effectively predicts the N content distribution and homogeneity on the powder bed. The models are validated with experimental data and optimal process conditions for PBF‐LB/M are identified.

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Processing of a newly developed nitrogen-alloyed ferritic-austenitic stainless steel by laser powder bed fusion – Microstructure and properties

Cited by 12 publications

References 44 publications

Influence of the L-PBF Process Atmosphere on the Microstructure and Tensile Properties of AISI 318LN Duplex Stainless Steel

Influence of the L-PBF Process Atmosphere on the Microstructure and Tensile Properties of AISI 318LN Duplex Stainless Steel

Synthesis and Characterization of Innovative Fe–Cr–Mn Ferritic Stainless Steel by Laser Powder Bed Fusion

Numerical Studies of Influencing Factors on the Homogeneity of the Powder Mixture during the Powder Spreading Process of Powder Bed Fusion–Laser Beam/Metal

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