Nitrogen Steels and High‐Nitrogen Steels: Industrial Technologies and Properties

Svyazhin, A. N.; Капуткина, Л. М.; Smarygina, I. V.; Капуткин, Д. Е.

doi:10.1002/srin.202200160

Cited by 12 publications

(9 citation statements)

References 29 publications

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“…The dynamic viscosity of the melt decreases as the temperature of the molten pool rises when the energy density is high, and at the same time, the recoil effect of the laser beam on the molten pool is enhanced. This enhances the disturbance effect of the high-temperature molten pool and encourages nitrogen escape [22]. Further analysis reveals that the selective laser melting is occurring at a pressure that is relatively close to that of ambient air (about 25 mbar higher than ambient pressure).…”

Section: Nitrogen Concentration and Phase Evolutionmentioning

confidence: 94%

Section: Nitrogen Concentration and Phase Evolutionmentioning

confidence: 99%

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Process Parameter Optimization for Selective Laser-Melted High-Nitrogen Steel and the Effects on Microstructure and Properties

Sun

Ren

Wang

et al. 2023

Metals

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Chromium nitride powder is blended with pre-alloyed powder to make an overmatched powder with a high nitrogen concentration in order to manufacture high-nitrogen steel by selective laser melting. By employing a wider range of process parameters, the impact of process parameters on the relative density, nitrogen concentration, microstructure, and mechanical properties of high-nitrogen steel is investigated. In simulated human body fluid conditions, the corrosion resistance of high-nitrogen steel, pure titanium, and 316L was compared and evaluated. The findings demonstrate that the relative density of high-nitrogen steel initially rises and then falls with the increase in energy density, reaching a high value of 98.8% at 148.8 J/mm3. With rising energy density, the nitrogen concentration falls. The microstructure of high-nitrogen steel is mainly composed of columnar and cellular grains. Both grain sizes steadily grow, but their mechanical characteristics initially rise and then fall as the energy density rises from 83.3 to 187.3 J/mm3. With yield strength, tensile strength, and elongation reaching 921.9 MPa, 1205.1 MPa, and 27%, respectively, the alloy exhibits outstanding mechanical characteristics when the laser power is 250 W, the scanning speed is 700 mm/s, and the associated energy density is 148.8 J/cm3. The high-nitrogen steel at an energy density of 148.8 J/mm3 has the lowest corrosion rate when compared to pure titanium and 316L steel, which suggests that the HNS alloy will have good corrosion resistance in human body fluid conditions.

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Section: Nitrogen Concentration and Phase Evolutionmentioning

confidence: 94%

Section: Nitrogen Concentration and Phase Evolutionmentioning

confidence: 99%

Process Parameter Optimization for Selective Laser-Melted High-Nitrogen Steel and the Effects on Microstructure and Properties

Sun

Ren

Wang

et al. 2023

Metals

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“…Blowing nitrogen into the ladle from the bottom is a common method to manufacture nitrogen alloyed austenitic steels. [ 28 ] Owing to the rapid melting and cooling rate (about 10 6 K s −1 ) [ 29 ] involved in the SLM process, there are bound to be violent metallurgical reactions, mass transfer, and heat transfer between gas, solid, and liquid. However, most of the existing investigations assumed that the protective atmosphere does not participate in the metallurgical reactions.…”

Section: Introductionmentioning

confidence: 99%

Processing Fundamentals and Performance Investigation of Selective Laser Melting of High‐Speed Steel in Reactive N₂ Atmosphere

Zhang

Sun

Gao

et al. 2023

steel research int.

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The selective laser melting (SLM), also termed as laser powder bed fusion (LPBF), is attractive for its ability to fabricate complex metallic components with great geometrical design freedom and manufacturing capacity. [1,2] The high heating/cooling rate and thermal input of laser processing result in refined grain and tailored microstructure, [3] leading to a notable Hall-Petch effect and improved mechanical performance of manufactured parts. Furthermore, SLM provides an effective way for the design and fabrication of high performance metal matrix composites (MMCs), wherein varieties of reinforced particles, [4,5] carbon nanotube, [6] and whiskers [7] can be added to metals, alloys, and even intermetallics through both ex situ and in situ approaches. [8] High speed steels (HSS) [9] are widely used in the production of cutting tools, drilling tools, extrusion molds, precision dies, and high temperature bearings due to their combination of high hardness (>60 HRC), strength (bending strength >2000 MPa), and wear resistance (high amount of carbides). In recent years, SLM of high speed steel, cold work die steel, hot work die steel, and similar tool and die steels has gained significant attention due to its ability to produce complicated parts and implementation of individually forming internal cooling channels. [10,11] This can significantly increase the cooling efficiency, application reliability, and service life of SLM-manufactured tools and molds. However, the available data in the literature [12,13] have shown that high speed steels are prone to cracking during the SLM cyclic remelting process with fast cooling rates due to their high carbon content (ranging from 0.8 to >3 wt%), [14] large amount of strong carbide forming elements, and thermal residual stress. The microstructure of SLM-processed high speed steel usually consists of martensite, retained austenite, carbides, and possibly eutectic structures. [15] In addition, Saewe et al. [16] found that the temperature gradients in the SLM process create grain growth in the build direction, resulting in columnar dendritic crystal, which can cause brittleness and promote crack formation. Recent results produced by Platl et al. [17] suggest the cracks propagate predominantly along the network of M 2 C eutectic carbide deposited at the grain boundaries of carbon martensite and retained austenite matrix. They indicated that the stress-induced cracking of eutectic carbides, which emerge from the tensile stress accumulations during solidification and cooling stages, is the predominant cracking mechanism of the LPBF-processed tool steel. Therefore, several studies focus on the additional preheating [18,19] during the SLM process to reduce the cumulative tensile stress and residual stresses. Among these studies,

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“…High-nitrogen stainless steel (HNSS) is widely used in manufacturing, biomedical, marine engineering, and military industries owing to its good mechanical and corrosion resistance. [1][2][3][4][5] As a strong austenite-stabilizing element, N has a favorable solid-solution strengthening effect. [6] Moreover, it can increase the strength of stainless steel by 2-4 times without affecting its ductility and toughness.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Mold Powders for High‐Nitrogen Stainless Steel Based on Mold Thermocouple Temperature Variation

Chen

Wen

Tang

et al. 2023

steel research int.

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High‐nitrogen stainless steel (HNSS) is prone to surface depression during continuous casting; however, its high‐temperature solidification characteristics and mold powder design have not been reported. Based on the analysis of mold thermocouple temperature variation, this study clarifies the high‐temperature solidification characteristics of HNSS and the cause of surface depression. It optimizes the mold powder for HNSS continuous casting according to factory and laboratory research. The factory trials indicate that the mold thermocouple temperature at the corresponding location decreases by 6.0–20.9 °C when the slab surface is depressed. The analysis shows that the high initial solidification strength of HNSS causes its slab surface depressions. Owing to this characteristic, the mold powder for HNSS should have a suitable melting rate, low basicity, and proper Al2O3. This low‐basicity Al2O3‐containing slag has a crystal slag film near the mold side and a thick liquid slag film near the slab. It can both provide good lubrication and control horizontal heat transfer.

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Nitrogen Steels and High‐Nitrogen Steels: Industrial Technologies and Properties

Cited by 12 publications

References 29 publications

Process Parameter Optimization for Selective Laser-Melted High-Nitrogen Steel and the Effects on Microstructure and Properties

Process Parameter Optimization for Selective Laser-Melted High-Nitrogen Steel and the Effects on Microstructure and Properties

Processing Fundamentals and Performance Investigation of Selective Laser Melting of High‐Speed Steel in Reactive N₂ Atmosphere

Optimization of Mold Powders for High‐Nitrogen Stainless Steel Based on Mold Thermocouple Temperature Variation

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Nitrogen Steels and High‐Nitrogen Steels: Industrial Technologies and Properties

Cited by 12 publications

References 29 publications

Process Parameter Optimization for Selective Laser-Melted High-Nitrogen Steel and the Effects on Microstructure and Properties

Process Parameter Optimization for Selective Laser-Melted High-Nitrogen Steel and the Effects on Microstructure and Properties

Processing Fundamentals and Performance Investigation of Selective Laser Melting of High‐Speed Steel in Reactive N2 Atmosphere

Optimization of Mold Powders for High‐Nitrogen Stainless Steel Based on Mold Thermocouple Temperature Variation

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Processing Fundamentals and Performance Investigation of Selective Laser Melting of High‐Speed Steel in Reactive N₂ Atmosphere