Formation Mechanism of AlN Inclusion in High-Nitrogen Stainless Bearing Steels

Lu, Peng-Chong; Li, Huabing; Feng, Hao; Zhu, Hong‐Chun; Liu, Zhuang-Zhuang; He, Tao

doi:10.1007/s11663-021-02171-0

Cited by 44 publications

(13 citation statements)

References 46 publications

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“…It is well known that the solute redistribution between the solid and liquid phases may lead to the sharp increase of solute content in molten steel during solidification, which had a significant effect on the growth of inclusions. The prediction of solutes microsegregation in liquid steel by the Clyne–Kurz model [ 6,28 ] was widely recognized. The formulas of Clyne–Kurz model for the N element are shown as follows

C_{normalN}^{{normalf}_{normals}} = C_{normalN}^{0} {[1 - (1 - 2 Ω k_{normalN}^{{normalf}_{normals}}) f_{normalS}]}^{\frac{(k_{normalN}^{{normalf}_{normals}} - 1)}{(1 - 2 Ω k_{normalN}^{{normalf}_{normals}})}}

where

C_{normalN}^{{normalf}_{normals}}

is the concentration of solute N in residual liquid,

C_{normalN}^{0}

is the initial liquid concentration of N element,

f_{normalS}

is the solid fraction, and

k_{normalN}^{{normalf}_{normals}}

is the partition coefficient for the element N.…”

Section: Methodsmentioning

confidence: 99%

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Effect of Cooling Rate and High N Content on the Precipitation and Growth of AlN Inclusions in Fe–23Mn–2Al–0.08 V High‐Manganese Nonmagnetic Steel

Zhang

Chen

Cheng

et al. 2022

steel research int.

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Industrial experiments are carried out to investigate the precipitation and growth of AlN in Fe–23Mn–2Al–0.08 V steel with nitrogen content up to 80–92 ppm. AlN inclusions can be precipitated before solidification. The morphologies of AlN are mainly divided into hexagonal and needle‐like shapes. With the cooling rate decreasing from 36.66 to 0.71 K s−1, the equivalent diameters of typical AlN increase from 7.56 to 24.20 μm, and the total amount decreases from 203.01 to 60.00 mm−2. The relationship between the cooling rate and the number density is obtained: lnNnormalV=29.848 + 0.453 lnRnormalC. The element segregation analyzed by electronic probe microanalyzer shows that aluminum concentration is low in interdendritic regions but high in dendrites. Aluminum segregation is very weak, and there is almost no nitrogen segregation. Thermodynamic calculation shows that AlN can precipitate before solidification with the nitrogen content higher than 58 ppm. The predicted results of AlN growth by kinetic analysis method can well reveal the growth trend. The nitrogen content (≥58 ppm) has a negligible effect on the size of AlN when the cooling rates are 3.02 and 0.71 K s−1, while the cooling rate has a significant effect on the size of AlN.

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C_{normalN}^{{normalf}_{normals}} = C_{normalN}^{0} {[1 - (1 - 2 Ω k_{normalN}^{{normalf}_{normals}}) f_{normalS}]}^{\frac{(k_{normalN}^{{normalf}_{normals}} - 1)}{(1 - 2 Ω k_{normalN}^{{normalf}_{normals}})}}

where

C_{normalN}^{{normalf}_{normals}}

is the concentration of solute N in residual liquid,

C_{normalN}^{0}

is the initial liquid concentration of N element,

f_{normalS}

is the solid fraction, and

k_{normalN}^{{normalf}_{normals}}

is the partition coefficient for the element N.…”

Section: Methodsmentioning

confidence: 99%

“…Also, the high Al content in steel is easy to lead to the formation of a large number of AlN inclusions. [ 4–6 ]…”

Section: Introductionmentioning

confidence: 99%

Effect of Cooling Rate and High N Content on the Precipitation and Growth of AlN Inclusions in Fe–23Mn–2Al–0.08 V High‐Manganese Nonmagnetic Steel

Zhang

Chen

Cheng

et al. 2022

steel research int.

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“…It is well known that dispersive and fine second-phase particles refine the grains in steel. [11,[14][15][16][17][18][19][20][21][22][23][24][25] As previously mentioned, the number of inclusions smaller than 2 μm in the HN steel was significantly greater than that in the LN steel, and AlN inclusions were formed during the smelting process for the HN steel. The fine AlN inclusions acted as the cores of the heterogeneous nucleation of austenite during the solidification process.…”

Section: Effects Of Nitrogen On Microstructurementioning

confidence: 99%

“…The addition of nitrogen to molten low‐density steel may lead to the formation of nitride inclusions. Lu et al [ 19 ] reported that AlN inclusions form in liquidus steel when the contents of Al and N exceed the critical solubility of AlN inclusions in high‐nitrogen stainless bearing steel. Alba et al [ 20 ] reported that AlN was the dominant inclusion, and the total number of inclusions increased with an increase in the nitrogen content in Fe–5Mn–3Al steel.…”

Section: Introductionmentioning

confidence: 99%

Effects of Nitrogen on the Microstructure and Mechanical Properties of Fe–28Mn–10Al–0.8C Low‐Density Steel

Guo

Zhu

Zhao

et al. 2021

steel research int.

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Herein, the relationships among nitrogen content, inclusion characteristics, microstructure, and mechanical properties of low-density steel are investigated. The austenite grain size is refined with nitrogen addition to the low-density steel, and the ultimate tensile strength, plasticity, fracture toughness, and impact toughness are distinctly enhanced. However, the yield strength decreases due to a decrease in the ferrite content with nitrogen addition. AlN is determined to be the main inclusion in the high-nitrogen low-density steel, and the number percentage of AlN that is less than 2 μm reaches 84%, which promotes the refinement of austenite grains. In addition, aggregated AlN inclusions in the dimples of the steel are observed, which are generated during the smelting process, and the aggregated AlN inclusions tend to cause crack initiation in the low-density steel.

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“…AS one of the widely used aviation bearing materials in recent years, high nitrogen martensite stainless steel 30Cr15Mo1N exhibits high hardness, high strength and toughness, excellent corrosion resistance and fatigue performance, [1][2][3][4] for example, its fatigue life is 5 times that of M50, and the corrosion resistance is 100 times that of 440C. [5] Moreover, 30Cr15Mo1N steel has been successfully applied to the bearings of the fuel pump of space shuttle, the main bearings of aircraft engine, the ball screw of landing gear, the swash plate bearings of helicopter, and so on.…”

Section: Introductionmentioning

confidence: 99%

Effect of Solidification Pressure on Phase Transformation and Precipitated Phases of 30Cr15Mo1N Ingot

Zhu

et al. 2021

Metall Mater Trans B

Self Cite

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In this research, the effect of solidification pressure on phase transformation temperature and sequence, amount of proeutectoid ferrite, characteristics of pearlite and carbonitrides have been investigated by microstructure observation, crystal structure and component analysis, and thermodynamic calculation. The microstructure of 30Cr15Mo1N ingot is mainly composed of martensite, austenite, pearlite, ferrite, M 23 (C,N) 6 and M 2 (C,N). With increasing solidification pressure, M 23 (C,N) 6 precipitation temperature, austenite (c) and ferrite (d) formation temperature increase, and M 2 (C,N) precipitation temperature and ferrite (a) formation temperature decrease. Under 0.5 MPa, the precipitation sequence during solidification process of 30Cr15Mo1N ingot is ''L fi d fi c fi M 2 (C,N) fi M 23 (C,N) 6 fi a + martensite/ retained austenite fi pearlite''. There is a negligible change in phase transformation sequence with increasing solidification pressure from 0.5 to 2 MPa. In addition, the increment in solidification pressure is beneficial to significantly increase the amount of proeutectoid ferrite and reduce pearlite lamellar spacing by enhancing cooling of 30Cr15Mo1N ingot. Meanwhile, with increasing solidification pressure from 0.5 to 2 MPa, the size of M 2 (C,N) and the amount of precipitated phases (pearlite and carbonitrides) have a decreasing trend, and the change in the size of M 23 (C,N) 6 can be neglected.

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Formation Mechanism of AlN Inclusion in High-Nitrogen Stainless Bearing Steels

Cited by 44 publications

References 46 publications

Effect of Cooling Rate and High N Content on the Precipitation and Growth of AlN Inclusions in Fe–23Mn–2Al–0.08 V High‐Manganese Nonmagnetic Steel

Effect of Cooling Rate and High N Content on the Precipitation and Growth of AlN Inclusions in Fe–23Mn–2Al–0.08 V High‐Manganese Nonmagnetic Steel

Effects of Nitrogen on the Microstructure and Mechanical Properties of Fe–28Mn–10Al–0.8C Low‐Density Steel

Effect of Solidification Pressure on Phase Transformation and Precipitated Phases of 30Cr15Mo1N Ingot

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