The Effect of Heating Rate on Subsurface AlN Formation in Fe-Al Alloys in N2-O2 Atmospheres

Bott, June H.; Yin, Hang; Sridhar, Seetharaman

doi:10.1007/s11663-014-0116-x

Cited by 5 publications

(9 citation statements)

References 9 publications

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“…This is particularly important during the non-isothermal part of the heat treatment and shows a nice qualitative agreement with the change of the surface porosity at different heating rates. Furthermore, findings in pure Fe-Al alloys also report a higher Al concentration close to the surface during faster heating [4] which may help accelerate the formation of volatile species.…”

Section: B Effect Of Heating Ratementioning

confidence: 96%

“…However in dry nitrogen/oxygen, the composition of the surface in binary iron-aluminum [4] clearly changes with faster heating rates. In the same atmosphere, the porosity of the oxide layer in TRIP steel increases with faster heating rates, as shown in Figure 3.…”

Section: B Effect Of Heating Ratementioning

confidence: 98%

“…[4] Cross sections of TRIP steel, oxidized in dry nitrogen/oxygen, can be seen in Section III-B ( Figure 5(a)). Severe corrosive attack only occurred in the reheat furnace atmosphere, [16] showing massive formation of iron oxides at the surface.…”

Section: A Effect Of Gas Atmospherementioning

confidence: 99%

“…The proposed mechanisms from literature, leading to volatilization of aluminum oxide [23] , are shown in Eqs. [1] through [4]:…”

Section: B Effect Of Heating Ratementioning

confidence: 99%

“…[1][2][3] Especially in complex atmospheres like in a slab reheat furnace, a fundamental understanding of the corrosion behavior of materials like advanced highstrength steels or low-density steels with a high aluminum content [4] represents a significant technical advantage. Besides the many works on the effect of humidity, [5,6] a clear technical benefit for steel manufacture is still missing.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Gas Composition and Exposure Cycle on the Formation of Surface and Subsurface Oxides in Iron-Aluminum-Based Alloys at High Temperatures

Bott

Yin

Sridhar

et al. 2016

Metall Mater Trans B

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The slab reheating process of binary iron-aluminum alloys and an industrial TRIP steel grade has been investigated in both dry and wet atmospheres. The presence of water vapor has a significant effect on the overall scale growth and internal corrosion depth. Heating rate greatly influences the porosity of the surface oxide layer with the surface getting more porous at faster heating rates. Nitride formation could be suppressed in the presence of water vapor, leading to a reduction of internal corrosion depth and a better formability of the final material. Experimental results were compared to thermodynamic predictions and critically discussed.

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Section: B Effect Of Heating Ratementioning

confidence: 96%

Section: B Effect Of Heating Ratementioning

confidence: 98%

Section: A Effect Of Gas Atmospherementioning

confidence: 99%

“…The proposed mechanisms from literature, leading to volatilization of aluminum oxide [23] , are shown in Eqs. [1] through [4]:…”

Section: B Effect Of Heating Ratementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of Gas Composition and Exposure Cycle on the Formation of Surface and Subsurface Oxides in Iron-Aluminum-Based Alloys at High Temperatures

Bott

Yin

Sridhar

et al. 2016

Metall Mater Trans B

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Effects of the Cooling Rate and Recovery Temperature on the Growth of AlN Precipitates in Gear Steel

Shen

Cheng

Hou

et al. 2022

steel research int.

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During the continuous casting and rolling process of gear steel, AlN precipitation often causes surface cracks on the cast slab. Rapid cooling of the slab surface is a new concept to inhibit AlN and improve the cracking resistance, but it requires further investigation for practical application. Here, the effects of the cooling rate and recovery temperature on AlN growth behavior in gear steel are investigated by designing five cooling conditions. A mathematical model to describe the growth characteristics is constructed based on Ostwald ripening theory. The experimental results show that the cooling rate significantly influences the size and quantity of AlN. When the cooling rate increases from 3.0 to 5.0 °C s−1, the average diameter of AlN decreases from 133.6 to 75.8 nm and the number density of AlN decreases from 6.8 × 105 to 2.1 × 105 cm−2. The calculated results show that AlN has maximum size, which significantly decreases with decreasing temperature. When AlN reaches the maximum size, it stops growing. AlN growth during the cooling process mainly occurs above 800 °C. Therefore, a high cooling rate and a recovery temperature lower than 800 °C are key to inhibiting AlN precipitation and improving the cracking resistance.

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Embrittlement Analysis of $$\sum {{{{5}\left[ {{21}0} \right]} \mathord{\left/ {\vphantom {{{5}\left[ {{21}0} \right]} {\left( {\overline{1}\overline{2}0} \right)}}} \right. \kern-\nulldelimiterspace} {\left( {-{1}-{2}0} \right)}}}$$ FeAl Grain Boundary in Presence of Defects: An Ab Initio Study

Lehankari

Aravindh

Cao

et al. 2021

Metall Mater Trans A

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Iron aluminide (FeAl) inter-metallic compounds are potential candidates for structural applications at high temperatures owing to their superior corrosion resistance, high temperature oxidation, low density and inexpensive material cost. However, the presence of defects can lead to reduction in the strength and ductility of FeAl-based materials. Here we present a density functional theory (DFT) study of the effect of the presence of defects including Fe and Al vacancies as well as H dopants at the substitutional and interstitial sites at a $$\sum {{{{5}\left[ {{21}0} \right]} \mathord{\left/ {\vphantom {{{5}\left[ {{21}0} \right]} {\left( {\overline{1}\overline{2}0} \right)}}} \right. \kern-\nulldelimiterspace} {\left( {\overline{1}\overline{2}0} \right)}}}$$ ∑ 5 210 / 1 ¯ 2 ¯ 0 FeAl grain boundary focusing on the energetics. The plane wave pseudopotential code Vienna Ab initio Simulation Package (VASP) in the generalized gradient approximation (GGA) is used to carry out the computations. The formation energy calculations showed that intrinsic defects such as Fe and Al vacancies probably form at the GB, indicated by their negative formation energies. These vacancies can further form defect complexes with H impurities, indicated by lowered formation energies, compact bonds and charge gain of H atoms. Electronic structure analysis showed stronger hybridization of 1s orbitals of H with Fe and Al atoms, which leads to the stabilization of these defects resulting in degradation of material strength.

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The Effect of Heating Rate on Subsurface AlN Formation in Fe-Al Alloys in N2-O2 Atmospheres

Cited by 5 publications

References 9 publications

Influence of Gas Composition and Exposure Cycle on the Formation of Surface and Subsurface Oxides in Iron-Aluminum-Based Alloys at High Temperatures

Influence of Gas Composition and Exposure Cycle on the Formation of Surface and Subsurface Oxides in Iron-Aluminum-Based Alloys at High Temperatures

Effects of the Cooling Rate and Recovery Temperature on the Growth of AlN Precipitates in Gear Steel

Embrittlement Analysis of $$\sum {{{{5}\left[ {{21}0} \right]} \mathord{\left/ {\vphantom {{{5}\left[ {{21}0} \right]} {\left( {\overline{1}\overline{2}0} \right)}}} \right. \kern-\nulldelimiterspace} {\left( {-{1}-{2}0} \right)}}}$$ FeAl Grain Boundary in Presence of Defects: An Ab Initio Study

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