Some Theoretical Aspects on Designing Nickel Free High Nitrogen Austenitic Stainless Steels.

Balachandran, G.; Bhatia, M. L.; Ballal, N. B.; Rao, P. Krishna

doi:10.2355/isijinternational.41.1018

Cited by 57 publications

(27 citation statements)

References 18 publications

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“…Reducing the amount of e-martensite formed in the early stages of the deformation is expected to result in a better TRIP effect. For the low Cr alloy in the N 2 annealed condition, the lower value of n [1][2][3][4][5] indicates that the transformation kinetics is indeed slower as a consequence of the increased ISFE. However, the TRIP effect is still limited due to the too low amount of a¢-martensite formed in the later stages of deformation.…”

Section: Discussionmentioning

confidence: 99%

“…In these alternative ferrous alloy systems, the main austenite stabilizing elements are Mn, C, and N. Most of the research in this field has been done on stainless steel grades. [1][2][3][4][5] For some applications, e.g., structural parts in the automotive industry, the corrosion resistance is less important than the deformation behavior and Cr-free austenitic steels are actively being studied. [6,7,8] The automotive applications are mainly related to passive passenger safety systems requiring high energy absorption in the event of a crash.…”

Section: Introductionmentioning

confidence: 99%

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The Influence of Cr and N Additions on the Mechanical Properties of FeMnC Steels

Bracke¹,

Penning

Akdut

2007

Metall Mater Trans A

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The influence of Cr and N additions on the mechanical properties of austenitic Fe-Mn-Cr-C-N alloys was studied. The ductility and the strain-hardening behavior were investigated in detail, because these alloys may potentially be used for crash-relevant automotive body parts. It was found that Cr and low N additions to a Fe-18Mn-0.25C alloy resulted in a higher ductility and a reduced strain hardening. Increasing the N content up to 0.22 mass pct resulted in a further increase of ductility and a more favorable strain-hardening behavior. X-ray diffraction and transmission electron microscopy studies revealed that the strain-hardening behavior was linked to the presence of strain-induced martensite and mechanical twinning. The analysis of the mechanical properties and the microstructure clearly demonstrates that, in the Fe-Mn-Cr-C-N system, both N additions and combined N and Cr additions increase the stacking fault energy.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Influence of Cr and N Additions on the Mechanical Properties of FeMnC Steels

Bracke¹,

Penning

Akdut

2007

Metall Mater Trans A

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“…Чтобы получить аустенит при комнатной темпера-туре химический состав ВАС системы Fe-Cr-Mn-N был выбран исходя из известной фазовой диаграм-мы Шеффлера − ДеЛонга (Schaeffler − DeLong diagram) для нержавеющих сталей [9]. В качестве реагентов при составлении порошковых смесей использовали следующие материалы: оксиды железа Fe 2 O 3 , хрома Cr 2 O 3 , марганца MnO 2 , нитрид хрома (смесь состава 80 % CrN + 20 % Cr 2 N) и порошок алюминиевый марки АСД-Ч.…”

Section: материалы и методы исследованияunclassified

High-nitrogen 23Cr9Мn1N steel manufactured by aluminothermy under nitrogen pressure: structure and mechanical properties

Sapegina¹,

Дорофеев²,

Mokrushina³

et al. 2017

LoM

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High-nitrogen steels are promising materials possessing a combination of high properties of strength, ductility and corrosion resistance. However, a powerful and complex equipment is required for the production of high-nitrogen steels by metallurgy methods under high nitrogen pressure. From energy-saving viewpoint, one of alternative and more attractive techniques is aluminothermy or reduction of metal oxides by metallic aluminum. The high temperature synthesis process occurs in this case due to the chemical energy of exothermic oxidation-reduction reaction. In the present work, the microstructure and mechanical properties of high-nitrogen steel 23Cr9Мn1N (wt.%) produced by aluminothermic SHS-metallurgy under nitrogen pressure using thermodynamic modeling are investigated. The melt was saturated with nitrogen simultaneously from the gas phase and chromium nitrides in the charge. As-cast steel has ferrite-austenitic structure with indications of austenite discontinuous decomposition with Cr 2 N precipitations. The average grain size of the steel is about 16 μm. Forging at T = 1150 -1170°C of the cast steel leads to a refinement of the structure and increase of the austenite fraction in the steel. After heat treatment of the forged sample (quenching in water from 1200°C), there is a single austenite phase. The analysis of change of austenite FCC lattice parameter in the process of structure evolution under hot plastic deformation and heat treatment is carried out. Investigation of mechanical properties shows a combination of high values of strength and plasticity of steel after quenching. A conclusion is drawn that by aluminothermy one can obtain high-nitrogen steel, which has mechanical properties not worse than those of steel obtained by electroslag remelting under a nitrogen pressure. Высокоазотистые стали являются перспективными материалами, обладающими сочетанием высоких свойств проч-ности, пластичности и коррозионной стойкости. Однако для производства высокоазотистой стали методами ме-таллургии под высоким давлением азота требуется энергоемкое и сложное оборудование. С точки зрения энерго-сбережения альтернативным и более привлекательным является метод алюминотермии, восстановления оксидов металлов металлическим алюминием. Высокотемпературный процесс синтеза при этом протекает за счет химиче-ской энергии экзотермической окислительно-восстановительной реакции. В работе исследованы микроструктура и механические свойства высокоазотистой стали 23Cr9Мn1N (мас.%), полученной алюминотермическим методом СВС-металлургии под давлением азота с использованием термодинамического моделирования. Насыщение распла-ва азотом происходило одновременно из газовой фазы и с помощью нитридов хрома в составе шихты. В литом состоянии стали формируется феррито-аустенитная структура с признаками прерывистого распада аустенита с вы-делением Cr 2 N. Средний размер зерна стали ~16 мкм. Ковка при T = 1150 -1170°C литой стали приводит к измель-чению структуры и увеличению доли аустенита в стали. После термообработки кованого образца (закалк...

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“…It is well known that the ductile-to-brittle transition temperature (DBTT) of austenitic Cr-Mn-N stainless steels relies strongly on N content, as strong temperature sensitivity of yield stress and grain boundary strengthening results from the unique effects of N [1,6,7]. According to some empirical equations on DBTT suggested by several researchers [8,9], e.g., DBTT = 300(%N) -303 (°C), the DBTT increases linearly with increasing N content. Therefore, adjustment of N content is necessary to achieve a desired balance of strength and low-temperature toughness of austenitic Cr-Mn-N stainless steels.…”

Section: Introductionmentioning

confidence: 99%

Effects of deformation-induced martensite and grain size on ductile-to-brittle transition behavior of austenitic 18Cr-10Mn-N stainless steels

2010

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Effects of deformation-induced martensite and grain size on ductile-to-brittle transition behavior of austenitic 18Cr-10Mn-(0.3~0.6)N stainless steels with different alloying elements were investigated by means of Charpy impact tests and microstructural analyses. The steels all exhibited ductile-to-brittle transition behavior due to unusual brittle fracture at low temperatures despite having a face-centered cubic structure. The ductileto-brittle transition temperature (DBTT) obtained from Chapry impact tests did not coincide with that predicted by an empirical equation depending on N content in austenitic Cr-Mn-N stainless steels. Furthermore, a decrease of grain size was not effective in terms of lowering DBTT. Electron back-scattered diffraction and transmission electron microscopy analyses of the cross-sectional area of the fracture surface showed that some austenites with lower stability could be transformed to α'-martensite by localized plastic deformation near the fracture surface. Based on these results, it was suggested that when austenitic 18Cr-10Mn-N stainless steels have limited Ni, Mo, and N content, the deterioration of austenite stability promotes the formation of deformationinduced martensite and thus increases DBTT by substantially decreasing low-temperature toughness.

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Some Theoretical Aspects on Designing Nickel Free High Nitrogen Austenitic Stainless Steels.

Cited by 57 publications

References 18 publications

The Influence of Cr and N Additions on the Mechanical Properties of FeMnC Steels

The Influence of Cr and N Additions on the Mechanical Properties of FeMnC Steels

High-nitrogen 23Cr9Мn1N steel manufactured by aluminothermy under nitrogen pressure: structure and mechanical properties

Effects of deformation-induced martensite and grain size on ductile-to-brittle transition behavior of austenitic 18Cr-10Mn-N stainless steels

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