Mechanism of bake hardening in ultralow carbon steel containing niobium and titanium additions

Baker, L.; Parker, J.D.; Daniel, Smitha

doi:10.1179/026708302225001741

Cited by 33 publications

(28 citation statements)

References 5 publications

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“…(10) Vale ressaltar que, para um processo controlado pela difusão do carbono na ferrita, para a formação de atmosferas nas deslocações, seriam esperados valores de m em torno de 2/3 e de energia de ativação entre 76 kJ/mol e 90 kJ/mol. (11) Com relação ao segundo estágio de envelhecimento, o valor de energia de ativação encontrado, 118 ± 10 kJ/mol, está de acordo com os resultados de energia de ativação obtidos por Waterschoot, Verbeken e De Cooman (12) (123,8 kJ/mol) e Cheng et al (13) (111 kJ/mol -126 kJ/mol), para o estágio de precipitação de carbonetos de transição, carboneto ε e/ou carboneto η, durante o revenimento da martensita na faixa de temperatura entre 120°C e 200°C. Em linha com esses resultados, também foi obtida por Lement e Cohen, (14) uma lei cinética, segundo o modelo de Harper, com o expoente do tempo igual a 0,5, para a formação do carboneto ε durante o revenimento da martensita, baseando-se em um modelo controlado pela difusão induzida por gradiente de concentração.…”

Section: Resultsunclassified

Estudo Do Envelhecimento Após Deformação Em Um Aço Dual Phase De Baixa Resistência Mecânica Laminado a Frio

Murari¹,

Melo²,

Gonzalez³

2009

TMM

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ResumoA cinética de envelhecimento após deformação em aço Dual Phase laminado a frio é estudada por meio de ensaios de tração. Após a etapa de recozimento contínuo, o aço foi pré-deformado de 0,5% em tração e envelhecido no intervalo de temperatura entre 50°C e 185°C, para tempos variando entre 1 minuto e 4.915 minutos. O aço estudado apresenta dois estágios de envelhecimento, o primeiro, entre 50°C e 125°C (para tempos inferiores a 72 minutos) e o segundo entre 125°C (para tempos superiores a 72 minutos) e 185°C. As variações no valor Bake Hardening sugerem, para o primeiro estágio de envelhecimento, um processo controlado pelo ancoramento das deslocações na ferrita devido à formação de clusters e/ou carbonetos de transição, com uma energia de ativação próxima de 70 kJ/mol e obedecendo a uma lei cinética descrita pela equação de Harper com expoente do tempo igual a 0,4. No segundo estágio de envelhecimento, o fenômeno é controlado pelo revenimento da martensita. A energia de ativação correspondente a esse estágio é de cerca de 120 kJ/mol e sua cinética pode ser descrita pela mesma equação, porém com um expoente do tempo igual a 0,5. Palavras-chave: Aço bifásico; Envelhecimento após deformação; Bake hardening. STATIC STRAIN AGING STUDY IN A COLD ROLLED DUAL PHASE STEEL OF LOW MECHANICAL RESISTANCE AbstractThe kinetics of static strain aging in cold rolled Dual Phase steel is studied by means of tensile tests. After the continuous annealing step, the specimens were pre-strained with a tensile strain of 0.5% and then aged in the temperature range of 50°C to 185°C and time intervals ranging from 1 minute to 4,915 minutes. The steel studied showe two strain aging stages: the first one between 50°C and 125°C (for times shorter than 72 minutes) and the second one between 125°C (for times longer than 72 minutes) and 185°C. The changes in the Bake Hardening values suggest, for the first stage, a process controlled by the locking of the dislocations in the ferrite due to the formation of clusters and/ or transition carbides, with an activation energy close to 70 kJ/mol and following a kinetic law described by the Harper equation with a time exponent of 0.4. In the second stage, the phenomenon is controlled by tempering of martensite. The corresponding activation energy is approximately 120 kJ/mol and the kinetics of this stage can be described by the same equation, however with a time expoent of 0.5.

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Section: Resultsunclassified

Estudo Do Envelhecimento Após Deformação Em Um Aço Dual Phase De Baixa Resistência Mecânica Laminado a Frio

Murari¹,

Melo²,

Gonzalez³

2009

TMM

View full text Add to dashboard Cite

show abstract

“…5) and also reported elsewhere. 10,23,25) Hundy 27) showed that in case of temper rolling reduction Ͻ3%, the deformation was not uniform and that alternate band of heavily worked and annealed metal exist perpendicular to the rolling direction causing the generation of residual micro-stress. Relaxation of this micro-stress generated during temper rolling might control the aging behaviour in temper rolled condition.…”

Section: Aging Behaviourmentioning

confidence: 99%

“…Sudden rise in Del-Y can be assumed to be due to precipitation of carbide but the rise of YP-EL simultaneously is not expected in this stage as per the existing knowledge. 4,[22][23][24] It appears that slow rate of rise of Del-Y or YP-EL up to certain period is due to temper rolling effect. In case of tensile deformation, a much higher rate of strain aging has been observed in steel A (Fig.…”

Section: Aging Behaviourmentioning

confidence: 99%

A Simple Method for Prediction of Shelf Life of Bake Hardening Steels

2008

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“…Pechler et al [6] confirmed that the ULC bake-hardening (ULC-BH) steel shows significantly better mechanical properties than the low carbon (LC) bake hardening steel. Scientists [7][8][9][10][11][12][13][14] studied the dissolution and precipitation of carbides in the steels during the annealing cycle using the internal friction technique. Pan and Hosbons [13] provided a comprehensive description on the determination of the concentration of solute carbon and nitrogen in ferrite, and the evaluation method of strain aging susceptibility in low carbon steels.…”

Section: Introductionmentioning

confidence: 99%

“…The internal friction is measured using subresonant technique in an inverted torsion pendulum [7][8][9][10][11][12]14,35].…”

Section: Introductionmentioning

confidence: 99%

Relationship Between Bake Hardening, Snoek-Köster and Dislocation-Enhanced Snoek Peaks in Coarse Grained Low Carbon Steel

Zhao

Zhang

et al. 2016

Archives of Metallurgy and Materials

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In the present work, specimens prepared from coarse grained low carbon steel with different prestrains were baked and then, their bake hardening (BH) property and internal friction were determined. TeM was used to characterize the dislocation structure in BH treated samples. The measurements of internal friction in prestrained samples and baked samples were carried out using a multifunctional internal friction apparatus. The results indicate that, in coarse grained low carbon steel, the bake hardening properties (BH values) were negative, which were increased by increasing the prestrain from 2 to 5%, and then were decreased by increasing the prestrain from 5 to 10%. In the specimen with prestrain 5%, the BH value reached the maximum value and the height of Snoek-Köster peak was observed to be the maximum alike. With increasing the prestrain, both of the BH value and Snoek-Köster peak heights are similarly varied. It is concluded that Snoek-Köster and dislocation-enhanced Snoek peaks, caused by the interactions between interstitial solute carbon atoms and dislocations, can be used in further development of the bake hardening steels.

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Mechanism of bake hardening in ultralow carbon steel containing niobium and titanium additions

Cited by 33 publications

References 5 publications

Estudo Do Envelhecimento Após Deformação Em Um Aço Dual Phase De Baixa Resistência Mecânica Laminado a Frio

Estudo Do Envelhecimento Após Deformação Em Um Aço Dual Phase De Baixa Resistência Mecânica Laminado a Frio

A Simple Method for Prediction of Shelf Life of Bake Hardening Steels

Relationship Between Bake Hardening, Snoek-Köster and Dislocation-Enhanced Snoek Peaks in Coarse Grained Low Carbon Steel

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