Effect of finishing rolling temperature on fire resistance and dynamic strain aging behavior of a structural steel

Calado, Welbert Ribeiro; Santos, Odair José dos; Castro, Cynthia Serra Batista; Barbosa, Ricardo Rodrigues; Gonzalez, Berenice Mendonça

doi:10.1007/s10853-008-2640-z

Cited by 10 publications

(6 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…For the rest of the selected conditions, the tensile strength decreases monotonously with the temperature of the tensile test in the 293 K to 623 K (20°C to 350°C) range. This is in line with the behavior observed for different steels grades, [39][40][41] particularly when the addition of strong nitride forming elements like B [39] or V [40] removes nitrogen from the solid solution. Transmission electron microscopy has revealed Nb(C,N) interphase precipitates and AlN particles at dislocations in steel A processed according to the S1 sequence and coiled at 1023 K (750°C).…”

Section: Ys/tssupporting

confidence: 88%

“…In C-Mn steels, the magnitude of this deviation depends on the amount of free N. Nevertheless, the peak tensile strength for S1 and coiling at 873 K (600°C) is relatively low when compared with the one obtained for C-Mn-Mo-Nb steels of nitrogen content similar to steel A. [41] This could indicate that the amount of N in solution is low even for S1 and coiling at 873 K (600°C) sequence. Alternatively, it is known that the precipitates finely dispersed in the matrix are effective sinks for free interstitial elements.…”

Section: Ys/tsmentioning

confidence: 88%

See 1 more Smart Citation

Precipitation of Nb in Ferrite After Austenite Conditioning. Part II: Strengthening Contribution in High-Strength Low-Alloy (HSLA) Steels

Altuna

Iza-Mendia

Gutiérrez

2012

Metall Mater Trans A

View full text Add to dashboard Cite

. ALTUNA, AMAIA IZA-MENDIA, and I. GUTIÉ RREZ Often, Nb contributes to the strength of a microalloyed steel beyond the expected level because of the grain size strengthening resulting from thermomechanical processing. Two different mechanisms are behind this phenomenon, and both of them have to do with the amount of Nb remaining in solution after hot rolling. The first of them is the increase of the hardenability of the steel as a result of Nb, and the second one is the fine precipitation of NbC in ferrite. Three Nb microalloyed steels were thermomechanically processed in the laboratory and coiled at different temperatures to investigate the effect of Nb content on the tensile properties. The extra strength was linearly related to the Nb remaining in solution after the hot working. The maximum contribution from Nb was reached for a coiling temperature of 873 K (600°C).

show abstract

Section: Ys/tssupporting

confidence: 88%

Section: Ys/tsmentioning

confidence: 88%

Precipitation of Nb in Ferrite After Austenite Conditioning. Part II: Strengthening Contribution in High-Strength Low-Alloy (HSLA) Steels

Altuna

Iza-Mendia

Gutiérrez

2012

Metall Mater Trans A

View full text Add to dashboard Cite

show abstract

“…These values suggest that the mechanism responsible for dynamic strain aging in dual phase steel is the locking of dislocations by carbon atoms in ferrite and that the formation of clusters and/or transition carbides and carbide precipitation in martensite do not interfere with the dynamic strain process [17]. The phenomenological aspects of dynamic strain aging presented in this work, i.e., the presence of the PLC effect in the stress-strain curves; the maximum in the variation of flow stress, tensile stress and work hardening exponent with temperature; the minimum in the variation of uniform strain with temperature; as well as the shift of these maxima and minima to higher temperatures, indicate that the dual phase steels behave mostly in the same manner as steels of low carbon steels, alloyed or not, and perlitic steels, regarding dynamic strain aging [18].…”

Section: Fig9 Hardness Distribution Of 70b Steelmentioning

confidence: 95%

Effect of Hot Forging and Boron Content on the Mechanical Properties of Dual Phase Steel

Farahat

Ayyad

El‐Desouky

et al. 2013

International Conference on Aerospace Sciences and Aviation Tec

View full text Add to dashboard Cite

Carbon steel is widely used in different applications such as automotive industry. Boron is used as micro-alloying element to enhance the mechanical properties of carbon steel. The objective of the present work is to study the effect of boron on mechanical properties of dual phase steels. Dual phase (DP) steel is used in the underbody suspension for automotives. The material used in the present study was a carbon alloy steel (0.29 Cwt %) with different boron contents 0.0003 and 0.007wt %. The steels were cast using an open air induction furnace. The molten steel had the shape of Y-blocks. The parts of Y-blocks of alloys 0.0003B and 0.007B steels were heated up to 1200ºC and then hot forged producing bars. After hot forging, the bars were subjected to air cooling. In the hardening process, the different alloys (0.0003B, 0.007B) were heated up to the intercritical annealing temperatures (between Ac1 and Ac3) for 15 minutes and then water quenched. The resultant microstructures after quenching process were observed as ferrite plus islands of martensite. After that, tempering was done at 300°C, 400°C and 500°C for different interval times. The experimental results revealed the mechanical properties of the selective alloys were significantly changed by boron content and tempering treatment. By increasing the boron content, hardness gradually increased with small effect on ductility of alloys. By increasing the tempering time and temperature, hardness was gradually decreased while ductility was improved. Compression testing was carried out to determine the compression strength and work-hardening coefficient. The studied steel presented typical manifestations related to dynamic strain aging: serrated flow (the Portevin-Le Chatelier effect).

show abstract

“…Se a tensão de cisalhamento na deslocação tem intensidade constante, a deslocação se move a uma velocidade maior nas regiões cujo campo de tensões é de baixa intensidade e com menor velocidade naquela região cujo campo de tensões é de elevada intensidade [1]. Havendo aumento ou diminuição da velocidade das deslocações em relação à média, os efeitos do envelhecimento dinâmico, gerados pela tensão de atrito, mencionada anteriormente, são deslocados para maiores ou menores temperaturas, respectivamente [4][5][6][7]. Dessa forma, o autor [1] explica o acúmulo de deslocações em determinadas regiões da amostra, submetida aos efeitos do envelhecimento dinâmico, ou seja, naquelas regiões nas quais o campo de tensões internas apresenta intensidade elevada, pois nesse caso a elevação da tensão de atrito aplicada pelas atmosferas de Cottrell reduz ainda mais a velocidade das deslocações.…”

Section: Introductionunclassified

“…Segundo Queiroz et al [4], o envelhecimento dinâmico ocorre unicamente pelo ancoramento das deslocações na ferrita por átomos de carbono, uma vez que nem os aspectos fenomenológicos, nem as energias de ativação aparentes obtidas indicam que ocorre formação de clusters e/ou carbonetos de transição ou precipitação na martensita durante a deformação nas temperaturas em que foram observados os efeitos de envelhecimento dinâmico. Dessa forma, os mecanismos controladores do envelhecimento dinâmico em aços ferríticos, ligados ou não [5,6,19], em aços com estrutura completamente perlítica [7] e em aços Dual Phase [4] já são conhecidos, mas não há na literatura referências de análises de subestruturas de deslocações e verificação da existência de precipitados nos constituintes do aço deformado em condições de envelhecimento dinâmico. Assim sendo, o objetivo deste trabalho é a caracterização da subestrutura de deslocações de um aço Dual Phase em temperaturas nas quais ocorre o envelhecimento dinâmico.…”

Section: Introductionunclassified

Evolução Da Subestrutura De Deslocações Em Um Aço Dual Phase Sujeito a Condições De Envelhecimento Dinâmico

Queiroz¹,

Gonzalez²,

Santos³

2014

ABM Proceedings

Self Cite

View full text Add to dashboard Cite

ResumoAmostras de um aço Dual Phase, não deformadas e deformadas à temperatura ambiente e em condições de envelhecimento dinâmico foram examinadas por microscopia eletrônica de transmissão, visando analisar modificações na subestrutura de deslocações na faixa de temperaturas em que ocorre o fenômeno. Observaram-se mudanças significativas no padrão de distribuição das deslocações que evoluiu de uma distribuição uniforme, no material deformado à temperatura ambiente, para uma distribuição em forma de linhas alongadas a 200°C e 300°C, culminando em uma subestrutura complexa com elevada densidade de deslocações a 350°C. A 400°C, a distribuição uniforme foi novamente verificada. As imagens obtidas não indicaram a ocorrência de formação de carbonetos de transição ou precipitação na martensita durante a deformação nas temperaturas em que foram observados os efeitos de envelhecimento dinâmico. Palavras-chave: Envelhecimento dinâmico; Aços dual phase; Subestruturas de deslocações. THE DEVELOPMENT OF DISLOCATION SUBSTRUCTURE IN DUAL PHASE STEELS SUBJECTED TO DYNAMIC STRAIN AGEING AbstractTransmission electron microscopy was used to examine samples of deformed and undeformed dual phase steel under conditions of dynamic strain ageing. The objective was to analyse the changes in dislocation substructure within the temperature range at which this phenomenon occurs. Significant changes were observed in the dislocation distribution pattern that developed from a uniform distribution, in material deformed at room temperature, to a distribution in the form of elongated lines at 200°C and 300°C, culminating in a complex substructure with a high dislocation density at 350°C. At 400°C, a uniform distribution was once again observed. The images obtained did not indicate the formation of transition carbides or precipitation in martensite during deformation at the temperatures at which dynamic strain ageing was observed.

show abstract

Effect of finishing rolling temperature on fire resistance and dynamic strain aging behavior of a structural steel

Cited by 10 publications

References 10 publications

Precipitation of Nb in Ferrite After Austenite Conditioning. Part II: Strengthening Contribution in High-Strength Low-Alloy (HSLA) Steels

Precipitation of Nb in Ferrite After Austenite Conditioning. Part II: Strengthening Contribution in High-Strength Low-Alloy (HSLA) Steels

Effect of Hot Forging and Boron Content on the Mechanical Properties of Dual Phase Steel

Evolução Da Subestrutura De Deslocações Em Um Aço Dual Phase Sujeito a Condições De Envelhecimento Dinâmico

Contact Info

Product

Resources

About