Evolution of microstructure and precipitationstate during thermomechanical processing of a X80 microalloyed steel

A series of anisothermal hot torsion tests were carried out to simulate hot rolling on a high-strength low-carbon CMnNbMoTi microalloyed steel corresponding to an industrial X80 grade for pipeline construction. Mean Flow Stress was graphically represented against the inverse of temperature to charac...

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Detalles Bibliográficos
Autores: Gómez, Manuel, Valles, P., Medina, Sebastián F.
Tipo de recurso: artículo
Fecha de publicación:2011
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/56438
Acceso en línea:http://hdl.handle.net/10261/56438
Access Level:acceso abierto
Palabra clave:Transmission electron microscopy
Microalloyed steel
Pipeline
Thermomechanical processing
Acicular ferrite
Precipitation
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spelling Evolution of microstructure and precipitationstate during thermomechanical processing of a X80 microalloyed steelGómez, ManuelValles, P.Medina, Sebastián F.Transmission electron microscopyMicroalloyed steelPipelineThermomechanical processingAcicular ferritePrecipitationA series of anisothermal hot torsion tests were carried out to simulate hot rolling on a high-strength low-carbon CMnNbMoTi microalloyed steel corresponding to an industrial X80 grade for pipeline construction. Mean Flow Stress was graphically represented against the inverse of temperature to characterize the evolution of austenite microstructure during rolling, which was also studied by optical microscopy and SEM on samples quenched from several temperatures. On the other hand, particles precipitated at different temperatures during rolling were analyzed by means of TEM using the carbon extraction replica technique and their size distribution and mean size were determined, as well as their morphology, nature and chemical composition. The effect of rolling temperature and austenite strengthening obtained at the end of thermomechanicalprocessing on final microstructure and precipitationstate was studied. Austenite strengthening was characterized by means of the parameter known as accumulated stress (Δσ). It was found that ferrite grains are finer and more equiaxed when the austenite is more severely deformed during finishing (higher values of Δσ) but lower values of Δσ generate a higher density of acicular structures after cooling, which should improve the balance of mechanical properties. The increase in strength associated to acicular ferrite compared to polygonal ferrite is revealed by the higher values of Vickers microhardness measured on samples corresponding to low Δσ. On the other hand, (Ti, Nb)-rich carbonitrides can be found from reheating and their size keeps a constant value near 20–30 nm during thermomechanicalprocessing. A second population of much finer (Nb, Mo)-rich carbonitrides whose size is close to 5 nm forms from lower temperatures, near 1000 °C. The accomplishment of two different levels of Δσ at the end of hot rolling schedule does not seem to introduce major differences in precipitationstate before final cooling.Peer reviewedElsevier201220122011info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501http://hdl.handle.net/10261/56438reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Ingléshttp://dx.doi.org/10.1016/j.msea.2011.02.087info:eu-repo/semantics/openAccessoai:digital.csic.es:10261/564382026-05-22T06:33:51Z
dc.title.none.fl_str_mv Evolution of microstructure and precipitationstate during thermomechanical processing of a X80 microalloyed steel
title Evolution of microstructure and precipitationstate during thermomechanical processing of a X80 microalloyed steel
spellingShingle Evolution of microstructure and precipitationstate during thermomechanical processing of a X80 microalloyed steel
Gómez, Manuel
Transmission electron microscopy
Microalloyed steel
Pipeline
Thermomechanical processing
Acicular ferrite
Precipitation
title_short Evolution of microstructure and precipitationstate during thermomechanical processing of a X80 microalloyed steel
title_full Evolution of microstructure and precipitationstate during thermomechanical processing of a X80 microalloyed steel
title_fullStr Evolution of microstructure and precipitationstate during thermomechanical processing of a X80 microalloyed steel
title_full_unstemmed Evolution of microstructure and precipitationstate during thermomechanical processing of a X80 microalloyed steel
title_sort Evolution of microstructure and precipitationstate during thermomechanical processing of a X80 microalloyed steel
dc.creator.none.fl_str_mv Gómez, Manuel
Valles, P.
Medina, Sebastián F.
author Gómez, Manuel
author_facet Gómez, Manuel
Valles, P.
Medina, Sebastián F.
author_role author
author2 Valles, P.
Medina, Sebastián F.
author2_role author
author
dc.subject.none.fl_str_mv Transmission electron microscopy
Microalloyed steel
Pipeline
Thermomechanical processing
Acicular ferrite
Precipitation
topic Transmission electron microscopy
Microalloyed steel
Pipeline
Thermomechanical processing
Acicular ferrite
Precipitation
description A series of anisothermal hot torsion tests were carried out to simulate hot rolling on a high-strength low-carbon CMnNbMoTi microalloyed steel corresponding to an industrial X80 grade for pipeline construction. Mean Flow Stress was graphically represented against the inverse of temperature to characterize the evolution of austenite microstructure during rolling, which was also studied by optical microscopy and SEM on samples quenched from several temperatures. On the other hand, particles precipitated at different temperatures during rolling were analyzed by means of TEM using the carbon extraction replica technique and their size distribution and mean size were determined, as well as their morphology, nature and chemical composition. The effect of rolling temperature and austenite strengthening obtained at the end of thermomechanicalprocessing on final microstructure and precipitationstate was studied. Austenite strengthening was characterized by means of the parameter known as accumulated stress (Δσ). It was found that ferrite grains are finer and more equiaxed when the austenite is more severely deformed during finishing (higher values of Δσ) but lower values of Δσ generate a higher density of acicular structures after cooling, which should improve the balance of mechanical properties. The increase in strength associated to acicular ferrite compared to polygonal ferrite is revealed by the higher values of Vickers microhardness measured on samples corresponding to low Δσ. On the other hand, (Ti, Nb)-rich carbonitrides can be found from reheating and their size keeps a constant value near 20–30 nm during thermomechanicalprocessing. A second population of much finer (Nb, Mo)-rich carbonitrides whose size is close to 5 nm forms from lower temperatures, near 1000 °C. The accomplishment of two different levels of Δσ at the end of hot rolling schedule does not seem to introduce major differences in precipitationstate before final cooling.
publishDate 2011
dc.date.none.fl_str_mv 2011
2012
2012
dc.type.none.fl_str_mv info:eu-repo/semantics/article
http://purl.org/coar/resource_type/c_6501
format article
dc.identifier.none.fl_str_mv http://hdl.handle.net/10261/56438
url http://hdl.handle.net/10261/56438
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv http://dx.doi.org/10.1016/j.msea.2011.02.087
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.publisher.none.fl_str_mv Elsevier
publisher.none.fl_str_mv Elsevier
dc.source.none.fl_str_mv reponame:DIGITAL.CSIC. Repositorio Institucional del CSIC
instname:Consejo Superior de Investigaciones Científicas (CSIC)
instname_str Consejo Superior de Investigaciones Científicas (CSIC)
reponame_str DIGITAL.CSIC. Repositorio Institucional del CSIC
collection DIGITAL.CSIC. Repositorio Institucional del CSIC
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15,81155

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