{"id":{"repo_id":"brazil-uerj","oai_identifier":"oai:pantheon.ufrj.br:11422/8303"},"canonical_url":"https://search.dev.ndltd.org/etd/brazil-uerj/oai:pantheon.ufrj.br:11422/8303","repository":{"repo_id":"brazil-uerj","name":"Brazil UERJ","base_url":"https://pantheon.ufrj.br/oai/request"},"display":{"title":"Caracterização microestrutural em função da temperatura de serviço de tubos de aços HP-Modificados ao Nb e Ti envelhecidos em fornos de reforma a vapor","abstract":"Hydrogen is produced in reforming furnaces inside tubes, which are currently manufactured with HP-Nb and HP-NbTi steels. The service temperature of these tubes causes different degrees of metallurgical aging along their lengths. The purpose of the present work is to characterize the aging of these steels at different temperatures, taking into account the effects ofNb and Ti additions, to establish an aging classification criterion for these alloys. For this, four deactivated reforming tubes were analyzed, presenting compositionswith low Nb or high Nb and with or without micro additions of Ti. It was verified that the aging stage classification criterion for HP steels can be based on the one used for HK steels, considering, however, three factors: NbC \"Chinese script\" morphology in stage I, except for those steels with Ti or Zr; secondary precipitation in the aging stages II and III as a function of Cr/Nb ratio; and a more uniform distribution of secondary precipitation for steels with high Nb in the absence of Ti in aging stage IV.","abstract_html":"Hydrogen is produced in reforming furnaces inside tubes, which are currently manufactured with HP-Nb and HP-NbTi steels. The service temperature of these tubes causes different degrees of metallurgical aging along their lengths. The purpose of the present work is to characterize the aging of these steels at different temperatures, taking into account the effects ofNb and Ti additions, to establish an aging classification criterion for these alloys. For this, four deactivated reforming tubes were analyzed, presenting compositionswith low Nb or high Nb and with or without micro additions of Ti. It was verified that the aging stage classification criterion for HP steels can be based on the one used for HK steels, considering, however, three factors: NbC "Chinese script" morphology in stage I, except for those steels with Ti or Zr; secondary precipitation in the aging stages II and III as a function of Cr/Nb ratio; and a more uniform distribution of secondary precipitation for steels with high Nb in the absence of Ti in aging stage IV.","abstract_has_math":false,"creators":["Queiroz, Fábio dos Santos."],"institution":"Universidade Federal do Rio de Janeiro","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Almeida, Luiz Henrique de"],"committee_chairs":[],"committee_members":[],"year":2017,"date_issued":"2017-06","date_published":"2017-06","updated_at":"2026-07-24T01:16:29Z","subjects":["Planejamento Energético","Aços HP","Tubo de forno de reforma"],"languages":["por"],"rights":["Acesso Aberto"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/11422/8303","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Almeida, Luiz Henrique de"]},{"key":"dc:creator","label":"Author","values":["Queiroz, Fábio dos Santos."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2019-06-05T15:41:57Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2026-05-16T03:05:44Z"]},{"key":"dc:date.issued","label":"Date","values":["2017-06"]},{"key":"dc:publisher","label":"Institution","values":["Universidade Federal do Rio de Janeiro"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Instituto Alberto Luiz Coimbra de Pós-Graduação e Pesquisa de Engenharia"]},{"key":"dc:type","label":"Dc Type","values":["Dissertação"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Planejamento Energético","Aços HP","Tubo de forno de reforma"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["por"]},{"key":"dc:rights","label":"Dc Rights","values":["Acesso Aberto"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/11422/8303"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Hydrogen is produced in reforming furnaces inside tubes, which are currently manufactured with HP-Nb and HP-NbTi steels. The service temperature of these tubes causes different degrees of metallurgical aging along their lengths. The purpose of the present work is to characterize the aging of these steels at different temperatures, taking into account the effects ofNb and Ti additions, to establish an aging classification criterion for these alloys. For this, four deactivated reforming tubes were analyzed, presenting compositionswith low Nb or high Nb and with or without micro additions of Ti. It was verified that the aging stage classification criterion for HP steels can be based on the one used for HK steels, considering, however, three factors: NbC \"Chinese script\" morphology in stage I, except for those steels with Ti or Zr; secondary precipitation in the aging stages II and III as a function of Cr/Nb ratio; and a more uniform distribution of secondary precipitation for steels with high Nb in the absence of Ti in aging stage IV."]},{"key":"dc:title","label":"Title","values":["Caracterização microestrutural em função da temperatura de serviço de tubos de aços HP-Modificados ao Nb e Ti envelhecidos em fornos de reforma a vapor"]}]}],"canonical_facts":{"dc:contributor.advisor":["Almeida, Luiz Henrique de"],"dc:creator":["Queiroz, Fábio dos Santos."],"dc:date.accessioned":["2019-06-05T15:41:57Z"],"dc:date.available":["2026-05-16T03:05:44Z"],"dc:date.issued":["2017-06"],"dc:description.abstract":["Hydrogen is produced in reforming furnaces inside tubes, which are currently manufactured with HP-Nb and HP-NbTi steels. The service temperature of these tubes causes different degrees of metallurgical aging along their lengths. The purpose of the present work is to characterize the aging of these steels at different temperatures, taking into account the effects ofNb and Ti additions, to establish an aging classification criterion for these alloys. For this, four deactivated reforming tubes were analyzed, presenting compositionswith low Nb or high Nb and with or without micro additions of Ti. It was verified that the aging stage classification criterion for HP steels can be based on the one used for HK steels, considering, however, three factors: NbC \"Chinese script\" morphology in stage I, except for those steels with Ti or Zr; secondary precipitation in the aging stages II and III as a function of Cr/Nb ratio; and a more uniform distribution of secondary precipitation for steels with high Nb in the absence of Ti in aging stage IV."],"dc:identifier.uri":["http://hdl.handle.net/11422/8303"],"dc:language":["por"],"dc:publisher":["Universidade Federal do Rio de Janeiro"],"dc:publisher.department":["Instituto Alberto Luiz Coimbra de Pós-Graduação e Pesquisa de Engenharia"],"dc:rights":["Acesso Aberto"],"dc:subject":["Planejamento Energético","Aços HP","Tubo de forno de reforma"],"dc:title":["Caracterização microestrutural em função da temperatura de serviço de tubos de aços HP-Modificados ao Nb e Ti envelhecidos em fornos de reforma a vapor"],"dc:type":["Dissertação"]},"updated_at":"2026-07-24T01:16:29Z"}