Influence of welding stresses on relaxation cracking during heat treatment of a creep-resistant 13CrMoV steel
- Over the past years economic and environmental considerations have led to a markedly increased demand for efficiency and flexibility in petrochemical plants. The operational temperatures and pressures required today can only be achieved by using new creep-resistant grades of steel. The modified 13CrMoV9-10 vanadium steel shows a good resistance against creep and compressed hydrogen and has been in use for the construction of petrochemical reactors since the mid-1990s. Nevertheless, processing of this type of steel requires extreme care during the welding procedure. This is due to its low toughness and high strength in the welded state when not post weld heat treated combined with increased susceptibility to cracking during stress relaxation. Previous research into crack formation in creep-resistant steels has largely focused on thermal and metallurgical factors; however, little knowledge has been gathered regarding the influence of the welding procedure on crack formation during postOver the past years economic and environmental considerations have led to a markedly increased demand for efficiency and flexibility in petrochemical plants. The operational temperatures and pressures required today can only be achieved by using new creep-resistant grades of steel. The modified 13CrMoV9-10 vanadium steel shows a good resistance against creep and compressed hydrogen and has been in use for the construction of petrochemical reactors since the mid-1990s. Nevertheless, processing of this type of steel requires extreme care during the welding procedure. This is due to its low toughness and high strength in the welded state when not post weld heat treated combined with increased susceptibility to cracking during stress relaxation. Previous research into crack formation in creep-resistant steels has largely focused on thermal and metallurgical factors; however, little knowledge has been gathered regarding the influence of the welding procedure on crack formation during post weld heat treatment considering real-life manufacturing conditions. In this work, the influence of heat control on the mechanical properties has been investigated by simulating the real-life manufacturing conditions prevailing during the construction of petrochemical reactors using a special 3-D testing facility. The stresses resulting from preheating, welding, dehydrogenation heat treatment and the final post weld heat treatment were measured during experiments under varied heat control. In all experiments stress relief cracks formed during post weld heat treatment could be observed. The total crack lengths correlated with the stresses due to welding. The application of a special acoustic emission analysis indicated that the cracks formed during post weld heat treatment in a temperature range between 300 °C and 500 °C. In comparison to small scale samples welded without additional shrinkage restraint, the toughness of the restrained welds was significantly decreased. SEM and TEM analyses of all samples revealed accelerated aging due to early precipitation of special carbides during post weld heat treatment under component relevant restraint.…
Autor*innen: | Thomas Lausch |
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Koautor*innen: | Arne Kromm, Dirk Schroepfer, Thomas Kannengießer, Thomas Schaupp |
Dokumenttyp: | Vortrag |
Veröffentlichungsform: | Präsentation |
Sprache: | Englisch |
Jahr der Erstveröffentlichung: | 2019 |
Organisationseinheit der BAM: | 9 Komponentensicherheit |
9 Komponentensicherheit / 9.2 Versuchsanlagen und Prüftechnik | |
9 Komponentensicherheit / 9.4 Integrität von Schweißverbindungen | |
DDC-Klassifikation: | Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten |
Freie Schlagwörter: | Creep-resistant steel; Post weld heat treatment; Stress relief cracking; Welding |
Themenfelder/Aktivitätsfelder der BAM: | Material |
Material / Degradation von Werkstoffen | |
Veranstaltung: | IIW Intermediate Meeting: Commission II-A |
Veranstaltungsort: | Miami, FL, USA |
Beginndatum der Veranstaltung: | 12.03.2019 |
Enddatum der Veranstaltung: | 14.03.2019 |
Verfügbarkeit des Dokuments: | Datei im Netzwerk der BAM verfügbar ("Closed Access") |
Datum der Freischaltung: | 22.03.2019 |
Referierte Publikation: | Nein |
Eingeladener Vortrag: | Nein |