Microstructure in unbent and as-hot bent segments of thick-walled P92 steel pipe

0450106 - ÚFM 2016 RIV CH eng C - Conference Paper (international conference)
Král, Petr - Sklenička, Václav - Kuchařová, Květa - Kvapilová, Marie - Svobodová, M. - Horváth, L.
Microstructure in unbent and as-hot bent segments of thick-walled P92 steel pipe.
Material Forming ESAFORM 2015. Zurich: Trans Tech Publications, 2015 - (Ofenheimer, A.; Poletti, C.; Schalk-Kitting, D.; Sommitsch, C.), s. 53-58. Key Engineering Materials, 651-653. ISBN 978-3-03835-471-0. ISSN 1013-9826.
[ESAFORM 2015 - International ESAFORM Conference on Material Forming /18./. Graz (AT), 15.04.2015-17.04.2015]
R&D Projects: GA TA ČR TA02010260
Institutional support: RVO:68081723
Keywords : hot bending * P92 steel pipe * creep behaviour * microstructure * EBSD
Subject RIV: JG - Metallurgy

The microstructure of P92 steel pipe processed by hot bending was evaluated in order to characterize its influence on microstructure changes in extrados and intrados of bend. The straight pipes, with an outer diameter of 350 mm and wall thickness of 39 mm were normalized at 1050°C/60min/air and tempered at 740°C/140min/air. The thick-walled pipe was then hot bended at 920-960°C using bending rate 7 mm/min. The bends were normalized at 1050°C/60min/air and tempered at 775°C/140min/air after hot bending. The selected specimens, machined from different locations of pipe, were additionally underwent thermal ageing at 650°C to simulate microstructure degradation typical for long-term service conditions. Microstructure was investigated by SEM Tescan Lyra 3 equipped with NordlysNano EBSD detector and by TEM. The results revealed that different processing history influenced distribution and size of secondary phases and caused changes in interboundary spacing both in the straight pipe and bends. It was found that microstructure changes induced during hot bending and subsequent post bending heat treatment caused deterioration in creep properties of bends in comparison with those of straight pipe.
Permanent Link: http://hdl.handle.net/11104/0251561