HIGH - TEMPERATURE CREEP BEHAVIOUR OF CAST COBALT-BASE SUPERALLOYS

0497285 - ÚFM 2019 RIV CZ eng C - Conference Paper (international conference)
Dvořák, Jiří - Král, Petr - Kvapilová, Marie - Hrbáček, Karel - Sklenička, Václav
HIGH - TEMPERATURE CREEP BEHAVIOUR OF CAST COBALT-BASE SUPERALLOYS.
Metal 2018 - 27th International conference on metallurgy and materials, Conference Proceedings. Ostrava: TANGER Ltd, 2018, s. 530-535. ISBN 978-80-87294-84-0.
[Metal 2018 - International conference on metallurgy and materials /27./. Brno (CZ), 23.05.2018-25.05.2018]
R&D Projects: GA MPO FV10699; GA MŠMT LM2015069; GA MŠMT(CZ) ED1.1.00/02.0068
Institutional support: RVO:68081723
Keywords : Co-based superalloys * creep tests * microstructure evolution * carbide precipitation * damage process
OECD category: Materials engineering

Two cast and heat-treated NbC and TaC – strengthened cobalt superalloys have been developed for a precision casting of spinner discs for glass wool industry. In this work constant load creep tests in tension were carried out in argon atmosphere at three testing temperature 900, 950 and 1000 °C and at the initial applied stresses ranged from 40 to 200 MPa. All the tests were continued until the final fracture. The results of creep testing were combined with microstructural and fractographic examinations by means of light and scanning electron microscopy. A mutual comparison of creep characteristics of the investigated superalloys under comparable creep loading conditions showed that NbC-strengthened superalloy exhibited longer creep life than TaC-strengthened one. Further, it was found that carbide precipitation is the primary strengthening mechanism in both cobalt-base superalloys under investigation and the amount, morphology
and type of carbides have the decisive effect on the creep properties including creep damage and fracture processes. By contrast, NbC-superalloy exhibited a more brittle character of creep fracture mode than TaCstrengthened superalloy. This study was initiated to investigate in more details creep deformation processes and the effect of the creep microstructure and damage evolution on both investigated superalloys. The different behaviour and properties of studied superalloys were explained based on the received results of this study.
Permanent Link: http://hdl.handle.net/11104/0291961