PSI - Issue 19

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Available online at www.sciencedirect.com Structural I tegrity Procedia 00 (2019) 000 – 000 Structural Integrity Procedia 00 (2019) 000 – 000

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Procedia Structural Integrity 19 (2019) 231–237

Fatigue Design 2019 Thermo-Mechanical Fatigue of a CrMo Steel Applicable to Steam Turbine Shafts Martin Nesládek a * , Milan Růžička a , Maxim Lutovinov a, Jiří Kuželka a , Radek Procházka b , Martin Rund b , Petr Měšťánek c a Czech Technical University in Prague, Faculty of Mechanical Engineering, Technická 4, 166 07 Prague 6, Czech Republic Fatigue Design 2019 Thermo-Mechanical Fatigue of a CrMo Steel Applicable to Steam Turbine Shafts Martin Nesládek a * , Milan Růžička a , Maxim Lutovinov a, Jiří Kuželka a , Radek Procházka b , Martin Rund b , Petr Měšťánek c a Czech Technical University in Prague, Faculty of Mechanical Engineering, Technická 4, 166 07 Prague 6, Czech Republic b COMTES FHT a.s., Průmyslová 995, 334 4 Dobřany, z li c Doosan Škoda Power s.r.o., Tylova 1/57, 301 28 Plzeň, Czech Republic b COMTES FHT a.s., Průmyslová 995, 334 41 Dobřany, Czech Republic c Doosan Škoda Power s.r.o., Tylova 1/57, 301 28 Plzeň, Czech Republic The paper is an overview of the work conducted in order to investigate thermo-mechanical fatigue (TMF) performance of a CrMo steel applicable to steam turbine shaft design. Uniaxial TMF tests of tubular specimens under various temperature ranges and phase shifts were carried out. Damage Operator Approach (DOA) proposed by Nagode et al. (2009) was calibrated by low cycle fatigue experiments and its quality of prediction was verified by the TMF tests. The obtained results show that the DOA predicts the tests with higher range of temperatures (100-600 °C) much better than those subjected to 450-600 °C. The method can distinguish well the effect of different mechanical-to-temperature phase shift. The paper is an overview of the work conducted in order to investigate thermo-mechanical fatigue (TMF) performance of a CrMo steel applicable to steam turbine shaft design. Uniaxial TMF tests of tubular specimens under various temperature ranges and phase shifts were carried out. Damage Operator Approach (DOA) proposed by Nagode et al. (2009) was calibrated by low cycle fatigue experiments and its quality of prediction was verified by the TMF tests. The obtained results show that the DOA predicts the tests with higher range of temperatures (100-600 °C) much better than those subjected to 450-600 °C. The method can distinguish well the effect of different mechanical-to-temperature phase shift. Abstract Abstract

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers.

Keywords: thermo-mechanical fatigue; steam turbine; damage operator approach; digital image correlation Keywords: thermo-mechanical fatigue; steam turbine; damage operator approach; digital image correlation

1. Introduction 1. Introduction

With increasing share of renewable energy sources in the electricity production (Eurostat, 2016) strict demands are placed on thermal power plants that have to cover the power fluctuations more frequently. Increasing number of gas and steam turbine (ST) start-ups and shutdowns, as well as requirements on faster ramping of operating conditions, has detrimental effect on the overall lifetime of ST components. In the ST design process, this situation has to be dealt by applying advanced prediction methodologies handling the thermo-mechanical fatigue mechanism. On the other hand, in the case of currently operating STs, regular inspection and maintenance schedule as well as technologies for turbine operation control have to be reconsidered or newly developed. Materials applicable to design of ST turbine components have to be subjected to testing under the loads representing real operating conditions as close as possible. Especially, materials for high-pressure (HP) and intermediate-pressure (IP) section With increasing share of renewable energy sources in the electricity production (Eurostat, 2016) strict demands are placed on thermal power plants that have to cover the po er fluctuations more frequently. Increasing number of gas and steam turbine (ST) start-ups and shutdowns, as well as requirements on faster ramping of operating conditions, has detrimental effect on the overall lifetime of ST components. In the ST design process, this situation has to be dealt by applying advanced prediction methodologies handling the thermo-mechanical fatigue mechanism. On the other hand, in the case of currently operating STs, regular inspection and maintenance schedule as well as technologies for turbine operation control have to be reconsidered or newly developed. Materials applicable to design of ST turbine components have to be subjected to testing under the loads representing real operating conditions as close as possible. Especially, materials for high-pressure (HP) and intermediate-pressure (IP) section

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers.

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. 10.1016/j.prostr.2019.12.025