PSI - Issue 16

Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2018) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2018) 000 – 000

www.elsevier.com/locate/procedia

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 16 (2019) 113–120

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the 6th International Conference “Fracture Mechanics of Materials and Structural Integrity” organizers. © 201 9 The Authors. Published by Elsevier B.V. Peer- review under responsibility of the 6th International Conference “Fracture Mechanics of Materials and Structural Integrity” organizers. The presented work is dedicated t evaluation of strain and fatigue behaviour of th ferrite-pearlite low-alloyed pipeline steels u der known hydrogen once tration in a bulk of met l. Tensile test r sults have shown on the existence of some characteristic value of the hydrogen concentration C H at which the m chanism of hydr gen influe ce changes, namely: below this value the enha ced plasticity (decreasing of the yield stress value) takes place and above – the hydrogen embrittlement occurs. The ambiguous r lationship between fatigue cra k growth rate nd hydrogen concentration C H in the bulk of steels under their cyclic lo ding in hydrogen-contained environments has been found. There is a certain C H value at which the crack growth istance of steel increases and the diagram of fatigue crack growth rate shifts t higher values of stress intensity fact r. The generalised diagram of hydrogen concentration effect on strength behaviour of low-alloyed ferrite-pearlite pipeline steels is presented and discussed with the aim of evaluation of different mechanisms of hydrogen effect, conditions of their realization and possible co existence. © 201 9 The Authors. Published by Elsevier B.V. Peer- review under responsibility of the 6th International Conference “Fracture Mechanics of Materials and Structural Integrity” organizers. 6th International Conference “Fracture Mechanics of Materials and Structural Integrity” Specific effects of hydrogen concentration on resistance to fracture of ferrite-pearlitic pipeline steels Ihor Dmytrakh*, Andriy Syrotyuk, Rostyslav Leshchak Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine, 5 Naukova St., Lviv, 79060, Ukraine The presented work is dedicated to evaluation of strain and fatigue behaviour of the ferrite-pearlite low-alloyed pipeline steels under known hydrogen concentration in a bulk of metal. Tensile test results have shown on the existence of some characteristic value of the hydrogen concentration C H at which the mechanism of hydrogen influence changes, namely: below this value the enhanced plasticity (decreasing of the yield stress value) takes place and above – the hydrogen embrittlement occurs. The ambiguous relationship between fatigue crack growth rate and hydrogen concentration C H in the bulk of steels under their cyclic loading in hydrogen-contained environments has been found. There is a certain C H value at which the crack growth resistance of steel increases and the diagram of fatigue crack growth rate shifts to higher values of stress intensity factor. The generalised diagram of hydrogen concentration effect on strength behaviour of low-alloyed ferrite-pearlite pipeline steels is presented and discussed with the aim of evaluation of different mechanisms of hydrogen effect, conditions of their realization and possible co existence. 6th International Conference “Fracture Mechanics of Materials and Structural Integrity” Specific effects of hyd ogen concentratio on r sistance to fracture of ferrite-pearlitic pipeline steels Ihor Dmytrakh*, Andriy Syrotyuk, Rostyslav Leshchak Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine, 5 Naukova St., Lviv, 79060, Ukraine Abstract Abstract Keywords: Pipeline steel; hydrogen concentration; enhanced plasticity; hydrogen embrittlement.

Keywords: Pipeline steel; hydrogen concentration; enhanced plasticity; hydrogen embrittlement.

1. Introduction

1. Introduction

The application of hydrogen as an energy carrier and a working medium for the treatment of metal materials and alloys with an aim to improve their physico-mechanical and functional properties remains to be an urgent and The application of hydrogen as an energy carrier and a working medium for the treatment of metal materials and alloys with an aim to improve their physico-mechanical and functional properties remains to be an urgent and

* Corresponding author. Tel: +38-032-263-1400; fax: +38-032-264-9427. E-mail address: dmtr@ipm.lviv.ua

2452-3216 © 2019 The Author(s). Published by Elsevier B.V. Peer- review under responsibility of the 6th International Conference “Fracture Mechanics of Materials and Structural Integrity” organizers 2452-3216 © 2019 The Author(s). Published by Elsevier B.V. Peer- review under responsibility of the 6th International Conference “Fracture Mechanics of Materials and Structural Integrity” organizers * Corresponding author. Tel: +38-032-263-1400; fax: +38-032-264-9427. E-mail address: dmtr@ipm.lviv. a

2452-3216  2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the 6th International Conference “Fracture Mechanics of Materials and Structural Integrity” organizers. 10.1016/j.prostr.2019.07.029