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Kander L.,Material and Metallurgical Research Ltd. | Stejskalova S.,Material and Metallurgical Research Ltd. | Cizek P.,Material and Metallurgical Research Ltd.
METAL 2016 - 25th Anniversary International Conference on Metallurgy and Materials, Conference Proceedings | Year: 2016

The paper deals with the change of the structure and mechanical properties of the austenitic steels after the exposure at the critical temperature. The effect of the bend radius of tubes on the mechanical properties and the structure was studied. The effect of solution annealing was studied too. The grades TP347 HFG, Super 304H and HR3C were chosen in the study. The bend radii R60, R80 and R100 were on the matter. The mechanical properties were studied using small punch test and miniaturized tensile tests. From the results can be concluded that the mechanical properties and the structure have been influenced due to one year exposure at the working temperature significantly. Various amounts of σ-phase were found in the pulled part of the bend side of the tubes even after only thermal exposure without any loading.

Hurst R.C.,University of Swansea | Matocha K.,Material and Metallurgical Research Ltd.
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2015

The underlying purpose of this paper is to evaluate whether the CEN CWA 15627 "Small Punch Test Method for Metallic Materials" first published in 2006 has indeed succeeded in providing a stimulus for a wider implementation of the small punch test technique in industrial applications throughout Europe and indeed worldwide. A wealth of research progress has been apparent, as strongly evidenced in three dedicated SSTT (Small Specimen Testing Techniques) conferences held in Europe over the last five years, but also in the wider literature. In particular it is important to mention the recent publication of a Japanese standard and the announcement of parallel progress in China. The present paper concentrates on progress within Europe from the launch of the Code to the present day. In particular attention is focused on the need for industrial acceptance of the test methodology and methods for evaluating the results. Some scepticism still seems to prevail within sectors of the conventional power generation industry, an industry which can potentially benefit most from successful remanent lifetime extension tools of which small punch testing can be considered as a prime candidate. In spite of this, it is demonstrated that a major proportion of the Small Punch testing research of the last decade has been carried out on power plant steels. Meanwhile it is shown that there is evidence that the original remit of the methodology in assessing the integrity of irradiated nuclear plant remains active, new interest is developing for aerospace and next generation nuclear applications enhancing further the credibility of the Code. Copyright © 2015 by ASME.

Hermanova S.,ViTKOVICE POWER ENGINEERING a.s. | Dobrovodska L.,ViTKOVICE POWER ENGINEERING a.s. | Kander L.,Material and Metallurgical Research Ltd.
METAL 2013 - 22nd International Conference on Metallurgy and Materials, Conference Proceedings | Year: 2013

This paper focuses on evaluation of the plastic deformation effect after the cold bending process for new austenitic materials Super304H, HR3C and Tp347HFG designed for supercritical conditions. The qualification tests were carried out on bends in two dimensions of tubes which are the most common sizes used in superheaters for supercritical power plant boiler. The bends were produced by the method of cold bending with mandrel bending technology and without mandrel on several bending radii in order to obtain information about the structure and behavior of materials at various stages of deformation. To obtain reliable information, tensile test, hardness test and metallographic examination were used on material from straight tubes of the bends, drawn and compressed parts which are presented in this article. We acquire new information about the stress-strain behavior of advanced structural materials thanks to the realization this experimental program. We also obtained the input data for subsequent long-term corrosion tests and thermal degradation tests and correlation relations for the determination of the strength properties of steels studied by SPT. The tests are carried out under the grand project of the Technology Agency TA01010181 with the name Bending-tubes-technology for superheaters and inter-superheaterstubes for the progressive boiler construction which VÍTKOVICE POWER ENGINEERING a.s. researches in cooperation with UJP a.s. and SVÚM a.s. © 2013 TANGER Ltd., Ostrava.

Greger M.,VSB - Technical University of Ostrava | Kander L.,Material and Metallurgical Research Ltd.
METAL 2013 - 22nd International Conference on Metallurgy and Materials, Conference Proceedings | Year: 2013

Cold and hot Equal-Channel Angular Pressing (ECAP) is an effective method to refine metallic grains. In this paper effect of ECAP technology on structure and mechanical properties including low cycle fatigue of austenitic stainless steel AISI 316 were studied. Effect of hot ECAP at 280 oC on grains refinement was investigated. Testing results show that the refinement of grains can not be infinitely increased with increasing of ECAP passes or total strain. Microstructure evolution was observed by transmission electron microscopy (TEM). Microstructure analysis shows that deformation led to the formation of grain subdivision inside deformation bands and the onset of new grains formation even after 2 ECAP passes. The deformation up to 6 passes lead to the formation of recrystallized grains of the order of 100-250 nm size. Based on experimental results we can conclude that mechanical properties after ECAP show saturation at approx. 6 passes that corresponds equivalent strain ~1.0 per pass (equivalent strain varied from 1.0 to 6). At presented condition of ECAP (isothermal ECAP condition at +280 °C) we can concluded that optimum number of passes for steel under investigation are between 4 and 6 passes. Effect of ECAP technology on low-cycle fatigue properties have been studied also, comparison of Manson-Coffin and cyclic stress-strain curves with virgin state of the steel under investigation have been carried out. © 2013 TANGER Ltd., Ostrava..

Matocha K.,Material and Metallurgical Research Ltd.
Journal of Pressure Vessel Technology, Transactions of the ASME | Year: 2011

This paper describes the structure of the Standard Technical Documentation of the Association of Mechanical Engineers of Czech Republic, Sec. II, "Material Properties for Equipments and Pipings of Water moderated, Water Cooled Energy Reactor (WWER) Nuclear Power Plants (NPPs)." It provides instructions for selection and qualification of parent materials used for manufacture, repair, reconstruction, or replacement of selected equipments of WWER NPP, and specifies requirements for mechanical characteristics and physical properties. © 2011 American Society of Mechanical Engineers.

Kubon Z.,Material and Metallurgical Research Ltd.
Key Engineering Materials | Year: 2015

Current trend in increasing steam parameters in ultra-supercritical (USC) boilers requires new materials not only for membrane walls, headers and pipelines but also for superheater and reheater tubes. Newly developed austenitic steels Super304H. TP347HFG and HR3C exhibit superior resistance in steam thanks to their fine-grained microstructure, especially in case of Super304H and TP347HFG. The paper presents the results of verification of properties of these steels tubes including creep resistance of the base metal and welded joints, which show promising level of long-term creep strength of the base metal and weld joints and these results are supplemented by some new knowledge about the development of the microstructure of these steels, especially sigma phase appearance. © (2015) Trans Tech Publications, Switzerland.

Pekarova L.,Material and Metallurgical Research Ltd. | Kubon Z.,Material and Metallurgical Research Ltd.
Key Engineering Materials | Year: 2015

Routine non-destructive examination of the steam pipe elbow after more than 240 000 hours of operation at elevated temperature revealed the extensive creep damage on the outer surface of the pipe elbow. Complex metallographic analysis made in this area confirmed creep damage as well as the non-uniform nature of the cavitation. The density of cavities continuously decreased from the outer pipe surface towards the inner surface, but also its density rapidly waned beyond the damaged area in both directions, along the circumference as well as the length of the elbow. The actual extent of the material degradation was then evaluated by testing of mechanical properties, Charpy-V and fracture toughness testing and the results were used in calculation of the residual life of the pipe elbow. It was shown that although the creep damage was perhaps one of the worst detected in Czech Republic, the cracks in the pipe elbow would spread by the stable growth until the half of the pipe wall thickness. This result thus confirms the possibility of creep life extension far beyond the limit criteria used so far. © (2015) Trans Tech Publications, Switzerland.

Matocha K.,Material and Metallurgical Research Ltd.
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2012

The assessment of the residual lifetime of critical components of industrial plants requires the knowledge of mechanical properties prior to operation, respecting all technological operations realized throughout the manufacture of the component, and the knowledge of mechanical properties after actual time of operation (actual mechanical properties). Small Punch (SP) test technique enables measurement of the realistic material properties at the critical locations in the component both prior and after long-term operation. The paper shows the examples of the sampling of testing material from the critical components of the industrial plants and the procedures for determination of tensile and fracture characteristics by SP tests at ambient and low temperatures. The special attention is devoted to the test specimen orientation for determination of SP fracture energy ESP. Copyright © 2012 by ASME.

Matocha K.,Material and Metallurgical Research Ltd.
ASTM Special Technical Publication | Year: 2015

The present paper summarizes the procedures described in CWA 15627 [CEN Workshop Agreement, "Small Punch Test Method for Metallic Materials," CWA 15627:2007 D/E/F, European Committee for Standardization, Brussels, Belgium, 2007] for determination of tensile and fracture characteristics of metallic materials from the results of small-punch tests together with the corrections of this document proposed in the frame of its prospective conversion into a European standard. The corrections were proposed on the basis of the experiences obtained in the period 2007-2012 at Material and Metallurgical Research, Ltd. (Ostrava, Czech Republic). Copyright © 2015 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.

Matocha K.,Material and Metallurgical Research Ltd.
Procedia Engineering | Year: 2014

The paper summarizes the experience gained with the evaluation of the transition behaviour of steels with BCC lattice from the results of penetration tests. Determination of fracture appearance transition temperature FATT from the results of penetration tests is currently performed only on empirical correlations between FATT and transition temperature TSP determined of the penetration tests in the temperature range from -193 ° C to +23°C. Factors that may significantly affect the transition temperature TSP and thus empirical correlations FATT-TSP are discussed. © 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.

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