Wyniki wyszukiwania - Biblioteka Nauki

1

A computational study of hydrogen embrittlement phenomena in an iron nickel based alloy

100%

Simonetti S. I. , Brizuela G. P. , Juan A.

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tom Vol. 27, No. 2

595--601

EN

The interaction between H atoms and a Fe50Ni50 alloy containing vacancies was studied. The energy of the system was calculated by the atom superposition and electron delocalization molecular orbital (ASED-MO) method. The electronic structure was studied using the concept of density of states (DOS) and crystal orbital overlap population (COOP) curves. The minimum energy position for the H atom in the vacancy region was found at 1.32 A from the vacancy centre. The changes in the electronic structure of Fe and Ni atoms near the vacancies were analyzed. The interactions mainly involve Fe and Ni metal 4s and 4p atomic orbitals, the most important being the contribution of Fe orbitals. Fe-Fe, Fe-Ni and Ni-Ni bonds weakened as new Fe-H ones were formed. The effect of H atoms is limited to its first neighbours. The detrimental effect of H atoms on the metallic bonds can be related to the mechanism for H embrittlement.

2

Case studies of steel and their welded joint failures caused by liquid metal embrittlement LME

75%

Bernasovský P. , Brziak P.

Przegląd Spawalnictwa

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2015

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tom R. 87, nr 2

37--40

EN

Liquid metal embrittlement (LME) is a phenomenon, where liquid (molten) metal is mostly intergranulary (but not only) penetrated into solid metal and causes its brit- tle fracture. The LME is usually related to low melting metals (zink, tin, cadmium), which are in the contact with higher molten ones (steels, Ni alloys). Cases of LME as a Cu penetration into pipeline welded joint of 15G2S steel, a hot temperature corrosion in the cement works shell plate made of AISI 310 stainless steel attacted by Ni3S2 (Ts = 644 °C) and a vanadium corrosion in the boiler vessel (10CrMo9-10 steel) due to V2O5 + Na2SO4 eutecticum (~600 °C) are concerned.

PL

Kruchość stali wywołana obecnością cieczy metalicznej (ang. LME – liquid metal embrittlement) zachodzi podczas oddziaływania i w konsekwencji penetrowania granic ziaren (stali oraz stopów Ni) niskotopliwych metalami (cu, Zn, Col Sn), w warunkach działania naprężeń rozciągających. W artykule przeanalizowano przypadki LME wynikające z penetrowania Cu złączy spawanych rurociągów ze stali 15G29 oraz wysokotemperaturowej erozji płyt ze stali 310 wg ALSI wywołanej działaniem Ni3S2 (Ts-644 °C) oraz erozji kotła ze stali 10CrMo9-10 wywołanym oddziaływaniem w wysokiej temperaturze V2O5 + Na2SO4.

3

Hydrogen and corrosion resistance of Ni-Co superalloys for gas turbine engines blades

63%

Balitskii A. I. , Kvasnitska Y. K. , Ivaskevich L. M. , Mialnitsa H. P.

Archives of Materials Science and Engineering

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2018

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tom Vol. 91, nr 1

5--14

EN

Purpose: This paper is devoted to the investigation of gaseous hydrogen and ash gas turbine fuel influence on the mass loss in long-term corrosion and mechanical properties of cast heat-resistant blade materials. It has been established that the level of corrosion resistance of the investigated alloys (Ni59Cr21Co10W4Ti3Al3MoLa (SM-104-VI); Ni57Cr16Co12W6Ti4Al3Mo2Hf (SM-90-VI); Ni57Cr16Co11W6Ti4Al4Mo2Hf (SM-88U-VI)) correlated with the chromium content and is the highest among similar materials. The advantage of SM-104-VI alloy increases with the increasing of time base and temperature. Design/methodology/approach: This work presents research results concerning corrosion and hydrogen resistance of a investigated alloys examined at a standart mechanical tests under short-term static tension was determined on smooth cylindrical five-time samples with a diameter of the working part 5 mm at speed 1 mm/min. The destructed areas were examined by optical and electron microscopes with computer image analysis. Findings: It has been found that the level of resistance of the investigated alloys high- temperature sulfide and oxide corrosion in the ash of the gas turbine fuel is correlated with the criterion alloying and is the highest among the known materials of the blades. The value of specific mass loss decreases in the order of SM-88U-VI, SM-90-VI, SM-104-VI. Moreover, its advantage over alloys of SM-90-VI and SM-88U-VI as bigger as the time the corrosive environment. Research limitations/implications: An essential problem is the verification of the results obtained using the standart mechanical tests, computer-based image analysis and other methods. Practical implications: The observed phenomena can be regarded as the basic explanation of reduces the plasticity characteristics of the alloys for gas turbine blades. Originality/value: The value of this work is that increasing temperature reduces the negative influence of hydrogen, however, even at 900°C, the values of elongation and transverse contraction in hydrogen is lower than in the air. For a short stretch in the temperature interval 20-900°C the least sensitive to the action of hydrogen at a pressure of 30 MPa is a single crystal SM-90-VI alloy.

4

New Admitance to the Quality Evaluation of Steel Components Refinement

51%

Kučerová J. , Letko I.

Machine Dynamics Problems

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2006

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tom Vol. 30, No. 4

20-28

EN

In terms of ISO 9001, art. 49 we can qualify the heat treatment as one of so called "special processes". With these, we need to find out the identity or non-identity of the products by means of qualified exams (control of fracture surfaces on SEM). This can remarkably increase safety and durability of parts after their converting, because it guarantees the optimal ratio of strenght, plastic and brittle fracture properties. Advantages of the applied method: - Existing verified method and sufficiently augmented instrument technique (SEM). - Operatively and objectivity of the test. - Unpretentiousness of sample preparation. Relatively low price, regarding the heat treatment batch price, or complaints expenses.

5

Stale ferrytyczne odporne na korozję

51%

Wróbel M. , Nowak S. , Blicharski M.

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tom R. XXIV, nr 3

101--110

PL

Dla wybranych stali trzech generacji (stale niestabilizowane o zawartości węgla 0,12/0,2 %, stale stabilizowane i superferrytyczne) wprowadzanych na rynek wraz z rozwojem metod rafinacji, podano składy chemiczne, podstawowe własności mechaniczne i temperatury eksploatacji. Omówiono temperaturę przejścia w stan kruchy, kruchość 475 stopni Celsjusza, kruchość powodowaną wydzielaniem się faz międzymetalicznych, odporność na korozję i spawalność tych stali.

EN

The chemical composition, mechanical properties and typical exploitation temperatures of some selected ferritic stainless steels were presented. The steels represent three generation of ferritic stainless steels introduced into marked as a result of development in refining methods used in the metallurgical practice. The ductile-to-brittle transition temperature, 475 degrees centigrade embrittlement, embrittlement resulting from the intermetallic phases precipitation, corrosion resistance and weldability were briefly presented.

6

Irreversible temper embrittlement in the chromium content model alloys.

51%

Pacyna J. , Kokosza A. , Basista Ł.

Inżynieria Materiałowa

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2001

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tom R. XXII, nr 5

695-697

PL

W pracy dokonano oceny zjawiska nieodwracalnej kruchości odpuszczania w dwóch stopach modelowych z chromem. W obu badanych stopach stwierdzono obniżenie udarności przy temperaturach odpuszczania 300-350 stopni Celsjusza przy jednoczesnym zaniku przełomów o charakterze dołeczkowym co najprawdopodobniej było wynikiem rozpuszczenia się węglika epsilon lub skupisk atomów węgla redystrybucją tego pierwiastka do granic tworzącej się substruktury komórkowej.

EN

The paper evaluates the occurence of irreversible temper embrittlement in two chromium content model alloys. In both investigated alloys a lowered impact toughness at tempering tempratures of 300-350 degrees centigrade was found with the simultaneous disappearance of dimpled fracture. It most probably resulted from dissolution of epsilon carbide or carbon clusters and redistribution of this element to the borders of the arising cellular structure.

7

Application of quantitative fractography for the evaluation of hydrogen embrittlement of duplex steel.

51%

Sozańska M.

Inżynieria Materiałowa

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2001

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tom R. XXII, nr 5

865-868

EN

Quantitative fractography methods were applied for the evaluation of hydrogen embrittlement phenomenon in Z2CND2205 duplex steel. An effect of steel mechanical properties recovery after hydrogen charging and holding at a temperature of 200 degrees centigrade was analysed. The subject of the quantitative evaluation was the changes of morphology on fracture surfaces after strength tests.

PL

Metody fraktografii ilościowej zostały zastosowane do oceny zjawiska kruchości wodorowej w stali duplex Z2CND2205. Analizowano efekt odzyskiwania właściwości mechanicznych stali po nawodorowaniu i wygrzewaniu w piecu w temperaturze 200 stopni Celsjusza. Przedmiotem ilościowej oceny były zmiany morfologii przełomów po badaniach wytrzymałościowych.