Wyniki wyszukiwania - BazTech

1

Microstructure and Mechanical Properties of Welded Joints of Thor 115 Steel

Golański G., Merda A., Klimaszewska E., Urzynicok M., Słania J.

Archives of Metallurgy and Materials

|

2020

|

Vol. 65, iss. 2

743--748

EN

Research was conducted on welded joints of martensitic steel Thor 115 made with two filler materials – CrMo91 and Ni 6082. The scope of the investigations included: non-destructive and destructive testing. The macro- and microstructural investigations revealed correct structure of the weld, without welding imperfections. In the joint welded with Ni 6082, the so-called Nernst’s layers and δ-ferrite grains were visible. The investigations of the analysed joints showed that their properties, i.e. tensile strength and impact strength, were higher than the required minimum, whereas hardness was lower than the maximum value of 350 HV permitted for this group.

2

Examinations of the Welded Joint T91 Steel After Service at Elevated Temperature

Golański G., Merda A., Klimaszewska K., Wieczorek P.

Archives of Metallurgy and Materials

|

2020

|

Vol. 65, iss. 1

237--242

EN

The article provides results of the microstructure examinations and mechanical properties (hardness and microhardness tests) of the welded joint T91 steel taken from the live steam pipeline. Examined joint has been exploited for about 45 000 hours in a temperature of 535°C and the steam pressure equals to 13.5 MPa. Examined joint was made as a double bead by the additional materials with a different chemical composition. It was proved that the joint was characterized by a differential microstructure on the cross-section of the weld. Moreover, decarburized zone in the lower alloyed material and carbides zone in the higher alloyed material were revealed in the weld line and on the boundary penetration of beads. Furthermore, it was shown that the main mechanism of a joint degradation is a privileged precipitation of carbides on the grain boundaries, and an increase of their size.

3

Metallurgical analysis of the causes of failure of the hardening furnace conveyor belt

Merda A., Klimaszewska K., Sroka M., Golański G.

Archives of Materials Science and Engineering

|

2019

|

Vol. 98, nr 2

68--73

EN

Purpose: The aim of the tests was to analyze the microstructure and mechanical properties of a section of the hardening furnace conveyor belt serviced at the temperature of 880-920°C in the carburizing atmosphere, in the context of determining the probable causes of its failure. Design/methodology/approach: The scope of performed tests included: chemical composition analysis of the steel and particles, microstructure investigated using optical and scanning electron microscopy, X-ray phase analysis. Findings: The analysis of the chemical composition showed that the examined material was austenitic steel X15CrNiSi25-21 (S310). Performed metallurgical tests showed that after the service the examined steel was characterized by austenitic structure with numerous precipitates of diverse morphology. In the structure the sigma phase particles and probably the M23C6 carbides precipitates were observed. The continuous grid of precipitates on the boundaries of grains (mainly the sigma phase) and the influence of the cyclic changing heat loads (or thermo-mechanical loads) were the main causes of failure of the analysed detail. Research limitations/implications: The aim of the work was to determine the probable causes of damage of the material used for a conveyor belt of a hardening furnace. Practical implications: The results of investigation and analysis of the metallographic of het-resisting austenitic steel X15CrNiSi25-21 (S310) after service at the temperature of 880-920°C are presented. Originality/value: The paper presents the results of research on the microstructure and mechanical properties of the section of hardening furnace conveyor belt made of creepresisting austenitic steel. The aim of the performed tests was to determine the probable causes of damage of the analysed detail.

4

Struktura i właściwości mechaniczne złącza ze stali T91 z niskostopową warstwą graniową

Wojsyk K., Merda A., Cieślak E., Golański G.

Przegląd Spawalnictwa

|

2018

|

R. 90, nr 6

29--33

PL

W pracy przedstawiono wyniki badań metalograficznych złącza stali T91 spawanego dwoma materiałami dodatkowymi. Ścieg przetopowy wykonany był materiałem dodatkowym o składzie chemicznym zbliżonym do stali 10H2M, ścieg wypełniający materiał o składzie stali T/P91. Badane złącze poddane było obróbce cieplnej – wyżarzaniu 760 °C/2h. Badania nieniszczące i niszczące wykazały, że analizowane złącze spawane spełniało wymagania jakościowe na poziomie B oraz charakteryzowało się wymaganymi lub dostatecznymi właściwościami mechanicznymi. Badania strukturalne wykazały występowanie pomiędzy ściegiem graniowym a wypełniającym pojedynczej, o szerokości i długości rzędu kilku ziaren, strefy odwęglonej.

EN

The paper presents the results of metal science research of the T91 steel joint welded with two additional materials. The root pass was made with the additional material with its chemical composition similar to that of the 10H2M steel, and the fill pass was made with the material of the chemical composition of T/P91 steel. The examined joint was subject to heat treatment annealing 760 °C/2h. The non-destructive and the destructive tests proved that the investigated welded joint fulfilled the quality requirements at the B level and was characterised by the required or satisfactory mechanical properties. The structural tests showed the occurrence of a single decarburised zone, its width and length being of the order of several grains, between the root pass and the fill pass.

5

Microstructure and mechanical properties of a similar T24 steel welded joint after service

Merda A., Golański G., Urbańczyk P., Klimaszewska K.

Prace Instytutu Metalurgii Żelaza

|

2018

|

T. 70, nr 2

37--41

EN

The material under investigation was a welded joint made of 7CrMoVTiB10-10 (T24) steel after 36,000 hours of use at the temperature of 540°C and pressure of 27 MPa. The test samples for the study were taken from a membrane wall of a USC steam boiler. The research scope included: analysis of chemical composition of the original and the additional material (weld pass), investigation of the microstructure using optical microscopy and scanning electron microscopy, as well as tests of mechanical properties of the joint - hardness measurement. It was proved that the investigated joint was characterised by a regular structure, without any welding defects, which probably resulted from the application of the additional material based on the CrMo steel from the weld root side. The observation showed that the microstructure of the original material consisted of granular bainite with numerous precipitates. In the heat affected zone and in the weld, the microstructure of lath bainite (bainitic-martensitic microstructure) was observed, also with numerous precipitates. The hardness of the analysed joint was lower than the limiting value of 350HV.

PL

Badaniu poddano jednoimienne złącze spawane stali 7CrMoVTiB10-10 (T24) po ok. 36 000 godzinach eksploatacji w temperaturze 540°C i ciśnieniu 27 MPa. Próbki do badań pobrano z wycinka ściany szczelnej kotła energetycznego na parametry nadkrytyczne. Zakres przeprowadzonych badań obejmował: analizę składu chemicznego materiału rodzimego oraz materiału dodatkowego, badania mikrostrukturalne za pomocą mikroskopii świetlnej i skaningowej mikroskopii elektronowej oraz badania właściwości mechanicznych złącza - pomiar twardości. Wykazano, że badane złącze charakteryzuje się prawidłową budową, bez niezgodności spawalniczych, co zapewne wynika z zastosowania od strony grani materiału dodatkowego na bazie stali CrMo. Przeprowadzone obserwacje wykazały, że mikrostruktura materiału rodzimego składa się z bainitu ziarnistego z licznymi wydzieleniami. W strefie wpływu ciepła i spoinie obserwowano mikrostrukturę bainitu listwowego (bainityczno-martenzytyczną) również z licznymi wydzieleniami. Twardość analizowanego złącza była niższa od wartości granicznej wynoszącej 350HV.

6

Microstructure and mechanical properties of the Sanicro 25 steel after ageing

Merda A., Sroka M., Klimaszewska K., Golański G.

Journal of Achievements in Materials and Manufacturing Engineering

|

2018

|

Vol. 91, nr 1

5--11

EN

Purpose: The purpose of the research was to determine and analyse the changes in the microstructure and mechanical properties of the Sanicro 25 steel in the as-received condition and after ageing at 600, 650 and 700°C for up to 10,000 hours. Design/methodology/approach: The scope of the investigations included: microstructural investigation – SEM microscopy, analysis of precipitation performed using TEM microscopy, investigation of mechanical properties, Vickers hardness measurement. Findings: In the as-received condition, the Sanicro 25 steel was characterised by austenitic microstructure with annealing twins and numerous primary precipitates. The analysis of Sanicro 25 steel microstructure after ageing at 600 and 700°C for up to 10,000 hours revealed significant changes in the microstructure consisting mainly in a tendency to create unfavourable morphology of secondary precipitates – M23C6 carbides that form continuous carbide systems along the grain boundaries. The observations have shown that during long-term ageing the secondary carbides were also precipitated inside the grains and at the interface of three grain boundaries – σ phase. Research limitations/implications: The analysis of the microstructure of the examined steel using SEM and TEM was performed to determine the influence of ageing on the processes of changes in the precipitate morphology. Practical implications: The results obtained based on the performed research constitute a building block for the degradation characteristics of the microstructure and mechanical properties of the 23/25-type austenitic steels. Originality/value: The results of the investigation and analysis of the metallographic and mechanical properties of the Sanicro25 austenitic steel in as-received condition and after ageing are presented.

7

Nowe żarowytrzymałe stale o strukturze austenitycznej dla energetyki

Golański G., Merda A., Klimaszewska K.

Hutnik, Wiadomości Hutnicze

|

2018

|

Vol. 85, nr 12

410--416

PL

Rozwój przemysłu energetycznego determinowany jest obecnie wymaganiami środowiskowymi Unii Europejskiej, co wymusza stosowanie rozwiązań proekologicznych, których celem jest ograniczenie negatywnego wpływu tej dziedziny gospodarki na środowisko. Jednym z takich rozwiązań jest wzrost parametrów pracy bloków energetycznych, celem ograniczenia emisji zanieczyszczeń oraz podwyższenie ich sprawności. Wzrost parametrów pracy bloków wymusza wprowadzenie nowych, żarowytrzymałych materiałów konstrukcyjnych między innymi nowoczesnych, żarowytrzymałych stali austenitycznych. W artykule na podstawie badań własnych oraz danych literaturowych przedstawiono podstawową charakterystykę nowoczesnych żarowytrzymałych stali austenitycznych w stanie dostawy – TP374HFG, Super 304H, HR3C oraz Sanicro 25.

EN

The development of the power industry is currently determined by the environmental requirements of European Union, which forces the use of proecological solutions. The aim of these solutions is limiting the negative influence of this branch of economics on the environment. One of these solutions consists in raising the working parameters of power units to limit the emission of pollution and increase the efficiency. The growth of the parameters of work of power units forces the introduction of modern creep-resisting construction materials, among other, the modern creep-resisting austenitic steels. The paper presents the basic characteristics of modern creep-resisting austenitic steels in delivery condition: TP374HFG, Super 304H, HR3C and Sanicro 25 on the basis of the authors’ research and the literature data.

8

Analiza mikrostruktury i właściwości mechanicznych stali VM12-SHC po eksploatacji

Klimaszewska K., Merda A., Urbańczyk P., Golański G.

Hutnik, Wiadomości Hutnicze

|

2018

|

Vol. 85, nr 12

424--426

PL

Badaniom poddano stal VM12-SHC po eksploatacji w temperaturze 545-560°C przy ciśnieniu pary 4,5 MPa po czasie 18 301 godzin. Zakres przeprowadzonych badań obejmował: określenie składu chemicznego zrealizowane za pomocą spektrometru iskrowego SpectroLab K2 oraz analizę mikrostrukturalną wykonaną za pomocą skaningowego mikroskopu elektronowego (SEM). Zakres przeprowadzonych badań mechanicznych obejmował: pomiar twardości metodą Vickers’a, statyczną próbę rozciągania oraz próbę udarności. Analizę wydzieleń przeprowadzono za pomocą metody izolatów węglikowych. Badana stal po eksploatacji charakteryzowała się strukturą martenzytyczną z licznymi wydzieleniami węglików M23C6, fazy Lavesa oraz złożonych azotków CrNbN (faza Z). Przeprowadzone badania mikrostruktury i właściwości mechanicznych stali VM12-SHC wykazały względnie niewielki stopień degradacji badanego materiału, co przełożyło się na zachowane nadal wysokie właściwości mechaniczne badanej stali.

EN

The investigated material was VM12-SHC steel after service at the temperature of 545-560°C and steam pressure of 4.5 MPa after 18 301 hours. The scope of the research included: the study of the chemical composition using a spark spectrometer SpectroLab K2, and microstructural tests by a scanning electron microscope (SEM). The scope of mechanical tests included: the hardness measurement by the Vickers method, the static test of tension and the impact strength test. The analysis of precipitates was performed using the method of carbide isolates. The examined steel after service was characterised by a martensitic structure with numerous precipitations of M23C6 carbides, Laves phase and CrNbN (Z phase). The tests performed on the microstructure and mechanical properties of VM12-SHC steel showed a relatively minor degree of degradation of the examined material, which was reflected in high mechanical properties of the investigated steel.

9

Zmiany w mikrostrukturze stopu na bazie niklu HR6W po starzeniu

Merda A., Golański G., Zieliński A.

Energetyka

|

2018

|

nr 11

630--632

PL

Badaniu metalograficznemu w stanie dostawy oraz po procesie starzenia w temperaturze 700°C i czasach do 10 000 godzin poddano stop na bazie niklu HR6W. Zakres przeprowadzonych badań obejmował: badania strukturalne za pomocą mikroskopii optycznej i skaningowej mikroskopii elektronowej, identyfikację wydzieleń z wykorzystaniem dyfrakcji elektronowej oraz pomiar twardości. Przeprowadzone badania wykazały, że w stanie dostawy w analizowanym stopie występowały jedynie wydzielenia typu MX, natomiast długotrwałe starzenie przyczyniło się do wydzielenia się licznych cząstek faz wtórnych: węglików M23C 6, fazy Lavesa oraz złożonych kompleksów. Intensywny przebieg procesów wydzieleniowych skutkował wzrostem twardości badanego stopu.

EN

The nickel-based HR6W alloy was subject to metallographic tests in the as-received state and after the ageing process at the temperature of 700°C and times up to 10 000 hours. The scope of the performed tests included the structural tests using optical microscopy and scanning electron microscopy, the identification of precipitates using electron diffraction TEM and the measurement of hardness. The tests showed that in the as-received state in the analysed alloy, only the MX type of precipitates occurred, and that the long-term ageing contributed to the precipitation of numerous particles of secondary phases: M23C6 carbides, Laves phase, and compound complexes. The intense course of precipitation processes resulted in the growth of hardness of the examined alloy.

10

Nowe żarowytrzymałe stopy o strukturze austenitycznej dla energetyki zawodowej

Merda A., Golański G., Zieliński A.

Energetyka

|

2018

|

nr 3

142--146

PL

Polityka dekarbonizacji energetyki prowadzona przez Unię Europejską i wynikające z niej coraz bardziej restrykcyjne przepisy w zakresie ochrony środowiska, wymagają zwiększenia sprawności cieplnej bloków energetycznych. Wyższa temperatura i ciśnienie pary w blokach pracujących przy tzw. nadkrytycznych, czy też ultranadkrytycznych parametrach wymuszają stosowanie materiałów spełniających wysokie wymagania właściwości użytkowych na elementy konstrukcyjne kotłów pracujące w określonych warunkach temperaturowo-naprężeniowych i agresywnego środowiska. Do nowoczesnych materiałów o wysokiej żarowytrzymałości i żaroodporności należy zaliczyć stopy o strukturze austenitycznej – stal austenityczna X7NiCrWCuCoNbNB25-23-3-3-2 (Sanicro 25) oraz stop niklu 23Cr-45Ni-6W-Nb-Ti-B (HR6W). W artykule przedstawiono charakterystykę tych stopów, która obejmowała analizę: składu chemicznego, obróbki cieplnej, mikrostruktury, mechanizmów umocnienia oraz właściwości mechanicznych.

EN

Decarbonization policy of the power industry pursued by the EU and the related more and more restrictive regulations of environment protection require increasing of power units thermal efficiency. Higher temperature and steam pressure in power units working with the supercritical or ultra supercritical parameters oblige to use materials that fulfil high requirements as to functional properties of boilers construction elements that work under certain conditions of temperature, stress and aggressive environment. Modern materials of high creep and heat resistance include alloys of austenitic structure – austenitic steel X7NiCrWCuCoNbNB25-23-3-3-2 (Sanicro 25) and nickel alloy 23Cr-45Ni-6W-Nb-Ti-B (HR6W). Presented is here the characteristics of these alloys, including the analysis of chemical composition, heat treatment, microstructure, strengthening mechanisms and mechanical properties.

11

Analysis of the microstructure and properties of T92 steel after long-term service

Merda A., Klimaszewska K., Sroka M., Wieczorek P, Golański G.

Archives of Materials Science and Engineering

|

2018

|

Vol. 93, nr 1

5--11

EN

Purpose: The purpose of the investigation was to determine and analyse the changes in the microstructure and mechanical properties of the T92 steel after service in creep conditions of the following parameters: temperature – 575°C, pressure – 28.2 MPa, service time – 41914 hrs. Design/methodology/approach: The tests were performed on the test samples taken from a pipe section of a steam superheater after long-term service. The range of the investigations included: microstructural investigation – the optical and SEM microscopy, the analysis of precipitation – carbide isolates, the investigation of mechanical properties: the Vickers hardness measurement, the impact test and static tensile test. Findings: The performed tests showed a slight degree of exhaustion of the structure of the analysed T92 steel. The relatively small changes in the microstructure of the examined steel were reflected in the still retained high mechanical properties. Research limitations/implications: he analysis of the microstructure of the examined steel using SEM was performed to determine the influence of the service on the processes of changes in the precipitate morphology. Practical implications: The metal science investigation of the sections taken from the elements of the power installations after long-term service is one of the basic elements of building the data base of materials and their joints used in the power industry. The results obtained from the performed research constitute a building block for the degradation characteristics of the microstructure and mechanical properties of martensitic steels of the 9-12%Cr type. Originality/value: The results of investigation and analysis of the metallographic and mechanical properties of martensitic T92 steel after long-term service are presented.

12

Microstructure and mechanical properties of HR3C austenitic steel after service

Golański G., Kolan C., Zieliński A., Klimaszewska K., Merda A., Sroka M., Kłosowicz J.

Archives of Materials Science and Engineering

|

2016

|

Vol. 81, nr 2

62--67

EN

Purpose: The purpose of the investigations was to determine changes in the microstructure and mechanical properties of HR3C creep resisting austenitic steel after service. Design/methodology/approach: The investigations were performed on test specimens taken from a part of the steam superheater tube. The range of the investigations included: microstructural investigations - light and SEM microscope; analysis of precipitates - carbide isolates; investigations of mechanical properties - hardness measurement, static tensile test, impact test. Findings: The precipitation processes at the grain boundaries lead to increase in intergranular corrosion of the HR3C steel resulting in loss of grains in the structure. The impact strength testing on test specimens with reduced width may result in overestimation of crack resistance of the material after service. Research limitations/implications: The comprehensive analysis of precipitation processes requires TEM examinations. Finding the correlation between the impact strength determined on standard vs. non-standard test specimens with reduced width. Practical implications: The obtained results of investigations are used in industrial practice for diagnosis of pressure parts of power boilers. Test procedures developed based on comprehensive materials testing conducted under laboratory conditions are used in upgrading and design of pressure parts of steam boilers. The results of investigations are also the element of database of the materials characteristics of steels and alloys as well as welded joints made of them working under creep conditions developed by the Institute for Ferrous Metallurgy. Originality/value: The results and analysis of the investigations of microstructure and mechanical properties of HR3C steel after service under actual boiler conditions are presented.