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1

Crystallization of GX2CrNiMoCuN 25-6-3-3 Grade Alloy Cast Steel and its Microstructure in the As-cast State and After Heat Treatment

Wróbel Tomasz, Jurczyk Paweł, Baron Czesław, Nuckowski Paweł M.

Archives of Foundry Engineering

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2023

|

Vol. 23, iss. 3

94--103

EN

The paper presents the results of research conducted in the field of crystallization and microstructure of duplex alloy cast steel GX2CrNiMoCuN 25-6-3-3 grade. The material for research was the above-mentioned cast steel with a chemical composition compliant with the relevant PN-EN 10283 standard, but melted at the lowest standard allowable concentration of alloying additives (some in short supply and expensive), i.e. Cr, Ni, Mn, Mo, Cu and N. The analysis of the crystallization process was performed based on the DTA (Derivative Thermal Analysis) method for a stepped casting with a thickness of individual steps of 10, 20, 40 and 60 mm. The influence of wall thickness was also taken into account in the cast steel microstructure testing, both in the as-cast state and after solution heat treatment. The phase composition of the cast steel microstructure was determined by using an optical microscope and X-ray phase analysis. The analysis of test results shows that the crystallization of tested cast steel uses the ferritic mechanism, while austenite is formed as a result of solid state transformation. The cast steel under analysis in the as-cast state tends to precipitate the undesirable σ-type Fe-Cr intermetallic phase in the microstructure, regardless of its wall thickness. However, the casting wall thickness in the as-cast state affects the austenite grain size, i.e. the thicker the casting wall, the wider the γ phase grains. The above-mentioned defects of the tested duplex alloy cast steel microstructure can be effectively eliminated by subjecting it to heat treatment of type hyperquenching.

2

The effects of arc voltage and shielding gas type on the microstructure of wire arc additively manufactured 2209 duplex stainless steel

Kemény Dávid Miklós, Sándor Bence, Varbai Balázs, Katula Levente Tamás

Advances in Materials Science

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2023

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Vol. 23, nr 4(78)

62--82

EN

Duplex stainless steels (DSSs) are widely used due to their corrosion resistance. Austenite and ferrite determine the excellent properties. Ferrite provides strength and good corrosion resistance, while austenite provides toughness and weldability. During our research,samples were producedwith ER 2209 duplex steel wire using wirearc additive manufacturing (WAAM). Two different 17V and 19V arc voltages were used during the production. Two shielding gases were used for each voltage: M12-ArC-2.5 and M12-ArHeC-20/2. The research aimed to determine the ferrite ratio as a function of the welding parameters. The ferrite(or austenite)content must be between 30% and 70% for duplex stainless steel welds, according to the ISO 17781 standard.Based on our research, it can be stated that the austenite ratio increases as the voltage increases, thus failing to fulfill the standard's requirements. The helium content reduced the ferrite ratio even when the 17V voltage was used due to the gas's higher ionizationpotential. During the metallographicexamination, our welded samples met the standardrequirements for the austenite content for17V arc voltage and M12-ArC-2.5 shielding gas. The ferrite content in the entire sample cross-sectionfell between 30-42% duringferitscopeand image analysis measurements. These welding parameters can be recommended for industrial applications.

3

Influence of flame straightening on the properties of welded joints made of X2CrNi22-2 duplex steel

Lange Artur

Materials Science Poland

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2021

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Vol. 39, No. 3

446--457

EN

The study investigates the optimal conditions associated with flame straightening of welded joints in duplex steel grade X2CrNi22-2. The research aimed to assess the influence of heat, applied during flame straightening of welded structures in X2CrNi22-2 grade steel, on the properties of the welded joints. Based on the macroscopic, microscopic, and strength tests conducted on welding joints in X2CrNiN22-2-grade duplex steel that have been subjected to flame straightening, it was ascertained that post-welding flame straightening of this grade of steel, at a treatment temperature of 730°C, should not take place for >1 min. The temperature of 730°C has been chosen as a reference because of the assumption that the welded joints are heated to the temperature of 700–730°C during straightening with an acetylene-oxygen flame. The paper scrutinizes the questions of (i) what changes occur in the welded joints as a result of flame straightening carried out in this temperature range and (ii) what impact those changes have on the joint strength. The results of our study indicate that the duration of post-welding flame straightening of X2CrNiN22-2-grade duplex steel, at a treatment temperature of 730°C, should not exceed 1 min.

4

The effect of cavitation erosion on austenitic-ferritic steel

Krawczyk J., Jasionowski R., Ura D., Goły M., Frocisz Ł.

Zeszyty Naukowe Akademii Morskiej w Szczecinie

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2018

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nr 56 (128)

30--35

EN

Cavitation is a one of many wear mechanisms which are related to the flow of liquid. It is one of the most destructive wear methods for stainless materials. The local changes in the pressure of the liquid stream related to the flow across the metal component cause straightening of the surface area, as well as its erosion and the formation of pits on the surface layer. The erosion value of cavitation is related to the material’s microstructure, the geometry of the element, the phase composition of the material and the surface roughness. In this paper the investigation of the cavitation process for duplex stainless steel has been performed. Samples examined in the first stages of the experiments were not significantly changed, but after a long time the hardness increase was very visible. The result of the cavitation was also cracking along the interphase boundaries, which resulted in the chipping of the material. One of the most important results was a description of the change in the wear mechanisms and its intensity during the cavitation exposure time. At first plastic micro deformation of the material’s surface occurred, then the plastic deformation increased significantly and after some time this resulted in erosion of the material and interfacial boundary decohesion; these two effects increased simultaneously. The last of the mechanisms was mechanical destabilization of the austenite, but the clear result of the mechanical destabilization of the austenite was only observed in the last sample. Martensitic transformation of the material changed the material’s mechanical properties, but for the stainless steels this resulted in electrochemical corrosion of the material, especially through the formation of an electrochemical potential between austenite and martensite.

5

Spawanie łukowe stali duplex pod kątem maksymalizacji odporności połączeń spawanych na korozję wżerową w środowisku chlorków

Stankiewicz M., Ślązak B.

Przegląd Spawalnictwa

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2018

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R. 90, nr 5

142--150

PL

Dwufazowe stale ferrytyczno-austenityczne typu duplex wykazują doskonałą kombinację właściwości mechanicznych i odporności na korozję, w tym szczególnie agresywną korozję wżerową w środowisku chlorkowym. Pomimo wiedzy i doświadczenia zdobytego podczas spawania tych stopów aktualnie nadal obserwuje się problemy ujawniane w trakcie badań korozyjnych. Dobrze uzasadniony termin „dobra spawalność” odnosi się wyłącznie do grupy cech technologicznych ułatwiających łączenie elementów metalowych przez spawanie, ale nie oznacza automatycznie wysokiej odporności na korozję połączeń spawanych, która w środowisku chlorków osiąga tylko 50÷80% materiału rodzimego. W artykule zostały omówione wszystkie czynniki metalurgiczne oraz technologiczne mające wpływ na końcowe właściwości korozyjne złączy spawanych.

EN

Two-phase ferrite-austenitic duplex stainless steels demonstrate excellent combination of strength and corrosion resistance including particularly aggressive pitting corrosion in chloride environment. The use of duplex and super-duplex stainless steels has continued to increase since last decade of XX century but despite of the knowledge and experience acquired there are still problems encountered in practice. Well justified term "good weldability" refers exclusively to the group of technological features for easy metal parts joining by welding, but not to the automatic provision of corrosion resistance of welding joints, which in chlorides environment reaches only 50÷80% of original parent material resistance. Welding technology factors and impact on final corrosion resistance of welds are widely discussed. This includes particularly weld chemical composition, heat input balance, oxidation, nitrogen content, shielding and purging gas, and the practical constraints of the welding process.

6

Zbrojenie ze stali nierdzewnej jako sposób na wydłużenie trwałości konstrukcji żelbetowych

Jaśniok M.

Przegląd Budowlany

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2018

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R. 89, nr 11

24--27

PL

Artykuł opisuje sposób wydłużenia trwałości konstrukcji żelbetowej przez zastosowanie stali nierdzewnej zamiast tradycyjnej stali węglowej. Na wstępie wyjaśniono termin „stal nierdzewna” oraz opisano trzy rodzaje struktury stali stosowanej jako zbrojenie do betonu: austenityczną, ferrytyczną i duplex. Omówiono właściwości mechaniczne i fizyczne tych stali, a następnie porównawczo opisano przebieg i skutki ich degradacji korozyjnej wywołanej przez różne poziomy stężeń chlorków w betonie. W podsumowaniu przedstawiono przykład ciekawego zastosowania zbrojenia ze stali austenitycznej w odpowiedzialnej konstrukcji betonowej.

EN

This article describes the way of extending the durability of reinforced concrete structure by using stainless steel instead of traditional carbon steel. The term „stainless steel” was first explained and three types of steel structure used as reinforcement for concrete were described: austenitic, ferritic and duplex. Mechanical and physical properties of these steels were discussed, and then the course and effects of their corrosion degradation caused by different levels of chloride concentrations in concrete were compared. The summary presents an interesting example of the use of austenitic steel reinforcement in a responsible concrete structure.

7

The sigma phase precipitation during high temperature deformation of the X2CrNiMoN25-7-4 duplex steel

Stradomski G., Jasińska J., Laber K., Sawicki S.

Hutnik, Wiadomości Hutnicze

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2018

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Vol. 85, nr 2

54--57

EN

Steels and other ferrous alloys are very well known as construction materials and still are widely used and in the near future this will not change. Duplex steels due to the two-phase construction combine high corrosion resistance and good mechanical properties. Both those parameters are at higher level than austenitic stainless steels and that why duplex steels are irreplaceable material in many fields like the petrochemical, power, pulp and paper, and food industry. This multiphase microstructure generates a lot of problems which have already been repeatedly presented in many works. Among the steels and cast steels resistant to corrosion most modern and dynamically developing group are ferritic-austenitic alloys, commonly known as duplex. The chemical composition of a steel containing about 0.02% C, 26% Cr, 6.5% Ni, 3% Mo, 1.4% Mn, 0.2% N guarantees that already after casting is obtained ferritic - austenitic structure. The paper present results of the X2CrNiMoN25-7-4 duplex steel physical tests made with the Gleeble 3800 machine. The research concerns problems of the influence of primary structure on the plasticity and sigma phase formation.

PL

Stale obok innych stopów żelaza są dobrze znanymi, szeroko wykorzystywanymi materiałami konstrukcyjnymi i sytuacja taka w najbliższej przyszłości nie ulegnie zmianie. Stale dupleks dzięki swojej dwufazowej budowie cechuje wysoka odporność korozyjna oraz wysokie właściwości mechaniczne. Obydwa te parametry są na wyższym poziomie niż stali austenitycznych i dlatego stale dupleks są niezastąpionym materiałem w wielu gałęziach przemysłu jak petrochemiczny, energetyczny, papierniczy czy w produkcji żywności. Taka budowa mikrostruktury powoduje pojawienie się wielu problemów, które już w wielu pracach były szeroko omawiane. Wśród stali i staliwa odpornego na korozję najszybciej rozwijającą się grupą są stopy ferrytyczno-austenityczne znane również jako dupleks. Skład chemiczny stali zawierającej 0,02% C, 26% Cr, 6,5% Ni, 3% Mo, 1,4% Mn, 0,2% N gwarantuje uzyskanie już w stanie lanym mikrostruktury ferrytyczno-austenitycznej. W pracy przedstawiono wyniki badań fizycznych przeprowadzonych z wykorzystaniem urządzenia Gleeble 3800 na stali X2CrNiMoN25-7-4. Badania dotyczą problemów wpływu mikrostruktury pierwotnej na plastyczność oraz wydzielanie się fazy sigma.

8

Effect of Shielding-Gas Nitrogen Content on the Properties of TIG and A-TIG Orbital-Welded Tubular Joints Made of Duplex Steel

Kiszka A., Czupryński A., Baszczyńska E.

Biuletyn Instytutu Spawalnictwa w Gliwicach

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2018

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Vol. 62, No. 2

35--40

EN

The article discusses tests results concerning the joining of duplex steel pipes performed using the TIG and A-TIG (with the addition of activating flux) orbital welding technology. The shielding gas used in related tests contained pure argon as well as argon with an addition of nitrogen. Technological welding tests were performed using a closed head without the feeding of a filler metal. The research work included visual and penetrant tests as well as macro and microscopic observations and ferrite meter-aided measurements of the ferrite content in welds.

PL

Omówiono wyniki badań dotyczących łączenia rur ze stali duplex z wykorzystaniem technologii spawania orbitalnego TIG i A-TIG (z dodatkiem topnika aktywującego). Jako gaz osłonowy stosowano zarówno sam argon, jak również argon z dodatkiem azotu. Przeprowadzono próby technologiczne spawania z użyciem głowicy zamkniętej bez podawania materiału dodatkowego. Wykonano badania wizualne i penetracyjne, następnie badania makro i mikroskopowe, a także pomiary zawartości ferrytu w spoinach z wykorzystaniem ferrytomierza.

9

Effect of Silicon Addition on the Microstructure of Cast 24Cr-5Ni-2.5Mo-xSi Duplex Steel

Kalandyk B., Zapała R., Witkowska M., Kowalska J.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 1

186--190

EN

Characteristics of the microstructure of corrosion-resistant cast 24Cr-5Ni-2.5Mo duplex steel after introduction of 0.98, 1.67 and 4.3% Si were described. Based on the test results it has been found that silicon addition introduced to the corrosion-resistant cast two-phase duplex steel significantly reduces austenite content in the alloy matrix. Increasing silicon content in the test alloy to 4.3% has resulted, in addition to the elimination of austenite, also in the precipitation of Si-containing intermetallic phases at the grain boundaries and inside the grains. The precipitates were characterized by varying content of Cr and Mo, indicating the presence in the structure of more than one type of the brittle phase characteristic for this group of materials. The simulation using Thermo-Calc software has confirmed the presence of ferrite in all tested alloys. In the material containing 4.3% Si, the Cr and Si enriched precipitates, such as G phase and Cr3Si were additionally observed to occur.

10

Analiza czasu i wydajności spawania stali superdupleks

Chudziński M.

Postępy w Inżynierii Mechanicznej

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2017

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nr 10(5)

5--14

PL

Praca zawiera charakterystykę stali dupleks oraz ilościowe statystyki i prognozy jej zastosowania. Przedstawiono także teorię w zakresie obliczania czasu głównego i czasu całkowitego spawania na podstawie objętości wykonywanej spoiny oraz współczynnika czasu jarzenia się łuku i wydajności stapiania. W części badawczej wykonano analizę porównawczą czasu i wydajności spawania w pozycji PF złącza blach o grubości 8 mm ze stali superdupleks X2CrNiMoN25-7-4 (1.4410), spawanego różnymi metodami. Analiza czasów oraz wydajności spawania pozwoliła ustalić różnice w tym zakresie między możliwymi do zastosowania metodami spawania i potwierdzić kilkukrotnie wyższą wydajność metody 136 (FCAW) niż pozostałych badanych: 111 (SMAW) i 141 (GTAW).

EN

This paper contains the characteristics of duplex steel and the quantitative statistics and forecasts for its use. There is presented theory of calculating main welding time and total welding time based on the volume of the weld, time factor of the arc's glow and melt efficiency. The comparative analysis of the welding time and efficiency in the PF position of the 8mm sheet metal joint of X2CrNiMoN25-7-4 (1.4410) superduplex stainless steel welded by various processes was performed. Analysis of welding times and weld efficiency has allowed us to determine the differences between the applicable welding processes and to confirm several times higher efficiency of the 136 process (FCAW) from the other examined: 111 (SMAW) and 141 (GTAW).

11

Stopowe stale austenityczne, ferrytyczne i duplex używane w transporcie

Kułakowski M., Rokosz K.

Autobusy : technika, eksploatacja, systemy transportowe

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2017

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R. 18, nr 7-8

357--362

PL

Stopowe stale austenityczne, ferrytyczne i austenityczno-ferrytyczne duplex znajdują szerokie zastosowanie w przemyśle samochodowym do produkcji różnych elementów podjazdów samochodowych. Są to główne rodzaje stali nierdzewnych, wykorzystywane do wytwarzania całej gamy części samochodowych. W pracy przedstawiono szeroki zakres zastosowań poszczególnych grup stali. Szczególny nacisk położono na ich właściwości oraz cechy materiałów. Omówiono poszczególne grupy z uwzględnieniem struktury metalograficznej Duży nacisk położono na ferrytyczo-austenityczną stal duplex ze względu na jej możliwości i lepsze właściwości w wielu przypadkach od pozostałych analizowanych gatunków stali.

EN

Alloy austenitic, ferritic and austenitic-ferritic duplex steels are widely used in the automotive industry for the manufacture of various car elements. These are the main types of stainless steels used to produce a whole range of automotive parts. That work presents a wide range of applications for each indicated steel groups. Particular emphasis was placed on their properties and characteristics of materials. The groups were discussed taking into account the metallographic structure. The emphasis was on the ferritic-austenitic duplex steel due to its capabilities and improved properties in many cases from the other steel grades analyzed.

12

Effect of post-weld heat treatment on thermal diffusivity in UNS S32304 duplex stainless steel welds

Betini E. G., Mucsi C. S., Luz T. S., Orlando M. T. D., Avettand-Fènoël M.-N., Rossi J. L.

Archives of Materials Science and Engineering

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2017

|

Vol. 88, nr 2

49--58

EN

Purpose: The thermal diffusivity variation of UNS S32304 duplex stainless steel welds was studied after pulsed GTA welding autogenous process without filler addition. This property was measured in the transverse section of thin plates after welding process and post-heat treated at 750°C for 8 h followed by air-cooling. Design/methodology/approach: The present work reports measurements of thermal diffusivity using the laser-flash method. The thermal cycles of welding were acquired during welding by means of k-type thermocouples in regions near the weld joint. The used shielding gas was pure argon and 98% argon plus 2% of nitrogen. The temperature profiles were obtained using a digital data acquisition system. Findings: It was found an increase of thermal diffusivity after welding process and a decrease of these values after the heat treatment regarding the solidified weld pool zone, irrespective of the welding protection atmosphere. The microstructure was characterized and an increase of austenite phase in the solidified and heat-affected zones was observed for post-weld heat-treated samples. Research limitations/implications: It suggests more investigation and new measurements about the influence of the shielding gas variation on thermal diffusivity in the heat-affected zone. Practical implications: The nuclear industry, especially, requests alloys with high thermal stability in pipes for power generation systems and safe transportation equipment’s for radioactive material. Thus, the duplex stainless steel grades have improved this stability over standard grades and potentially increase the upper service temperature reliability of the equipment. Originality/value: After heat treatment, the welded plate with 98%Ar plus 2%N2 as shielding gas presented a thermal diffusivity closer to the as received sample. By means of 2%-nitrogen addition in shielding gas during GTAW welding of duplex stainless steel may facilitate austenite phase reformation, and then promotes stability on the thermal diffusivity of duplex stainless steels alloys.

13

Corrosion of X2CRNiN23-4 lean duplex stainless steel annealed at 485°C

Lipiński T.

Problemy Eksploatacji

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2016

|

no. 3

187--195

EN

Lean duplex stainless steels are ferritic-austenitic steel, and they present the excellent corrosion resistance of austenite steel and the high mechanical behaviour of ferrite steel. General important corrosion problems in duplex stainless steels at 475°C have been already detected. Although the worst temperature is 475°C, corrosion can still form at lower or higher temperatures. The purpose of this work was to ascertain how 30-minutes isothermal heat treatments at 485°C and corrosion time effect the relative mass loss and profile roughness parameters of X2CrNiN23-4 lean duplex stainless steel. The real critical temperature for researching steel was determinate by the DSC method. Corrosion tests were conducted in a nitric acid medium by the measurement of loss in mass (Huey test). The corrosive media was boiling nitric acid V 65%. The corrosion rate of the X2CrNiN23-4 steel was measured in mm/year and in g/m2.

PL

Stale nierdzewne Lean duplex są stalami ferrytyczno-austenitycznymi o doskonałej odporności na korozję stali austenitycznej, a wysokich właściwościach mechanicznych stali ferrytycznej. Ważny problem korozji stali odpornej na korozję duplex w temperaturze 475°C został już stwierdzony. Chociaż najniekorzystniejszą temperaturą jest 475°C, korozja może przebiegać zarówno w temperaturze niższej, jak i wyższej. Celem niniejszej pracy było zbadanie, jak 30-minutowe izotermiczne wyżarzanie stali w temperaturze 485°C oraz czas przetrzymywania w ośrodku korozyjnym wpłynie na ubytek masowy oraz chropowatość powierzchni stali lean duplex w gatunku X2CrNiN23-4. Rzeczywista temperatura krytyczna dla badań stali została określona metodą DSC. Badanie korozyjne (ubytku masy) prowadzono w środowisku kwasu azotowego V 65% w temperaturze wrzenia (test Huey). Prędkość korozji stali X2CrNiN23-4 określono w mm/rok i w g/m2.

14

Corrosion analysis of the X2CrNiMoN25-7-4 super duplex stainless steel

Lipiński T.

Czasopismo Techniczne. Mechanika

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2016

|

Y. 113, iss. 3-M

39--45

EN

Super duplex stainless steels present excellent corrosion resistance of austenite steel and a high mechanical behaviour of ferrite steel. However, performance presented by super duplex stainless steels can be drastically reduced if undesirable phases, such as sigma phase, chi phase, secondary austenite and a lot of rich chromium and carbides precipitate. The purpose of this work was to ascertain how 30-minutes isothermal heat treatments at 530°C and corrosion time effect the relative mass loss and profile roughness parameters of the X2CrNiMoN25-7-4 super duplex stainless steel. The influence of boiling nitric acid on the steel corrosion resistance was investigated using weight loss and roughness parameters.

PL

Stale super duplex posiadają doskonałą odporność na korozję dziedziczną ze stali austenitycznych i wysokie właściwości mechaniczne właściwe dla stali ferrytycznych. Jakkolwiek właściwości stali odpornej na korozję super duplex mogą ulegać gwałtownemu obniżeniu wraz z powstaniem niepożądanych faz, takich jak faza sigma, faza chi, austenit wtórny i wielu innych wydzieleń bogatych w chrom, jak również węglików. Celem tego artykułu było określenie, jak 30 minutowa izotermiczna obróbka cieplna w temperaturze 530°C i czas przetrzymywania materiału w ośrodku korozyjnym wpływa na względny ubytek masy i parametry chropowatości stali odpornej na korozję super duplex X2CrNiMoN25-7-4. Badania wpływu wrzącego kwasu azotowego na odporność korozyjną badano, wykorzystując ubytki masowe i parametry chropowatości.

15

Welding of (Super) Duplex Stainless Steels

Van der Mee V.

Biuletyn Instytutu Spawalnictwa w Gliwicach

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2016

|

Vol. 60, No. 5

44-55

PL

Przedstawiono stale dwufazowe stosowane w nowoczesnych gałęziach przemysłu. Omówiono szczegółowo wszystkie rodzaje tych stali (duplex, super duplex, lean duplex i hyper duplex) i ich własności, ze szczególnym uwzględnieniem odporności na korozję, a także podstawowe obszary zastosowania. Przedstawiono zagadnienia związane z technologią spawania, obejmujące przygotowanie materiału podstawowego, metody i techniki spawania, wymagania odnośnie ilości wprowadzonego ciepła, a także zabiegi cieplne przed i po spawaniu. Zwrócono uwagę na rosnący udział stali dwufazowych, stosowanych na konstrukcje spawane, a także przedstawiono perspektywę dalszego rozwoju.

EN

The article presents and describes in detail duplex steels used in modern sectors of industry (duplex, super duplex, lean duplex and hyper duplex), with particular attention paid to corrosion resistance and primary areas of application. The article also discusses welding-related issues including the preparation of the base material, welding techniques and procedures, requirements concerning heat input as well as pre-weld and post-weld heat treatment. The article emphasizes the growing use of duplex steels, among other things in welded structures, and forecasts their further development.

16

Technology of Welding Joints Mixed with Duplex Steel

Słania J., Krawczyk R., Masłoń D.

Archives of Metallurgy and Materials

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2016

|

Vol. 61, iss. 1

159--168

EN

Results of the examinations of sample plates of mixed joints with the duplex steel were discussed. Examinations were taken on the sample plates of mixed joints of sheet plates type P355NL1 and X2CrNiMoN22-5-3 welded by the flux-cored wire DW-329A by the Kobelco company of the following category T 22 9 3 NL RC/M3 in the gas shroud M21 (Ar+18%CO2) (plate no.1), and nickel covered electrodes E Ni 6082 by the Böhler company (plate no. 2). Results of the side bend test of welded joint, transverse tensile test, stretching of the weld metal, impact strength, micro and macroscopic metallographic examinations, and measurements of the delta ferrite content were presented.

17

Numerical Simulation of Duplex Steel Multipass Welding

Giętka T., Ciechacki K., Kik T.

Archives of Metallurgy and Materials

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2016

|

Vol. 61, iss. 4

1975--1984

EN

Analyses based on FEM calculations have significantly changed the possibilities of determining welding strains and stresses at early stages of product design and welding technology development. Such an approach to design enables obtaining significant savings in production preparation and post-weld deformation corrections and is also important for utility properties of welded joints obtained. As a result, it is possible to make changes to a simulated process before introducing them into real production as well as to test various variants of a given solution. Numerical simulations require the combination of problems of thermal, mechanical and metallurgical analysis. The study presented involved the SYSWELD software-based analysis of GMA welded multipass butt joints made of duplex steel sheets. The analysis of the distribution of stresses and displacements were carried out for typical welding procedure as during real welding tests.

18

The effect of laser welding parameters of duplex steel on fatigue life of joints without geometric notch in the form of face and root

Sołtysiak R.

Problemy Eksploatacji

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2015

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no. 3

103--112

EN

A geometrical and a structural notch effect have the main influence on the local stress and strain concentration in the welded joints. These factors have a significant influence on the fatigue life of welded joints. This paper presents the results of the fatigue life tests of laser-welded joints of DUPLEX 2205 steel, taking into account the structural notch. The geometric notch in the form of face and root was removed. The Nd-YAG disk laser was used to weld butt joints. The welding process was conducted using two different parameters of welding without using additional material. The parameters were chosen based on previous studies (according to PN-EN ISO 15614-11:2005). In the study of the fatigue life of laser-welded joints, the geometric notch was ground out. Based on this research, the effect of welding parameters on the fatigue life was not observed. The fatigue cracks initiation and propagation occurred in the base materials in all cases. In addition, the results of the fatigue life of welded joints were related to the fatigue life of the samples taken from the parent material.

PL

W połączeniach spawanych występują lokalne spiętrzenia odkształceń spowodowane głównie geometrią złącza (karb geometryczny) jak również niejednorodnością strukturalną (karb strukturalny). Czynniki te mają znaczący wpływ na trwałość zmęczeniową złącza. W niniejszej pracy przedstawiono wyniki prób zmęczeniowych złączy spawanych laserowo ze stali typu DUPLEX 2205 z uwzględnieniem karbu strukturalnego. Karb geometryczny w postaci lica i grani spoiny usunięto. Złącza spawane czołowo wykonano przy użyciu lasera dyskowego typu Nd-YAG bez materiału dodatkowego dla dwóch różnych parametrów spawania. Parametry zostały dobrane na podstawie wcześniejszych badań (zgodnie z PN-EN ISO 15614-11: 2005) przeprowadzonych na złączach wykonanych kilkunastoma różnymi parametrami spawania. W badaniach trwałości zmęczeniowej połączeń spawanych laserowo pominięto karb geometryczny. Pozwoliło to na określenie optymalnych parametrów spawania laserowego stali typu DUPLEX 2205 ze względu na trwałość zmęczeniową powstałej podczas spawania struktury złącza. Dodatkowo otrzymane wyniki trwałości zmęczeniowych złączy spawanych odniesiono do trwałości zmęczeniowej próbek pobranych z materiału rodzimego.

19

Przykłady zastosowania stali nierdzewnych w pojazdach publicznego transportu szynowego i drogowego

Sołtysiak R.

Logistyka

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2015

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nr 3

4542--4551, CD 1

PL

Zamawiający coraz częściej w specyfikacji określa, z jakiego typu materiałów ma być wykonany pojazd, jaką ma mieć maksymalną masę, żąda co najmniej 10 letniej gwarancji ze względu na korozję poszycia. Wiodący producenci pojazdów komunikacji publicznej wychodzą na przeciw obecnym wymaganiom stawianym przez zamawiających. W pracy przeprowadzono przegląd stanu rzeczy dotyczący zastosowania stali nierdzewnej w konstrukcjach pojazdów publicznego transportu szynowego i drogowego. Praca zawiera zestawienie przykładowych pojazdów w których zastosowano konstrukcje ze stali nierdzewnej. Przegląd ten obejmuje okres od wynalezienia stali nierdzewnej do obecnych czasów. W większości przypadków podano rodzaj materiału, jaki został zastosowany w danym pojeździe. Prace zakończono podsumowaniem w którym między innymi zestawiono zalety stosowania stali nierdzewnych w konstrukcjach pojazdów publicznego transportu szynowego i drogowego.

EN

In the tender specifications the Ordering Party more often determine what type of materials must be used on the construction of the vehicle, which must be the maximum weight or demands at least a 10-year warranty against corrosion of the outer skin. Leading manufacturers of public transport vehicles go up against the current requirements of the Ordering Party. In this paper the review of the state of the use of stainless steel in the construction of vehicles of rail and road public transport were presented. The work contains a list of examples of vehicles in which the stainless steel has been used on structures. This review covers the period from the invention of the steel to the present time. As far as possible the type of material that has been applied to the vehicle was given. The work was completed summary in which, inter alia, summarizes the advantages of the use of stainless steel in the construction of the vehicles of rail and road public transport.

20

Etching techniques for duplex steels

Martínek P., Podaný P.

Journal of Achievements in Materials and Manufacturing Engineering

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2015

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Vol. 68, nr 1

11--16

EN

Purpose: This contribution describes a search for an optimum etching technique for duplex ferritic-austenitic steels which would enable metallographers to find the fractions of major phases by image analysis and determine the amounts, distributions and types of intermetallic phases. Design/methodology/approach: The microstructures were revealed by etching with seven different reagents. The phase compositions were evaluated using either image analysis or test grid-based quantitative analysis. The experimental materials were X2CrNiMoN 22-5-3 steel and its cerium-doped variant. Each of them was examined in two conditions: upon opendie forging and subsequent solution annealing and upon long-time annealing, where the latter led to extensive precipitation of intermetallic phases. The fractions of major and intermetallic phases were also determined using EBSD. Both quantitative and qualitative EBSD data were then compared to the values obtained using optical microscopy. Findings: In X2CrNiMoN 22-5-3 duplex steel, the microstructure can be revealed using various reagents and both chemical and electrochemical etching. The differences between the reagents, when used for evaluating the amounts of major phases (austenite + ferrite), were not substantial. The fraction of sigma phase in long-time-annealed samples can be evaluated using image analysis only if etched with NaOH solution or NH4OH. These etchants also effectively reveal carbides on grain boundaries. However, the values obtained with NaOH are overestimated. When the other reagents are used, the evaluation must be done using another method (e.g. grid-based quantitative analysis). Sigma phase proportions found by optical microscopy are higher than those measured using EBSD. In order to identify microstructural variations across the forged parts, specimens were taken from three locations (centre, ¼ , edge). The sigma phase amounts found in all three testing locations of the sample of the cerium-doped duplex steel were higher than the corresponding amounts in the cerium-free sample. In both materials, the amounts of sigma phase are higher in the centre of the sample than near the edge. This difference is more significant in the ceriumfree material. Originality/value: The article is devoted to phase content evaluation in duplex steels by different methods. EBSD and image analysis of micrographs were compared. Micrographs were acquired by light microscopy after microstructure revelation by various etchants. The content of ferrite, austenite and intermetallic phases was evaluated.