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1

Use of a Toroidal Nozzle for Welding Duplex Stainless Steel

Giętka Tomasz, Trepczyńska-Łent Małgorzata

Advances in Science and Technology. Research Journal

|

2024

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Vol. 18, no 6

227--246

EN

The goal of this research was to determine the appropriate parameters for welding two-phase duplex stainless steel (DSS) and to understand the challenges involved in the process. For welding pipes with diameters of ø25 mm and ø38 mm of steel type 1.4462, the classic tungsten inert gas (TIG) method and TIG with a toroidal shielding gas nozzle were used. The aim was to improve the durability and service life of welded joints produced using the toroidal shielding gas nozzle compared to those produced using traditional TIG methods for DSS welding. The welding process was carried out using the parameters: arc voltage 9V, welding current 105A for TIG and 80A with a toroidal shielding gas, welding speed 90 mm/min for TIG and 95 mm/min with a toroidal shielding gas. The welded elements were tested for quality properties. Tests such as visual, penetration, radiographic, and destructive tests (macroscopic, ferrite content, hardness, microscopic, diffraction, static strength, and fatigue) were conducted on the test samples prepared in the TIG process. The actual test results were compared to the acceptable values from the standards. Using a toroidal nozzle in the welding process had lowered the ferrite content in the surface layers by about 10% in comparison to the traditional TIG method. The morphology and phase arrangement of the tested welded joints varied significantly, even when utilizing a toroidal nozzle. The analysis of the determined durability showed that welding with a toroidal shielding gas nozzle provided superior results, with enhancements ranging from 4% to 132%. Furthermore, the use of a toroidal nozzle reduced gas consumption by 17% for each joint type compared to conventional welding. In terms of service life, the joints welded with a toroidal nozzle demonstrated nearly twice the longevity of those welded with traditional methods.

2

Shielding gas oxygen and nitrogen content effects in the case of duplex stainless steel welding

Varbai Balázs

Advances in Materials Science

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2024

|

Vol. 24, nr 3(81)

111--123

EN

The duplex stainless steels show improved localized corrosion resistance and strength comparing to the austenitic stainless steels. All of the duplex stainless steels solidify as pure ferrite and the double microstructure is evolving during the solid-state, diffusion driven phase transformation. In this research nitrogen and oxygen containing argon-based shielding gases were used. It was found that the nitrogen and oxygen addition significantly increased the weld metal austenite content, up to +27%. The oxygen addition also improved the weld dissolved oxygen content with up to +0.09%, and the weld penetration depth with up to +3.3 mm.

3

Influence of Aging Time at 850°C on Microstructure and Corrosion Resistance of a Cold Rolled 2205 Duplex Stainless Steel

Assumpção Raphael França, Fortes Monteiro Jessica C., Campideli Victor Cardoso, Santos Dagoberto, Sicupira Dalila C.

Archives of Metallurgy and Materials

|

2023

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Vol. 68, iss. 2

681--688

EN

The effect of aging time at 850°C for 300 s, 600 s, 1800 s, and 84600 s on the microstructural evolution and corrosion resistance of 2205 duplex stainless steel (DSS) was studied after cold rolling up to 60% of reduction. X-ray diffraction, scanning electron and transmission electron microscopy were used for microstructural characterization. The corrosion behavior was studied by cyclic potentiodynamic polarization (CPP) and electrochemical impedance technique (EIS) in 3.5% NaCl solution and the susceptibility to sensitization was investigated through the double loop electrochemical potentiodynamic reactivation (DL-EPR) test in 0.5 M H2SO4 + 0.1 M NaCl + 0.002 M KSCN solution. After cold working, increasing aging time led to an increase in sigma phase precipitation and a decrease in pitting corrosion resistance. However, the ultrafine microstructure had a beneficial influence on the self-healing effect in Cr and Mo depleted areas with the increasing of aging time, resulting in higher passivation ability. The DSS 2205 type was not susceptible to intergranular corrosion for the aged conditions applied.

4

Microstructure formation and fatigue performance of duplex stainless steel 2205 welded joints by electric resistance welding

Dong Zhilong, Xie Xue-fang, Li Jingwen, Wan Yu, Wang Chaolei

Archives of Civil and Mechanical Engineering

|

2023

|

Vol. 23, no. 3

art. no. e180, 2023

EN

The electric resistance welding of thin-thickness duplex stainless steel (DSS) has an outstanding attraction in the plate-fin heat exchanger which is widely used in power machinery, diesel locomotive and other fields, but its structural integrity is threatened seriously by fatigue failure. Therefore, in this research, the formation of the heterogeneous microstructure of DSS electric resistance welding joints (ERWJ) was analyzed by the optical microscope (OM) and electron back-scattered diffraction (EBSD) observations, and the uniaxial tensile and fatigue tests were subsequently executed to disclose their mechanical properties. The intrinsic relevancy between phase-related characteristics and failure behavior was extensively analyzed. The results show that the ferrite was dominating at whole ERWJ, particularly at the energized area, accounting for up to 72%. More than 45% of high-angle boundaries (HABS) and the highest kernel average misorientation (KAM, 2.46° for austenite and 1.52° for ferrite), which indicates greater plastic deformation and residual stress, were observed at the weld edge. In addition, the failure occurred as a tear along the weld edge regardless of the monotonic and cyclic loadings under the deterioration of residual stress and island-like austenite. The distribution of fatigue life with cyclic amplitude performed an obvious turning point of 19.5 MPa due to the different failure mechanisms, providing a permissible range of the stress amplitudes and reinforcement strategies for the plate-shell heat exchanger ERWJ in the engineering.

5

Effect of Shielding Gas Composition on Geometry and Austenite Formation in Low Power Pulsed Nd:YAG Laser Welded 2205 Duplex Stainless Steel

Gozarganji Hajibaba, E., Farnia A., Ebrahimnia M.

Archives of Metallurgy and Materials

|

2021

|

Vol. 66, iss. 1

187--195

EN

This paper presents an investigation into effect of nitrogen content of shielding gas mixture on weld geometry, microstructure and hardness of pulsed laser welded 2205 duplex stainless steel. Full penetration autogenous welding was performed on 2 mm thick plates using a low power pulsed Nd: YAG laser. light and scanning electron microscopy were used to study the resulting microstructures. It is observed that 2 mm full penetrated joint decreases to 1.8 mm by dominating nitrogen in argon-nitrogen mixture. Different morphologies of austenite phase as well as an increase of 8% of its content can be observed in pure nitrogen shielded welds. Average weld grain size in sample which is welded in nitrogen atmosphere stands at approximately 41 μm which is smallerthan that of argon atmosphere which is about 51 μm. Micro-hardness test reveals that hardness values increase from 280 HV in base metal to 307 HV in weld center line and the shielding gas mixture does not significantly influence the weld hardness.

6

Badania prądami wirowymi połączeń spawanych – wpływ doboru warunków i parametrów badania na czułość i wiarygodność metody – przykłady zastosowań

Wocial Adam

Badania Nieniszczące i Diagnostyka

|

2019

|

nr 4

29--34

EN

The article presents a practical approach in the application of the eddy current method in cases outside the scope and recommendations of EN/ISO 17643: 2015 [1] regarding the testing of eddy currents of welded joints. This standard does not explicitly limit the scope of application to specific materials and welding methods, but gives e.g. recommendations regarding calibration standards, probe construction and test parameters. Such a situation may cause misunderstanding and a number of wrong decisions affecting the result of the examination. The article gives several examples of eddy current testing of welded joints where a completely new approach was required that went far beyond the aforementioned standard, e.g. testing of aluminum welds, duplex steel, metallic coatings, and electron beam welding.

PL

W artykule zaprezentowane jest praktyczne podejście w zastosowaniu metody prądów wirowych w przypadkach wykraczających poza zakres i zalecenia normy EN ISO 17643: 2015[1] dotyczącej badania prądami wirowymi połączeń spawanych. Norma ta nie ogranicza wyraźnie zakresu stosowania do konkretnych materiałów i metod spawania, natomiast podaje np. zalecenia dotyczące wzorców kalibracyjnych, budowy sond i parametrów badania. Sytuacja taka może powodować niezrozumienie i szereg błędnych decyzji wpływających na wynik badania. W artykule podano kilka przykładów badania prądami wirowymi połączeń spawanych, gdzie wymagane było zupełnie nowe podejście wykraczające daleko poza wspomnianą normę jak np. badanie spoin stali duplex, aluminium, badania poprzez powłoki metaliczne czy np. spawanie wiązką elektronów.

7

Effect of Y2O3 Nanoparticles on Corrosion Study of Spark Plasma Sintered Duplex and Ferritic Stainless Steel Samples by Linear Sweep Voltammetric Method

Shashanka R., Chaira D., Kumara Swamy B. E.

Archives of Metallurgy and Materials

|

2018

|

Vol. 63, iss. 2

749--763

EN

The microstructure and corrosion properties of spark plasma sintered yttria dispersed and yttria free duplex and ferritic stainless samples were studied. Spark plasma sintering (SPS) was carried out at 1000°C by applying 50 MPa pressure with holding time of 5 minutes. Linear sweep voltammetry (LSV) tests were employed to evaluate pitting corrosion resistance of the samples. Corrosion studies were carried out in 0.5, 1 and 2 M concentration of NaCl and H2SO4solutions at different quiet time of 2, 4, 6, 8 and 10 seconds. Yttria dispersed stainless steel samples show more resistance to corrosion than yttria free stainless steel samples. Pitting potential decreases with increase in reaction time from 2 to 10 seconds. Similarly, as concentration of NaCl and H2SO4 increases from 0.5 M to 2 M the corrosion resistance decrements due to the availability of more Cl¯ and SO42¯ ions at higher concentration.

8

Effect of ageing time on microstructure and mechanical properties of SAF 2205 duplex stainless steel

Penha R. N., Silva L. B., Mendonça C. S. P., Moreira T. C., Melo M .L. N. M.

Archives of Materials Science and Engineering

|

2018

|

Vol. 91, nr 1

23--30

EN

Purpose: The aim of this study was to present the influence of mass concentration of the reinforcement phase on the structure and optical properties of the obtained composite thin films with a polymer matrix reinforced by SiO2, TiO2 and Bi2O3 nanoparticles, produced by the spin-coating method. Design/methodology/approach: To produce composite materials, 10% wt. polymer solutions of polyacrylonitrile (PAN) and N, N - Dimethyloformamide (DMF) were used, containing nanoparticles with a mass concentration ratio of, sequentially: 0, 4, 8, 12%. The morphology, structure and chemical composition of the obtained thin films were determined on the basis of surface topography images, taken using atomic force microscopy (AFM) and a scanning electron microscope (SEM) with EDX and QBSD spectrometers. In order to analyse the optical properties, UV-Visible spectroscopy (UV-Vis) was used. The width of the band gap was determined on the basis of the absorption spectra of radiation (UV-Vis). Findings: The carried out morphology and surface structure research showed that with increasing mass increased porosity of the produced coating surface was observed. In addition, the greater the diameter of the applied ceramic nanoparticles, the more noticeable this effect was. The analysis of the optical properties of the obtained nanomaterials, carried out based on the registered spectra in absorption function of the wavelength, revealed a strong absorption of this type of layers under ultraviolet radiation. Research limitations/implications: The nanostructured materials as components provides nanocomposite optical properties, such as absorption and width of the energy gap. In addition, nanoparticle content causes changes of the surface morphology, which is an important parameter of thin films in potential applications. Originality/value: The properties of films depend not only on the individual components used, but also on the morphology and the interfacial characteristics.

9

Dry Sliding Wear Behavior of Super Duplex Stainless Steel AISI 2507: A Statistical Approach

Davanageri M., Narendranath S., Kadoli R.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 4

47--56

EN

The dry sliding wear behavior of heat-treated super duplex stainless steel AISI 2507 was examined by taking pin-on-disc type of wear-test rig. Independent parameters, namely applied load, sliding distance, and sliding speed, influence mainly the wear rate of super duplex stainless steel. The said material was heat treated to a temperature of 850°C for 1 hour followed by water quenching. The heat treatment was carried out to precipitate the secondary sigma phase formation. Experiments were conducted to study the influence of independent parameters set at three factor levels using the L27 orthogonal array of the Taguchi experimental design on the wear rate. Statistical significance of both individual and combined factor effects was determined for specific wear rate. Surface plots were drawn to explain the behavior of independent variables on the measured wear rate. Statistically, the models were validated using the analysis of variance test. Multiple non-linear regression equations were derived for wear rate expressed as non-linear functions of independent variables. Further, the prediction accuracy of the developed regression equation was tested with the actual experiments. The independent parameters responsible for the desired minimum wear rate were determined by using the desirability function approach. The worn-out surface characteristics obtained for the minimum wear rate was examined using the scanning electron microscope. The desired smooth surface was obtained for the determined optimal condition by desirability function approach.

10

The effect of wet underwater welding on cold cracking susceptibility of duplex stainless steel

Łabanowski J., Prokop-Strzelczyńska K., Rogalski G., Fydrych D.

Advances in Materials Science

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2016

|

Vol. 16, nr 2(48)

68--77

EN

The present work was conducted to assess the weldability of duplex stainless steel in underwater conditions. Metal manual arc welding (MMA) with the use of coated electrodes was used in the investigations. Tekken weldability tests were performed underwater at 0.5 m depth and in the air. Nondestructive tests, metallographic examinations of welds, ferrite content assessment in microstructure and hardness test were performed. The good weldability at underwater conditions of duplex stainless with the use of MMA method was confirmed, however difficulties in stable arc burning were revealed.

11

Determination of tool life and research wear during duplex stainless steel turning

Krolczyk G. M., Nieslony P., Legutko S.

Archives of Civil and Mechanical Engineering

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2015

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Vol. 15, no. 2

347--354

EN

The purpose of the study is to determine the coated carbides tool life and the tool point surface topography. The study determined the cutting conditions in the process of turning duplex stainless steel (DSS), and detailed identification of wear mechanisms occurring on the rake face and major flank. The results of wear occurring on both tool points were compared with the width of the flank wear in relation to the period of the steady-state wear of the tool point. Occurrences of various mechanisms have been proven, such as abrasive wear and adhesion wear. Where machining without the use of a cooling lubricant occurred, longer tool life has been determined as well as a greater resistance to abrasive wear of the tools which were coated with Al2O3. Scanning electron microscopy (SEM) has been used for the wear analysis.

12

Effect of microstructure on mechanical properties and corrosion resistance of 2205 duplex stainless steel

Łabanowski J., Świerczyńska A., Topolska S.

Polish Maritime Research

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2014

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nr 4

108--112

EN

This paper presents results of the research on impact of microstructure of austenitic-ferritic steel of duplex type on its mechanical properties and susceptibility to stress corrosion cracking. As showed, improper processing technologies more and more often used in shipbuilding industry for plates and other half-finished products made of duplex steel may cause significant lowering their properties, which frequently makes their replacing necessary. Results of the tests on stress corrosion under tension with low strain rate (SSRT) conducted in an inert and corrosion (boiling magnesium chloride) environment , are presented. It was proved that even minor structural transformations taking place in 500ºC ageing temperature lower corrosion resistance of the steel. Structural transformations occurring in 700ºC temperature to a smaller extent influence susceptibility to stress corrosion of the steel, however they cause drastic drop in its plasticity.

13

The effect of silicon content on the pitting corrosion of duplex stainless steel weldment

Lee B.H., Lee H.J., Kang D.W., Lee H.W.

Archives of Materials Science and Engineering

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2014

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Vol. 67, nr 2

60--69

EN

In this study, the effect of Si content at a welded DSS on the pitting resistance was investigated. Design/methodology/approach: The δ-ferrite fraction increased due to addition of Si, and the amount of γ2 decreased. In the ferric chloride pitting test, the weight reduction range decreased due to an increase in the Si content. As to the location, pittings occurred intensively at the grain boundary or within the austenite grain due to the difference in PREN caused by the differential solid solubility in each phase. Findings: As a result of the potentiodynamic polarization test, while the Epit(Critical Pitting Potential) of all specimens depending on the temperature were observed to be similar at froom temperature up to 45°C, the reduction range of the Epit was found to be small at the temperature higher than 45°C as Si content increased. This was found to be because of formation of SiO2 in the passive film. Research limitations/implications: Higher the addition of Si, the more the number of pittings generated at the grain boundary decreased as the coherence of the passive film increased by the Si accumulated at the boundary. Originality/value: In this study, we intend to investigate the effect of Si element addition on the pitting resistance of the duplex stainless steel welding zone.

14

Studies on pitting corrosion of 2205 duplex stainless steel induced by sulphate reducing bacteria

Michalska J., Jaworska-Kik M., Dzierżewicz Z.

Ochrona przed Korozją

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2013

|

nr 6

250--253

EN

Sulphate-reducing bacteria (SRB) are predominant microorganisms involved in microbiologically influenced corrosion (MIC) of stainless steels. Metabolic production of hydrogen sulphide by SRB leads to formation of sulphides ions which significantly influence the anodic and cathodic processes and ultimately enhances the corrosion of materials. This phenomenon can be especially harmful to highly alloyed steels. The paper presents the results on microbiologically influenced corrosion (MIC) induced by pure SRB strains on 2205 duplex stainless steel (DSS). In the present study, steel coupons were exposed to SRB of Desulfovibrio desulfuricans species. Biofilm formed on 2205 DSS caused the seeming ”ennoblement” of the metal surface, which resulted in an increase of corrosion potential. Electrochemical polarization studies performed on samples covered with biofilm revealed that bacteria presence in corrosive medium may increase the metal susceptibility to pitting. However, a slight decrease in pitting and repassivation potential values were observed after 30 days. The SRB-influenced attack is initiatedby selective etching at locations of lower chromium and molybdenum contents. Therefore, the austenite phase was found to be more susceptible to MIC induced by SRB.

PL

Bakterie redukujące siarczany (BRS) stanowią dominującą grupę mikroorganizmów wywołujących korozję mikrobiologiczną w stalach odpornych na korozję. Tworzenie siarkowodoru w wyniku aktywności metabolicznej BRS wyraźnie wpływa na przebieg procesów katodowych i anodowych, zwiększając ostatecznie szybkość korozji materiałów. Zjawisko to może być szczególnie niebezpieczne dla stali wysokostopowych. Artykuł przedstawia wyniki badań korozji mikrobiologicznej wywołanej przez czyste szczepy BRS w stali duplex 2205. W niniejszej pracy próbki stali poddano testom ekspozycyjnym w środowisku zawierającym BRS z gatunku Desulfovibrio desulfuricans. Biofilm BRS utworzony na stali powodował pozorne „uszlachetnienie” stali, czego skutkiem był wzrost potencjału korozyjnego. Badania elektrochemiczne na próbkach pokrytych biofilmem wykazały, że ekspozycja w środowisku BRS może prowadzić do rozwoju korozji wżerowej stali. Jednakże zmiany wartości potencjału korozji wżerowej i potencjału repasywacji były obserwowane dopiero po 30 dniach. Zniszczenia korozyjne inicjowane przez BRS miały charakter lokalny. Obserwowano selektywne trawienie obszarów o niższej zawartości chromu i molibdenu, czym wykazano, że austenit jest fazą bardziej podatną na rozwój korozji wżerowej wywołanej aktywnością metaboliczną BRS.

15

Identyfikacja korozji międzykrystalicznej za pomocą elektrochemicznej potencjokinetycznej reaktywacji : optymalizacja warunków

Wawrzaszek U., Masalski J.

Ochrona przed Korozją

|

2013

|

nr 7

292--297

PL

W pracy podjęto próbę doboru odpowiedniego roztworu i warunków do identyfikacji stopnia uczulenia dla stali dupleksowej typu EN 1.4462 za pomocą metody bicyklicznej elektrochemicznej potencjokinetycznej reaktywacji (ang. double – loop electrochemical potentiokinetic reactivation test DL –EPR). Badany materiał został poddany procesowi przesycania, a następnie uczulania w temperaturze 720°C w czasie 168 godzin. Do badań użyto roztworu testowego w skład którego wchodził H2SO4 ( 0,1÷2,5 M) oraz NH4SCN (0,1÷0,5 M). Pomiary były prowadzone w temperaturze otoczenia przy szybkości skanowania od 1,67 do 3,00 mV/s. Stopień uczulenia wyznaczono na podstawie gęstości prądów (SU,I) przez określenie stosunku maksymalnej gęstości prądu skanowania reaktywacyjnego (Ir) do maksymalnej gęstości prądu skanowania aktywacyjnego (Ia). Najwyższą wartość SU,I odnotowano dla roztworu 2,5 M H2SO4 + 0,5 M NH4SCN; wynosiła ona 50%.

EN

The objective of the study was to find a suitable solution and optimal conditions for the identification of the degree of sensitisation of duplex steel type EN 1.4462 by means of the double - loop electrochemical Potentiokinetic reactivation (DL – EPR) test. The test material was first annealed and then sensitized at 720°C for 168 hours. Test solutions containing H2SO4 (0.1÷2.5 M) and NH4SCN (0.1÷0.5 M) were used. Measurements were conducted at ambient temperature with a scan rate of 1.67÷3.00 mV/s. The degree of sensitization was determined based on the current density (SU,I) by means of establishing the ratio between maximum reactivation current density (Ir) and maximum activation current density (Ia). The highest SU,I value (50%) was observed in a solution containing 2.5 M H2SO4+ 0.5 M NH4SCN.

16

Predicting the tool life in the dry machining of duplex stainless steel

Królczyk G., Gajek M., Legutko S.

Eksploatacja i Niezawodność

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2013

|

Vol. 15, no. 1

62-65

EN

This paper examines the influence of cutting parameters, namely cutting speed, feed and depth of cut onto tool life in DSS turning process. The study included developing a mathematical model to determine the tool life. Verification research has been carried out on CNC lathe, hence the test plan has been adjusted to the possibility of programmable machines controlling GE Fanuc series 0 - T. The comparison of results obtained by given experimental plan was performed in industrial company.

PL

W artykule przedstawiono wpływ parametrów obróbki, a mianowicie prędkości skrawania, posuwu i głębokości skrawania na okres trwałości ostrza w procesie toczenia stali duplex. Badania obejmowały opracowanie modelu matematycznego dla określenia okresu trwałości ostrza skrawającego. Badania weryfikacyjne wykonywano na tokarce sterowanej numerycznie, stąd plan badań dostosowany został do możliwości programowych maszyny ze sterowaniem GE Fanuc seria 0 - T. Porównanie wyników przeprowadzono w warunkach produkcyjnych.

17

Deformation of ferrite-austenite banded structure in cold-rolled duplex steel

Ryś J., Zielińska-Lipiec A.

Archives of Metallurgy and Materials

|

2012

|

Vol. 57, iss. 4

1042-1053

EN

Duplex type ferritic-austenitic stainless steels develop a specific two-phase banded structure upon thermo-mechanical pre-treatment and subsequent cold-rolling. The band-like morphology of ferrite and austenite imposes different conditions on plastic deformation of both constituent phases in comparison to one-phase ferritic and austenitic steels. In the present research the ingot of a model ferritic-austenitic steel of duplex type, produced by laboratory melt, was subjected to preliminary thermo-mechanical treatment including forging and solution annealing. Afterwards cold-rolling was conducted over a wide deformation range. The investigations comprised examination of ferrite and austenite microstructures by means of optical and transmission electron microscopy and texture measurements after selected rolling reductions. The presented results indicate that deformation mechanisms operating within the bands of both constituent phases are essentially the same as compared to one-phase steels, however their appearance and contribution are changed upon deformation of two-phase banded structure. Different deformation behavior within ferrite-austenite bands in duplex steels, visible especially at higher strains, considerably affects microstructure evolution and in consequence texture formation in both phases.

PL

Podczas wstępnej obróbki cieplno-plastycznej i dalszego walcowania na zimno w nierdzewnych stalach ferrytyczno-austenitycznych typu duplex następuje rozwój charakterystycznej pasmowej struktury dwufazowej. Pasmowa morfologia ferrytu i austenitu stwarza odmienne warunki dla procesu odkształcenia plastycznego obu składowych faz w porównaniu do jednofazowych stali ferrytycznych i austenitycznych. W prezentowanych badaniach wlewek modelowej stali ferrytyczno-austenitycznej typu duplex, uzyskany na drodze wytopu laboratoryjnego, poddano wstępnej obróbce cieplno-plastycznej obejmującej kucie na gorąco i przesycanie. Następnie przeprowadzono walcowanie na zimno w szerokim zakresie deformacji. Badania obejmowały obserwacje mikrostruktury ferrytu i austenitu za pomocą mikroskopii optycznej i transmisyjnej mikroskopii elektronowej oraz pomiary tekstury po wybranych stopniach odkształcenia. Prezentowane wyniki wskazują, ze mechanizmy odkształcenia działające w obszarach obu składowych faz są zasadniczo takie same jak w przypadku stali jednofazowych, jednakże ich udział i znaczenie ulegają istotnym zmianom podczas odkształcenia pasmowej struktury dwufazowej. Odmienny sposób odkształcenia pasm ferrytu i austenitu w stalach duplex, widoczny zwłaszcza w zakresie większych odkształceń, wpływa w istotny sposób na rozwój mikrostruktury a w konsekwencji na tworzenie się tekstury w obu fazach.

18

Passivity of duplex stainless steels after long-term ageing in 0.5 M NaCl at 50 [grades]C

Zhang H., Vignal V., Heintz O., Peultier J.

Ochrona przed Korozją

|

2011

|

nr 7

472-474

EN

The influence of long-term ageing in NaCl on the passivity and the electrochemical behaviour of UNS S32304 is studied. The passive film thickness, the Cr/Fe ratio and the chloride content were significantly increased after ageing. The chloride distribution depends on residual stresses, sample microstructure and surface preparation.

PL

W pracy badano wpływ długiego czasu starzenia w roztworze NaCl na pasywację i elektrochemiczne zachowanie się stali UNS S32304. Wykazano, że po długim czasie starzenia znacząco wzrasta grubość warstwy pasywnej, stosunek Cr/Fe i zawartość chlorków. Rozkład zawartości chlorków zależy od rozkładu naprężeń szczątkowych, mikrostruktury i przygotowania powierzchni.

19

Passive properties of duplex stainless steels after long-time ageing in air

Krawiec H., Vignal V., Heintz O., Peultier J., Mainy D.

Ochrona przed Korozją

|

2010

|

nr 11

516-520

EN

The influence of long-term ageing in air on the chemical composition of passive films and the electrochemical behaviour of samples was investigated. After mechanical polishing, there is no significant influence of the grain orientation. The passive film thickness is around 1.8 and 2.3 nm the ferrite and the austenite, respectively. The ratio Cr/Fe in the passive film is 0.48 and 0.37 in the ferrite and the austenite, respectively. The behaviour of both phases behave can be described by the CPE. After long-term ageing, the passive film thickness and the ratio Cr/Fe was not significantly affected. By contrast, LEIS diagrams were significantly different than after mechanical polishing. Two capacitive loops were detected in the ferrite phase associated with the passive film and interface. The grain orientation had significant influence on the electrochemical behaviour of the ferrite phase after long-term ageing. On the other hand, the austenite behaves like a blocking electrode represented by the Randles circuit.

PL

W pracy przedstawiono wpływ starzenia w powietrzu stali duplex UNS S32304 na jej elektrochemiczne zachowanie się i skład chemiczny warstwy pasywnej. Wykazano, że orientacja krystalograficzna ziaren nie miała istotnego wpływu na elektrochemiczne zachowanie się stali niestarzonej. Grubość warstwy pasywnej utworzonej na ferrycie była 1,8 nm, natomiast na austenicie 2,3 nm. Z kolei stosunek Cr/Fe dla ferrytu wynosił 0,48, a dla austenitu 0,37. Starzenie próbek stali duplex w powietrzu przez 1 rok nie wpłynęło istotnie na grubość warstwy pasywnej ani na stosunek Cr/Fe. Lokalne badania impedancyjne wykonane dla ferrytu wykazywały obecność dwu pojemnościowych półokręgów, których nie obserwowano dla próbek niestarzonych. Ponadto wykazano, że orientacja krystalograficzna ziaren ma wpływ na elektrochemiczne zachowanie się stopu starzonego. Za pomocą badań LEIS wykazano, że ziarna austenitu zachowują się jak elektroda blokująca.

20

Lutowanie próżniowe elementów kół wirnika ze stali duplex

Bielanik J.

Obróbka Metalu

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2010

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nr 3

18--23