Corrosion Behaviour of a Laser-MIG hybrid welding-brazing Joint of 6061 Aluminium Alloy to SUS304 Stainless Steel

CORROSION ◽  
10.5006/3866 ◽  
2021 ◽  
Author(s):  
ruilin liu ◽  
Yunqi Liu ◽  
Zheng Lei ◽  
Hui Tang ◽  
Shaoxiong He ◽  
...  

Lightweight steel-aluminium structures have broad application prospects because of their lowering weight characteristics, however, the corrosion of welding-brazing joints in steel-aluminium structures is less concerned or studied. In this paper, the corrosion behaviour of the Laser-MIG hybrid welding-brazing joints of steel-aluminium is investigated through the tests and analysis of salt spray, immersion and electrochemistry. The salt spray and immersion tests show that obvious galvanic corrosion occurs at the welded joints, in which the aluminium side is seriously corroded while the steel side is not corroded. The OCP values of the aluminium alloy and the weld metal are similar (approximately -0.48 V), and the stainless steel has a higher OCP value of -0.33 V. The corrosion resistance of the weld metal is lower than aluminium- as well as steel-base materials. The corrosion resistance of the joints is controlled by the aluminium alloy part of the two metals based on the open-circuit potential and EIS analysis. A possible corrosion process schematic for the physical/chemical properties of a welding-brazing joint immersed in a sodium chloride solution is proposed according to electrochemical impedance spectroscopy.

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2177 ◽  
Author(s):  
Andrey Gnedenkov ◽  
Sergey Sinebryukhov ◽  
Dmitry Mashtalyar ◽  
Igor Vyaliy ◽  
Vladimir Egorkin ◽  
...  

The high electrochemical activity of the aircraft 1579 aluminium alloy with a welded joint and the necessity of the coating formation to protect this material against corrosion as well as to increase the stability of the weld interface in the corrosive medium has been previously established. In this work, two suggested methods of protective coating formation based on plasma electrolytic oxidation (PEO) in tartrate-fluoride electrolyte significantly increased the protective properties of the welded joint area of the 1579 Al alloy. The electrochemical properties of the formed surface layers have been investigated using SVET (scanning vibrating electrode technique) and SIET (scanning ion-selective electrode technique), EIS (electrochemical impedance spectroscopy), OCP (open circuit potential), and PDP (potentiodynamic polarization) in 0.5 M NaCl. The less expressed character of the local electrochemical processes on the welded 1579 Al alloy with the composite coating in comparison with the base PEO-layer has been established. Polymer-containing coatings obtained using superdispersed polytetrafluoroethylene (SPTFE) treatment are characterized by the best possible protective properties and prevent the material from corrosion destruction. Single SPTFE treatment enables one to increase PEO-layer protection by 5.5 times. The results of this study indicate that SVET and SIET are promising to characterize and to compare corrosion behaviour of coated and uncoated samples with a welded joint in chloride-containing media.


2008 ◽  
Vol 59 (9) ◽  
Author(s):  
Daniel Mareci ◽  
Igor Cretescu ◽  
Neculai Aelenei ◽  
Julia Claudia Mirza Rosca

The electrochemical behavior of a three Ag-Pd alloys used in dental prosthetics construction for crowns and bridges was studied in artificial saliva using the polarization curves and electrochemical impedance spectroscopy (EIS). The corrosion resistance was evaluated by means of the corrosion currents value and by coulometric analysis. The open circuit potential of Ag-Pd are attributed to dealloying followed by surface enrichment with Ag and the possible formation of an insoluble AgCl surface film on the respective alloy surfaces. Our results have shown that these alloys have a somewhat good corrosion resistance in artificial saliva. When increasing the content of Cu, corrosion resistance decreases. The passivation of all samples occurred spontaneously at the open circuit potential. The electrochemical properties of the spontaneously passivated electrodes at the open circuit potential were studied by EIS. The polarization resistance (Rp) and the electrode capacitance (Cdl) were determined. The polarisation resistance of all the samples increases with the immersion time. The polarization resistances are largest and decrease when increasing the content of Cu. Cu reduces the Ag-Pd alloy corrosion resistance. The present study, thought limited, has shown that electrochemical characteristics can be use to identify such alloys. Knowledge of the in vitro corrosion behaviour of these alloys may lead to better understanding of any biologically adverse effects in vitro.


Author(s):  
Abeens M ◽  
R Murugananthan

Abstract As AA 7075 T651 comprehensively is used in the marine naval vessels, the factor of corrosion performance always plays a significant role. In this work, an investigation is carried out to study the effect of corrosion behaviour of shot peened AA 7075 T651 in 3.5% solution. From the potentiodynamic polarization study, a 27.72% decrease is ascertained in the Icorr in shot peened specimen in correlation to unpeened aluminium alloy. A drop in Icorr from 1.883 to 1.480 mA/cm2 in shot peened specimen, indicates enhanced pitting corrosion resistance. An electrochemical impedance spectroscopy reveals a surge in the oxide layer formation on the peened surface aiding the drop in corrosion rate. Resistance to pit formations and improvement in oxygen deposition in the peened specimen is observed availing a Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray analysis (EDX). The micro structures of the peened and unpeened specimen are captured using optical microscopy and Transmission electron microscopy (TEM). Micro-strain, dislocation density is also calculated from the X- ray diffraction analysis (XRD), in which grain size reduces by 28.07%, dislocation density surges by 38.65% and micro strain increases by 21.95% in peened specimen in correlation to unpeened AA 7075 T651, resulting in a surge in corrosion resistance by 27.92% in the peened specimen in correlation to unpeened aluminium alloy.


2015 ◽  
Vol 9 (11) ◽  
pp. 119 ◽  
Author(s):  
W. A. Ghanem ◽  
W. A. Hussein ◽  
S. N. Saeed ◽  
S. M. Bader ◽  
R. M. Abou Shahba

The effect of partial replacement of nickel with nitrogen on the corrosion resistance of newly designed austenitic stainless steel samples without and with heat treated was investigated in 3.5wt% and 5wt% NaCl solution using open-circuit, potentiodynamic, cyclic anodic polarization and electrochemical impedance spectroscopy techniques. The results showed that, passivation in sample 1 where the highest addition of nickel and low addition of nitrogen is different from that for sample 4 where the nitrogen is greatest and the nickel is reduced almost to the third comparing sample 1. The difference in responses of heat treated samples to localized and general corrosion could be attributed to the difference in their phase compositions. The appearance of ferrite phase for samples (2, 4, 5 and 6) after heat treatment resulted in lowering the general and localized corrosion resistance than as forged samples in contrast with samples 1 and 3, where they still pure austenite. The obtained results are confirmed by surface examination.


2016 ◽  
Vol 710 ◽  
pp. 216-221 ◽  
Author(s):  
Wagner Izaltino Alves Dos Santos ◽  
Isolda Costa ◽  
Célia Regina Tomachuk

New treatments for replacement of chromate require lower toxicity and corrosion protection. This study aims to investigate the influence of the combination of a Ce conversion coating (CCCe) with glycol molecules on the corrosion resistance of the AA2024-T3 clad (AA1230). The corrosion resistance of surface treated and untreated samples was evaluated by electrochemical techniques (electrochemical impedance spectroscopy, polarization tests and open circuit potential). These tests were complemented by salt spray tests to accelerate the corrosive effects of weathering. The surfaces were analyzed after corrosion tests by scanning electron microscopy with X-ray energy dispersive detector (SEM - EDX). The results of the CCCe samples in combination with glycol were compared with that of the surface with chromate layer and the results showed that the CCCe treatment is a candidate for replacement of chromating with the advantage that it does not generate toxic residues. The self-healing capacity of the new treatment tested was indicated by the increased formation of corrosion products deposition on top of Fe rich intermetallis in the AA1230 clad with time of exposure to the electrolyte.


Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7730
Author(s):  
Liang Yu ◽  
Shuangshuang Hao ◽  
Xiaodong Nong ◽  
Xiuling Cao ◽  
Chen Zhang ◽  
...  

Interface problems and the destruction of the continuity of the oxide film in the Al matrix usually reduce the corrosion resistance of the material. In this paper, the corrosion resistance of Al matrix composites (AMCs) was improved by introducing the silicon carbide skeletons (SiC3D) obtained with polymer replica technology. SiC3D/6061Al was fabricated by infiltrating molten 6061Al alloy in the oxidized SiC3D using the low-pressure casting method. The corrosion resistance performances of 6061Al and SiC3D/6061Al in NaCl solution were studied by electrochemical, neutral salt spray corrosion (NSS), and salt leaching (SL) tests. Results show corrosion resistance of SiC3D/6061Al is higher than that of 6061Al alloys by open circuit potential (OCP), potentio-dynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) tests. However, NSS and SL tests show the corrosion resistance of SiC3D/6061Al is lower than that of 6061Al alloy. The reason is a corrosion resistant and anti-oxidation network macrostructure with large interface recombination, few concentrated interfaces, and a small specific area that formed in SiC3D/6061Al. SiC3D cannot damage the continuity of the Al2O3 passivating film, and the network macrostructure greatly improves the corrosion resistance performance.


Coatings ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 521 ◽  
Author(s):  
Citlalli Gaona-Tiburcio ◽  
Marvin Montoya-Rangel ◽  
José A. Cabral-Miramontes ◽  
Francisco Estupiñan-López ◽  
Patricia Zambrano-Robledo ◽  
...  

AlCrN/TiSi, AlCrN/TiCrSiN and AlCrN/AlCrN + CrN coatings were deposited on Inconel 718 alloy by physical vapour deposition (PVD). The corrosion behaviour of uncoated and coated specimens was evaluated using electrochemical impedance spectroscopy (EIS) at open circuit potential in a 3.5 wt.% NaCl and 2 wt.% H2SO4 solutions. The EIS data acquired were curve fitted and analysed by equivalent circuit models to calculate the pore resistance, the charge transfer resistance and the capacitance. The Nyquist diagrams of all systems showed one part of the semicircle which could relate that reaction is a one step process, except for the AlCrN/TiCrSiN and AlCrN/AlCrN + CrN coatings in H2SO4 solution, for which two semicircles related to active corrosion in substrate alloy were found. However, from the Bode plots, it was possible to identify two the time constants for all systems exposed to NaCl and H2SO4 solutions. According to electrochemical results, the corrosion resistance of the AlCrN/TiSiN coating was better in the NaCl solution, whereas the AlCrN/AlCrN + CrN coating show better performance in the Sulphuric Acid solutions.


Coatings ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 172 ◽  
Author(s):  
Damir Hamulić ◽  
Peter Rodič ◽  
Matic Poberžnik ◽  
Marjan Jereb ◽  
Janez Kovač ◽  
...  

This study investigated polysiloxane hybrid sol-gel coatings synthesized from tetraethyl orthosilicate (TEOS), 3-(trimethoxysilyl)propyl methacrylate (MAPTMS) and two different precursors, i.e., methyl- or ethyl- methacrylate (MMA or EMA), as corrosion protection of aluminium alloy 7075-T6. The hypothesis was that the additional alkyl group might affect the chemical properties and, consequently, the corrosion properties. Synthesis of the sols proceeded in two steps, each involving either MMA or EMA in the same molar ratio. The resulting sols, siloxane-(poly(methyl methacrylate-co-MAPTMS)) or siloxane-(poly(ethyl methacrylate-co-MAPTMS)), were applied on aluminium alloy followed by characterization in terms of chemical structure and composition, topography, wettability, adhesion and corrosion resistance in 0.1 M sodium chloride solution. The chemical properties of sols, monoliths and coatings were investigated using Fourier transform infrared spectrometry, solid state nuclear magnetic resonance spectrometry, X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. Coatings were similar in terms of surface topography, while the wettability of the coating with EMA showed 6° greater water contact angle compared to the coating with MMA. Both coatings were shown, by electrochemical impedance spectroscopy in 0.1 M NaCl solution, to act as barriers to protect the underlying substrate in which coating with EMA exhibits better protection properties after 2 months of immersion. Adhesion tests confirmed the highest grade of adhesion to the substrate for both coatings. Testing in a salt-spray chamber demonstrated excellent corrosion protection, where coatings remaining intact after more than 600 h of exposure.


2020 ◽  
Author(s):  
Carolina Assis do Nascimento

The aim of this study was to compare the surface micromorphology and corrosion resistance of diferent temporary anchoragedevices (TADs) composed of titanium alloy (SIN®) and stainless steel (DAT Steel® and Bio Ray®). Ten samples of eachTAD were submitted to qualitative analyses using energy-dispersive and scanning electronic microscopy before and afterimmersion in artifcial saliva (1500 ppm of fuoride) for 30 days. The chemical analysis was done by X-ray fuorescence,and the corrosion tests were performed by electrochemical means (open circuit potential—OCP, potentiostat, and electrochemical impedance spectroscopy—EIS, using anodic potentiodynamic polarization curves). Passive flm resistance (PFR)and corrosion current were established. The corrosion rate was determined by the mass loss test. Greater smoothness andfewer machining defects were observed for the stainless steel TAD before artifcial saliva immersion. Comparatively, highercorrosion resistance was found for titanium alloy TAD after immersion in saliva. There was no release of ions into the TADwhen immersed in artifcial saliva. ANOVA and Tukey tests showed that OCP (V) was signifcantly lower for the titaniumalloy TAD (p=0.030) than the stainless steel brands. Epite (V) and Epite−OCP (V) were signifcantly higher for the titaniumalloy TAD (p=0.0009 and p=0.0005, respectively). Stainless steel TADs presented lower roughness surface than titaniumalloy TAD, although the latter presented higher corrosion resistance than the former


2011 ◽  
Vol 194-196 ◽  
pp. 411-415 ◽  
Author(s):  
Guo Xing Chen ◽  
Yan Gao ◽  
Shu Hui Wu ◽  
Jin Li Hu

In this essay, the effects of grain refinement on corrosion behavior and hardness of equal-channel-angular-pressed (ECAPed) AISI 304 austenitic SS were studied. Finer grains with average size of 5μm in the specimen were obtained after four ECAPed passes compared with as-received one with grain size in range of 55μm Strain-induced grain refinement process can increase grain boundary and dislocation. Thus, the corrosion resistance of ECAPed AISI 304 austenitic SS would be improved.The refined microstructure achieves more positive open circuit potential (OCP) and lower corrosion current density in polarization corrosion tests.Through this process, austenitic stainless steel with better performance in corrosion resistance can be gained.


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