The Phenomenon of Pitting Corrosion Attack on the Milled Aluminium Alloy Al 2618 Plate during Surface Preparation through Sulphuric Acid Anodising

2014 ◽  
Vol 896 ◽  
pp. 596-599
Author(s):  
Handoko Subawi ◽  
Sutarno
Keyword(s):  
Aluminium Alloy ◽  
Sulphuric Acid ◽  
Pitting Corrosion ◽  
Salt Spray ◽  
Surface Preparation ◽  
Operation Condition ◽  
Aluminium Sheet ◽  
Surface Corrosion ◽  
Corrosion Propagation ◽  
Anodised Aluminium

This study purposed to investigate corrosion characteristic on aluminium alloy by considering parameters that involved metal preparation, different surface treatment, and alloy types. Through series of the salt spray test, the rolled aluminium sheet revealed higher resistance to surface corrosion rather than milled aluminium plate. However trace elements, as reinforced filler in the metal alloy, may contribute to possible pitting corrosion. By employing sulphuric acid anodising, it revealed higher probability of pitting corrosion to attack the milled aluminium plate surface compared to rolled aluminium sheet. The surface pitting corrosion on the anodised aluminium alloy Al 2618 plate was observed through enlargement of pitting diameter and additional new pitting holes during 500 hours corrosion test. The corrosion propagation grew sharply during 500 hours test and it increased slowly after 750 hours. This study did not evaluate further variables either alloy composition, metal processing, or operation condition in anodising process.

scholarly journals Mechanical clinching and self-pierce riveting for sheet combination of 780-MPa high-strength steel and aluminium alloy A5052 sheets and durability on salt spray test of joints

2021 ◽  
Vol 113 (1-2) ◽  
pp. 59-72
Author(s):  
Yohei Abe ◽  
Ken-ichiro Mori
Keyword(s):  
Aluminium Alloy ◽  
High Strength Steel ◽  
Salt Spray ◽  
High Strength ◽  
Alloy Sheet ◽  
Galvanized Steel ◽  
Load Reduction ◽  
Minimum Thickness ◽  
Steel Sheets ◽  
Mechanical Clinching

AbstractTo increase the usage of high-strength steel and aluminium alloy sheets for lightweight automobile body panels, the joinability of sheet combinations including a 780-MPa high-strength steel and an aluminium alloy A5052 sheets by mechanical clinching and self-pierce riveting was investigated for different tool shapes in an experiment. All the sheet combinations except for the two steel sheets by self-pierce riveting, i.e., the two steel sheets, the two aluminium alloy sheets, and the steel-aluminium alloy sheets, were successfully joined by both the joining methods without the gaps among the rivet and the sheets. Then, to show the durability of the joined sheets, the corrosion behaviour and the joint strength of the aged sheets by a salt spray test were measured. The corrosion and the load reduction of the clinched and the riveted two aluminium alloy sheets were little. The corrosion of the clinched two steel sheets without the galvanized layer progressed, and then the load after 1176 h decreased by 85%. In the clinched two galvanized steel sheets, the corrosion progress slowed down by 24%. In the clinched steel and aluminium alloy sheets, the thickness reduction occurred near the minimum thickness of the upper sheet and in the upper surface on the edge of the lower aluminium alloy sheet, whereas the top surface of the upper sheet and the upper surface of the lower sheet were mainly corroded in the riveted joint. The load reduction was caused by the two thickness reductions, i.e., the reduction in the minimum thickness of the upper sheet and the reduction in the flange of the aluminium alloy sheet. Although the load of the clinched steel without the galvanized coating layer and aluminium alloy sheets decreased by about 20%, the use of the galvanized steel sheet brought the decrease by about 11%. It was found that the use of the galvanized steel sheets is effective for the decrease of strength reduction due to corrosion.

scholarly journals The Influence of Surface Preparation of the Steel during the Renovation of the Car Body on Its Corrosion Resistance

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 384
Author(s):  
Dariusz Ulbrich ◽  
Jakub Kowalczyk ◽  
Arkadiusz Stachowiak ◽  
Wojciech Sawczuk ◽  
Jaroslaw Selech
Keyword(s):  
Corrosion Resistance ◽  
Glass Bead ◽  
Salt Spray ◽  
Zinc Coating ◽  
Surface Preparation ◽  
The Other ◽  
Average Thickness ◽  
Spray Chamber ◽  
Car Body ◽  
Abrasive Blasting

The article presents the influence of the applied method used for removing the varnish coat on the corrosion resistance of the car body sheet. The tests were carried out on samples prepared from factory-painted car body elements with pearlescent, metallized and acrylic varnish. Removal of the varnish coat was performed by sandpaper grinding, glass bead blasting, disc blaze rapid stripping, soda blasting and abrasive blasting with plastic granules. The average thickness of the factory-painted coating depending on the type of lacquer ranged from about 99 to 140 µm. On the other hand, after removing the varnish, the thickness of the protective zinc coating ranged from 2 to 12.7 µm. The highest values of the zinc coating were obtained for samples in which the varnish was removed by the method such as soda blasting and abrasive blasting with plastic granules. For these two methods of surface preparation, the damage to the zinc layer protecting the steel against corrosion is the smallest and the percentage of zinc in the surface layer ranges from 58% to 78%. The final stage of the research was to test the samples after removing the varnish coat in a two-hour exposure to the corrosive environment in a salt spray chamber. Samples with the surface prepared by grinding with sandpaper reached the level of surface rusting Ri 5, while in the case of soda blasting and the use of plastic granules, no corrosion centers were observed on the surface of the car body sheet.

Study on Anodizing Processes for Formation of Nano Porous Aluminum Oxide Thin Films

2011 ◽  
Vol 236-238 ◽  
pp. 3061-3064
Author(s):  
Thein Thein Kyaw ◽  
Kyaw Myo Naing ◽  
Nyunt Win
Keyword(s):  
Oxide Film ◽  
Aluminum Oxide ◽  
Sulphuric Acid ◽  
Anodic Oxide ◽  
Film Coating ◽  
Anodic Oxide Film ◽  
Oxide Thin Film ◽  
Operation Condition ◽  
Porous Aluminum ◽  
Coating Weight

In this paper aluminum oxide thin film was prepared by anodic oxidation in various acid baths such as sulphuric acid, chromic acid and phosphoric acid with different concentrations. The thickness and appearance of the anodized films formed has been compared. The thicknesses of anodic oxide film, coating weight per unit area and coating ratio of anodic oxide film variation were determined with respect to the different electrolyte concentrations by using the thickness determination formula. Sulphuric acid gives the highest thickness aluminum oxide films, in the operation condition of 15% H2SO4solution composition, 15V, 30±2°C, 100 mA, 60 mins.

Inspection and mitigation for pitting corrosion on stainless steel process piping to prevent process safety event and loss production opportunity in Medco E&P

2021 ◽  
Author(s):  
I. Rosyadi
Keyword(s):  
Stainless Steel ◽  
Pitting Corrosion ◽  
Sun Exposure ◽  
Passive Layer ◽  
Process Safety ◽  
Pipe Surface ◽  
Corrosion Propagation ◽  
Process Piping ◽  
Safety Event ◽  
Steel Piping

Stainless steel piping has excellent corrosion resistant properties, both internal or external piping surface. In humid circumstances, sea vapor containing chlorine will be trapped on the pipe surface, especially pipes below deck with minimum sun exposure (more humid). Chlorine on the external pipe surface will damage the passive layer of stainless steel pipe. Damage speed is faster than recovery of passive layer stainless steel. This condition lead to a lot of localized pitting corrosion spread. The corrosion was detected visually and carried out with dye penetrant inspection to assure pitting condition. Actual dimension of pitting (depth, diameter) cannot be measured due to limitation of the NDE technique. This pitting corrosion can result hydrocarbon leakage as a process safety event that contributes loss of production opportunity. Without modification circumstances, this condition can be stopped immediately by application of a viscos elastic coating to prevent pitting corrosion propagation. Application of viscos elastic coating is simpler and faster when compared to conventional coating. Viscos elastic coating will protect stainless steel piping surface against oxygen and chloride in humid circumstances so that stainless steel can recover passive layer and stop pitting corrosion.

Analysis of Corrosion Behavior on External Surface of 110S Tubing

2020 ◽  
Vol 993 ◽  
pp. 1242-1250
Author(s):  
Yan Han ◽  
Cheng Zheng Li ◽  
Hua Li Zhang ◽  
Yu Fei Li ◽  
Da Jiang Zhu
Keyword(s):  
Pitting Corrosion ◽  
Corrosion Test ◽  
External Surface ◽  
Sample Surface ◽  
Outer Wall ◽  
High Concentration ◽  
Surface Corrosion ◽  
Slowing Down ◽  
Threaded Connection ◽  
Acid Test

The failure analysis of 110S tubing during acidizing process was addressed. Results showed that serious pitting corrosion occurred on the outer wall of tubing, and there was no obvious pitting on the inner wall. The maximum pitting depth on the outer wall was 1019 μm. According to the results of simulation corrosion test, needle-shaped pitting appeared on the sample surface in the test without inhibitor, the maximum depth of pitting was 158 μm; and no pitting was found on the sample surface in the test within 1.5% TG501 inhibitor; the original pitting were deepened after spent acid test, and the sample with no pitting at the beginning also showed deep pitting corrosion after 96 hours spent acid test. It was indicated that the spent acid accelerated the development of pitting significantly. The external surface corrosion of the 110S tubing was caused by the chemical reaction between the high-concentration acidifying liquid and the outer wall of the tubing. There is a gap between the tubing and coupling threaded connection, which caused the acid solution entered into the thread position, and hence the severe corrosion of the thread and pin end of the tubing happened, the joint strength was continuously reduced with corrosion development till the tripping of the coupling, and then the lower string dropped. Some suggestions were proposed for avoiding or slowing down this kind of failure based on this study.

Effect of severe plastic deformation by ECAP on corrosion behaviour of aluminium alloy AA 7075

2016 ◽  
Vol 81 (2) ◽  
pp. 55-61 ◽  
Author(s):  
M. Ilieva ◽  
R. Radev
Keyword(s):  
Corrosion Resistance ◽  
Aluminium Alloy ◽  
Equal Channel Angular Pressing ◽  
Pitting Corrosion ◽  
Corrosion Behaviour ◽  
Chloride Concentration ◽  
Chloride Ions ◽  
Angular Pressing ◽  
Pitting Corrosion Resistance ◽  
Aa 7075

Purpose: The present study compares the corrosion behaviour of overaged AA 7075 before and after equal channel angular pressing ECAP in two media, containing chlorides, in order to answer the question how grain refinement of aluminium alloys influences their corrosion properties.Design/methodology/approach: The effect of equal channel angular pressing ECAP on corrosion behaviour of aluminium alloy AA 7075 was studied in two water solutions, containing chloride ions: 1) 0.01 M Na2SO4 with addition of 0.01%Cl-, and 2) 3g/l H2O2 and 57g/l NaCl. The changes in electrochemical characteristics, provoked by grain size refinement after equal channel angular pressing ECAP, were found using potentiodynamic polarisation. Steady state potential, corrosion potential, corrosion current density; breakdown (pitting) potential of overaged and deformed by equal channel angular pressing ECAP aluminium alloy AA 7075 were measured.Findings: In the environment with lower chloride concentration equal channel angular pressing ECAP process led to increase in pitting corrosion resistance and in the medium with higher chloride concentration - to decrease in pitting corrosion resistance. That way grain refinement does not demonstrate a uni-directional influence on corrosion resistance of AA 70775.Research limitations/implications: The results suggest the possibility for development of materials having the same chemical composition but with different corrosion resistance to different environments.Originality/value: The paper presents the corrosion behaviour of ultrafine-grained aluminium alloy AA 7075 and the influence of the chloride ions concentration in the corrosion medium on this behaviour.

The effects of cold work on the incipient pitting morphology evolution of 304L stainless steels

CORROSION ◽  
10.5006/3576 ◽  
2021 ◽  
Author(s):  
Hsiao-Ming Tung ◽  
Tai-Cheng Chen ◽  
Joe-Ming Chang
Keyword(s):  
Pitting Corrosion ◽  
Stainless Steels ◽  
Laser Scanning ◽  
Electron Backscatter Diffraction ◽  
Cold Work ◽  
Salt Spray ◽  
Confocal Laser Scanning Microscope ◽  
Confocal Laser ◽  
Spray System ◽  
Cold Worked

The purpose of this study was to investigate the effects of cold work on the incipient pitting corrosion of 304L stainless steels (304L SS). The as-received (0%-CW) and 20% cold-worked (20%-CW) 304L specimens were corrosion-tested in a salt spray system with a solution of 3.5% simulated seawater for the exposure time ranging from 12, 24, 48, 96 to 192 hrs to characterize the pitting corrosion behavior of 304L SS. Weight gain and microstructures were measured using a microbalance and electron backscatter diffraction (EBSD), respectively. The dimensions of corrosion pits, depth, length and width, were analyzed by Confocal Laser Scanning Microscope (CLSM) to elucidate the pit growth process. The analysis of the rust and pit features revealed that the degree of corrosion is more severe in the 0%-CW specimen than in the 20%-CW specimen.

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