The Influence of Major Defects on the Properties of Continuous Galvanized Steel Sheet

2012 ◽  
Vol 445 ◽  
pp. 661-666 ◽  
Author(s):  
A. Azimi ◽  
F. Shahriari ◽  
F. Ashrafizadeh ◽  
M.R. Toroghinezhad ◽  
J. Jamshidi
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
Tensile Test ◽  
Steel Sheet ◽  
Corrosion Behaviour ◽  
Salt Spray ◽  
Galvanized Steel ◽  
Tafel Polarization ◽  
Steel Sheets ◽  
Bare Spot

Production of defect-free galvanized steel sheet is considered a major concern for automotive and other critical applications; nevertheless, the occurrence of some defects in the coated sheets is unavoidable. In order to alleviate the problem, we need to know the extent to which the properties of a galvanized sheet are influenced by the presence of a given defect. In this investigation, specimens including any of the two major defects of continuously galvanized steel sheets were selected from a large number of coated samples. The defects, including furnace roll pimples and bare spots, were microstructurally characterized and their influence on corrosion behaviour and mechanical properties of the steel sheet was evaluated. Corrosion resistance was examined via standard salt spray test and Tafel polarization. Tensile test was employed as a measure of mechanical properties of the defective galvanized sheets. The results indicated that the presence of defects had little influence on the tensile properties of the samples, but considerably reduced their corrosion resistance. Based on the results of salt spray tests, pimples reduced corrosion resistance of galvanized sheets 23 % (50 hours) on average and bare spot defects caused reduction in corrosion resistance up to 39%.

scholarly journals The relationship between surface treatments and corrosion resistance of hot-dip galvanized steel

2014 ◽  
Vol 20 (3) ◽  
pp. 165-170 ◽  
Author(s):  
Amirreza Bakhtiari
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behaviour ◽  
Salt Spray ◽  
Surface Treatments ◽  
Galvanized Steel ◽  
Tafel Polarization ◽  
Galvanized Coatings ◽  
The Relationship ◽  
Scanning Electron ◽  
Resistance Difference

In this work three surface treatments such as: polishing, sand-blast and polishedoxidized have been carried out on the hot-dip galvanized coatings. The roughness and corrosion resistance of coatings have been studied. Surface morphology of coatings has evaluated by scanning electron microscope (SEM). Corrosion behavior was analyzed by salt spray cabinet test and Tafel extrapolation test. The results showed that the sample under sand-blasted treatment exhibited the highest roughness number. Tafel polarization and salt spray cabinet tests reveal the sample with great roughness number have weak corrosion resistance. Difference observed in corrosion behaviour can be explained by difference in surface roughness.

scholarly journals Effect of Inorganic Filler Addition on Non-Combustible and Mechanical Properties of Color Coated Steel Sheets

2020 ◽  
Vol 58 (11) ◽  
pp. 768-775
Author(s):  
Moon-Hi Hong ◽  
In-kyu Kim ◽  
Hye-Jeong Yun
Keyword(s):  
Mechanical Properties ◽  
Large Scale ◽  
Salt Spray ◽  
Galvanized Steel ◽  
Inorganic Filler ◽  
Coated Steel ◽  
Coating Materials ◽  
Steel Sheets ◽  
Glow Discharge Spectroscopy ◽  
Coated Layer

Recent large-scale fires in buildings and logistic warehouses have become a major social issue, involving both property loss and multiple casualties. To make color coated steel sheets non-combustible and/or have anti-fire properties, various ways of optimizing manufacturing parameters have been investigated for outer, inner, roof and ceiling panels. In the present study, the effect of inorganic filler content and size on the non-combustible and mechanical properties of color coated steel sheets has been investigated using samples prepared as pre-painted coating materials. Both salt spray corrosion and chemical resistance tests were also carried out. Filler distribution and size were measured by optical microscopy, scanning electron microscopy and glow discharge spectroscopy, and found to be critical factors affecting non-combustible performance. As the amount of added filler increased, the non-combustible property of the color coated steel sheets improved, while mechanical properties, corrosion resistance by salt spray and chemical resistances deteriorated. During 3t-bending tests, the adhesive strength at the interface between coated layer and hot dip galvanized steel sheets was rather strong, although the filler-added upper coated layer was mostly peeled off. The mechanical properties of 30% filler addition samples were compared to samples with less than 20% filler addition. The main reason for the poorer performance was clarified in terms of filler size and crack propagation in the 3t-bended color coated layer.

Study of Corrosion Behaviour of Molybdenum Series Coatings on Galvanized Steel

2011 ◽  
Vol 399-401 ◽  
pp. 1972-1975 ◽  
Author(s):  
Hui Min Zhang ◽  
Lin Wu ◽  
Zhao Hui Ouyang ◽  
De Lian Yi ◽  
Qiao Hua ◽  
...  
Keyword(s):  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Salt Spray ◽  
Acrylic Resin ◽  
Galvanized Steel ◽  
Coupling Agents ◽  
Neutral Salt ◽  
Tafel Polarization ◽  
Chromate Coating

In this paper, an organic/inorganic molybdenum series Cr-free coating was formed on galvanized steel by simple immersion and its corrosion behavior was compared to that of a typical chromate coating. Molybdate and 1-Hydroxy-ethylidene-1, 1-diphosphonic acid (HEDP) were used as corrosion inhibitor, as well as acrylic resin and silane were used as film-former and coupling agents, respectively. The corrosion behavior of the coatings was evaluated by Neutral salt spray (NSS), Electrochemical impedance spectroscopy (EIS) and Tafel polarization. The surface topography of the samples was observed by Scanning Electron Microscopy (SEM). The results indicated that the corroded area of the Mo-HEDP treatment was only corroded 2% after 72 h spraying, while the corrosion behaviour of Mo-HEDP was closed to that of Cr pretreatment due to the synergistic reaction of molybdate and HEDP. Compared with the film of Cr treatment, Mo-HEDP passivating coating was more environmentally friendly.

Synergistic Corrosion Resistance of Cerium Film and Silane Film on Hot-Dip Galvanized Steel

2010 ◽  
Vol 34-35 ◽  
pp. 2021-2025
Author(s):  
Hai Jiang Wu ◽  
Fei Ying Yang
Keyword(s):  
Corrosion Resistance ◽  
Double Layer ◽  
Salt Spray ◽  
Galvanized Steel ◽  
Protection Efficiency ◽  
Protection Effect ◽  
Steel Sheets ◽  
Environmental Friendly ◽  
Zinc Corrosion ◽  
Silane Solution

This work aims at developing a new environmental-friendly treatment for hot-dip galvanized (HDG) steel as alternative to the classic systems based on chromates. A double layer film on the HDG steel sheets was prepared by immersing the sheets in 5 g/L Ce(NO3)3 aqueous solution and 5 vol.% silane solution in turn. The morphology of the cerium conversion film was analyzed using scanning electron microscopy (SEM). The corrosion resistance of the films was investigated by linear polarization (LPR) and natural salt spray (NSS) tests. The results show that the surface morphology of cerium conversion film appears on a “dry-mud” structure, which is favorable to enhance the combined strength between the cerium conversion and the silane film. The corrosion protection efficiency of the double layer films increases greatly, especially both the anodic and cathodic processes of zinc corrosion on the samples are suppressed conspicuously, and the synergistic protection effect of the single cerium film and the single silane film is evident.

Research of Organic/Inorganic Chromium-Free Co-Passivation Treatments for Galvanized Steel

2013 ◽  
Vol 785-786 ◽  
pp. 881-886
Author(s):  
Qi Pan ◽  
Lin Wu ◽  
De Lian Yi ◽  
Zhao Hui ◽  
Ou Yang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Composite Film ◽  
Salt Spray ◽  
Galvanized Steel ◽  
Neutral Salt ◽  
Ac Impedance Spectroscopy ◽  
Good Adhesion ◽  
Passivation Film ◽  
Tafel Polarization ◽  
Inorganic And Organic

The corrosion resistance of chromium-free passivation film with single chromate-free passivation solution to deal with galvanized steel still has a gap compared to chromate passivation. In this experiment, the passivation solution consisting of the inorganic salt as corrosion inhibitor, silane as sealer, water-based epoxy resin and additives which formed a layer of inorganic and organic composite passivation film on galvanized steel through the synergistic effect between inorganic and organic. The morphology and elements of the passivation film was analyzed by scanning electron microscopy (SEM) and the corrosion resistance of the composite film was tested by neutral salt spray test (NSS), lead acetate spot test (ASS), tafel polarization curves and AC impedance spectroscopy (EIS). The results show that the composite film has a good adhesion and an excellent corrosion resistance, the corrosion area is only 3% after 72h NSS.

Distribution of Zn and Interfacial Microstructure of Braze-Welding CMT Joints between Aluminium and Galvanized Steel Sheets

2007 ◽  
Vol 127 ◽  
pp. 43-48 ◽  
Author(s):  
J.C. Feng ◽  
Peng He ◽  
Heinz Hackl
Keyword(s):  
Solid Solution ◽  
Corrosion Resistance ◽  
Heat Affected Zone ◽  
Steel Sheet ◽  
Decisive Role ◽  
Interfacial Microstructure ◽  
The Other ◽  
Galvanized Steel ◽  
Dendritic Crystal ◽  
Steel Sheets

Distribution of Zn and interfacial microstructure of braze-welding CMT joints between aluminium and galvanized steel sheets were researched. The results showed, except the gas porosity contains a little Zn, the other areas of fusion zone almost have no Zn. Temperature plays a decisive role in the distribution of Zn. The content of Zn is higher in the dendritic crystal than the intergranular part. The Zn coat adjacent to the joint is almost evaporated entirely. The Zn coat of steel sheet in the heat-affected zone around the joint is badly destroyed, and the corrosion resistance of the joint will decline. There are FeAl3 intermetallics and Al-Fe-Zn triphase solid solution formed at the interface.

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.

The Effect of Composition and Microstructure on Corrosion Behavior in SST of Zn-Al-Mg Galvanized Steel Sheet

2013 ◽  
Vol 442 ◽  
pp. 64-69
Author(s):  
Feng Li ◽  
Jia Shun Lv ◽  
Hong Gang Yang ◽  
Fang Zhou ◽  
Leng Zhang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Steel Sheet ◽  
Alloy Composition ◽  
Element Distribution ◽  
Galvanized Steel ◽  
Good Corrosion Resistance ◽  
Excellent Corrosion Resistance

Z11A3M, Z6A3M, Z1.6A1.6M, Z1A1M and Z1M coating samples were prepared in HDPS by traditional continuous hot dipping method. The microstructure, element distribution and phase was analyzed by SEM, EPMA and XRD. The corrosion resistance was checked in SST. The result was, MgZn2 and eutectic could be found in all ZAM coating. The ZAM coatings showed excellent corrosion resistance in SST than GI. The corrosion resistance was 4.1 to 11 times of GI. There was no strong relativity between alloy composition and corrosion resistance due to Mg enrichment on the surface of coating. Edge-unsealed ZAM samples showed good corrosion resistance than edge-sealed sample.

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