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.

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%.

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.

GALFAN

Alloy Digest ◽  
1984 ◽  
Vol 33 (4) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Rare Earth ◽  
Steel Sheet ◽  
Heat Treating ◽  
Dip Coating ◽  
Galvanized Steel ◽  
Coat Steel Sheet ◽  
Coating Alloy ◽  
Better Than

Abstract GALFAN is a zinc-5% aluminum alloy with an addition of mischmetal to introduce small amounts of the rare-earth elements lanthanum and cerium. Its composition is eutectic and it was developed to provide a hot-dip coating alloy that would be better than zinc as a protective coating for steel. GALFAN can be used to coat steel sheet, strip and wire with only minor modification of the existing equipment used to produce galvanized steel. GALFAN coatings have good performance characteristics in a variety of applications. This datasheet provides information on composition, physical properties, and hardness. It also includes information on corrosion resistance as well as heat treating and joining. Filing Code: Zn-40. Producer or source: Zinc Research Organization Inc..

scholarly journals Corrosion Resistance of Hot Dip Zn-Mg Galvanized Steel Sheet

2003 ◽  
Vol 89 (1) ◽  
pp. 174-179 ◽  
Author(s):  
Kazumi NISHIMURA ◽  
Hidetoshi SHINDO ◽  
Hiromasa NOMURA ◽  
Kenji KATOH
Keyword(s):  
Corrosion Resistance ◽  
Steel Sheet ◽  
Galvanized Steel

Underfilm corrosion of steel sheets observed by confocal 3D-XRF technique

2014 ◽  
Vol 29 (2) ◽  
pp. 151-154 ◽  
Author(s):  
Koji Akioka ◽  
Takashi Nakazawa ◽  
Takashi Doi ◽  
Masahiro Arai ◽  
Kouichi Tsuji
Keyword(s):  
Steel Sheet ◽  
Zinc Phosphate ◽  
Profile Analysis ◽  
Substrate Surface ◽  
Galvanized Steel ◽  
Nacl Solution ◽  
Phosphate Layer ◽  
Steel Sheets ◽  
Corrosion Of Steel ◽  
Elemental Maps

A confocal micro-X-ray fluorescence (XRF) method with a vacuum chamber was used for investigation of underfilm corrosion that occurs on a painted steel sheet used for automotive applications. A painted steel sheet was prepared by applying electrodeposition coating onto an electro-galvanized steel sheet with a zinc phosphate conversion coating. The spatial resolution of the confocal micro-XRF was about 10.9 ?m at an energy of 17.4 keV. The phosphorus signal from the zinc phosphate layer was able to be observed nondestructively by measuring under the vacuum condition. Each layer of the painted steel sheet was observed from the depth profile analysis of the characteristic elements of each layer. The painted steel sheet was scratched to expose the substrate surface, and then the sheet was then immersed in a NaCl solution for 10 days. The in-depth elemental map of Ti of the corroded steel sheet revealed blister-type corrosion around the scratch. The in-depth elemental maps of Zn and P suggested that the zinc phosphate layer dissolved from the scratched part into the NaCl solution.

Chromate-Free Passive Films Made by Manganate and Waterborne Polyurethane on Galvanized Steel Sheets

2010 ◽  
Vol 154-155 ◽  
pp. 292-298
Author(s):  
Xiang Hua Kong ◽  
Hui Yang ◽  
Ya Xuan Liu ◽  
Wan Heng Lu ◽  
Jing Guo ◽  
...  
Keyword(s):  
Steel Sheet ◽  
Waterborne Polyurethane ◽  
Passive Films ◽  
Galvanized Steel ◽  
Sem Observation ◽  
Steel Sheets ◽  
Environmental Friendly ◽  
Xrd Patterns ◽  
Steel Substrates

In order to develop an environmental friendly passive films on galvanized steel sheet, a chromium-free passive solution based on waterborne polyurethane (WPU) and Manganate was studied. The results show that the optimized compositions in passive solution are KMnO4 6g/L, (NH2)2CS 5g/L and WPU 150g/L. The passive films were prepared by dipping steel substrates into the passive solution for 10 seconds and drying at 120 °C for 30 seconds. SEM observation shows that the film’s thickness is about 1.5 µm. XRD patterns indicates that the chromate-free passive films mainly consisted of MnO2 and K2MnO4. Anticorrosion tests indicate that the chromate-free passive films can provide an excellent barrier to corrosive agents.

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