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Aluminized stell is steel that has been hot-dip coated both sides with aluminum-silicon alloy. This process assures a tight metallurgical bond between the steel sheet and its aluminum coating, producing a material with a unique combination of properties possessed neither by steel nor by aluminum alone. Aluminized steel shows a better bahavior against corrosion and keeps the properties of the base material steel for temperature lower than 800' C. For example, it is commonly used for heat exchangers in residential furnaces, mufflers, ovens, ranges, water heaters, fireplaces, bar-b-que burners, and baking pans.
 
  - Very fine grains due to the suppression of the growth of aluminium crystal during solidification of aluminium melt(5 to 10% silicon contaoned)
- Uniform surface condition and excellent corrosion resistance resulting from the sacrtficing effect of aluminum
- Good apperance after painting
The heat resistance of ALCOSTA is excellent compared to that of zinc-coated steel sheet, galvannealed steel sheet, and coldrolled steel sheet, Absolutely no changes in appearance and discoloration are observed even under extended exposure to the temperature of 450˚C the coating material transforms to aluminium-iron alloy layer so that heat resistance and corrosion resistance are preserved even of discoloration occurs. The coating maintains its sacrificial proporties up to the temperature of approximately 600˚C.
The ALCOSTA is procided with excellent thermal reflectivity due to the fineness of its surface, The thermal reflectivity of ALCOSTA at 450˚C. reaches up to approximately 80%, and this is applied to thermal reflectors for toasters, gas ranges, oil stove, and so forth.
The corrosion resistance of ALCOSTA is excellent due to the coating characteristics to from a thin stable oxide layer and hydroxidation layer in the air and water, respectively.

CORROSION RESISTANCE IN ACID SOLUTION
ALCOSTA is provided with strong corrosion resistance in acidic solution compared to gatvanxed steel sheet.
SALT SPRAY TEST
Aluminium shows lowered electrochemical potential in snline water.
Fe-Al galvanic cell protects steel sheet by sacrificing Al.
The Excellent corrosion resistance of ALCOSTA steel sheet has been verified as shown in the following figure.

SALT SPRAY TEST RESULTS FOR EACH PRODUCT
CORROSION RESISTANCE TEST WITH RESPECT TO EXHAUST GAS
As a result of corrosion resistance test with respect to exhaust gas, the sorrosion resistance performance of ALCOSTA has been verified to be better than that of EGI or CR steel sheet and to be comparable to that of stainiess steels.
WEATHERABILITY
ALCOSTA is provided with excellent weatherability under severely corrosive environments as in industrial area due to its tendency to form a fine and stable oxide layer on the surface.
ALCOSTA has generally been understood being in formability dur to the presence of brittle alloy layer between the steel and aluminium layers. But, when formability of ALCOSTA is compared with that of cold-rolled steel sheets and galvanized steel sheets, DQ and DDQ grades of ALCOSTA shows better formability than those.
MATERIAL
CLASS
CODE
TENSILE TEST
HARDNE SS(HrB)
YP(kgf/mm2)
TS(kgf/mm2)
EL(%)
ALCOSTA Commercial SA1C
23
36
35
40

Drawing
SA1D
21
32
38
38
COLD-ROLLED STEEL SEET Deep-Drawing SA1E
20
31
40
35
Commercial SPCC
24
34
38
36
Paintability of aluminum coating is better than of galvanized steel sheet. In order to improve paint adhesion quality, chemical treatment is necessary. But POSCO C&C chromate solution makes the excellent paintability without further chemical treatment
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