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1. Pure Zn(Electro Galvanized Sheet)

Workability

Compared with GI and GA, this has less coating weight and has no heat influence during manufacturing process. In this light, it maintains the material characteristics and  workability of cold rolled sheet which is the base material.

Anti-Corrosion
 Sacrificial anoid reaction of Zn's galvanic action protects the base metal (Zn Zn+2+2e-, 2H,+,+2e- →H2). A thin carbonic acid zinc film is formed on the surface which acts as a buffer to corrosion when exposed to air.
Paintabilty
Smooth and even surface guarantees good paintability. In addition, phosphate treatment improves paint adhesiveness and corrosion resistance.
Weldability
 Pure Zn galvanized sheet has a wide contact area when pressure is applied and electricity conductivity is lower than cold rolled sheets thus weldability is inferior to others. However, good spot welding and seam welding are possible with appropriate welding conditions and post -treatment processes.
Strength of welded part according to the changes of welding current pressure
Properties of repeated welding(250kgf,11.4kA)

2. Zn-Fe(Electro Alloy Coated Steel Sheet)
Due to Fe in the coating, Zn-Fe electro alloy coated steel sheet has great weldability and paintability. It also has strong corrosion resistance.

3. Zn-Ni(Electro Alloy coated Steel Sheet)

Zn-Ni electro alloy coated steel sheet has been developed to safeguard automobile bodies from perforation corrosion due to NaCl and CaCl2 sprayed on the road to prevent ice formation in the winter. Thanks to Ni, this steel sheet is stronger compared with other products and has higher fusion point. Thus, compared with pure Zn steel sheet, the surface of Zn-Ni coated sheet does not soften or melt like pure Zn. It is also possible to weld at a comparably lower electric current. Paintabilty and corrosion resistance are also excellent.

Weldability Comparison : Pure Zn vs. Zn-Ni
Corrosion Resistance Comparison : Pure Zn vs. Zn-Ni

4. Terne Sheet (Pb-Sn Electro Alloy Coated Sheet)

Unlike Zn coated steel which prevents corrosion with its sacrificial anode system, Pb-Sn coated layer of Terne Sheet forms a protective film that precludes corrosion. It also has great soldering malleability. Due to good ductility, Terne Sheet has excellent workability as the coated layer acts as lubricant when deep drawing. It is used to make fuel tanks, radiators, and home appliances because it produce little or no rust and corrosion materials.
Quality Comparison by Sn content Gasoline Resistance Comparison Graph

5.Characteristics According to Post-Treatment Process

Treatment
Type
Coating Structure
Characteristics
Applications
Corrosion resistance to outdoor exposure Paintability Anti-Fingerprint Drawability Weldability Conductivity
Phosphate
PL
 1~3g/m²of phosphate is coated to enhance paintability
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 for painting
Chromate
General(CL.EL)
 5~15mg/m²of chromate is coated to improve corrosion resistance CL: SPRAY TYPE El: electrolytic chrome
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 general use
Special (CH, EM, EH)
 Chrome coating weight is increased to further enhance corrosion resistance.

CH (80~160mg/m²) EM (45~65mg/m²) EH (100˜120mg/m²) CH: SPRAY TYPE EM.EH: electrolytic chrome
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 inner panels of home appliances
lubrication
General Cr (LD)
Drawing is possible without press oil due to sprinkled lubricant resin after chromate treatment Cr:5˜15mg/m² Resin:0.6˜1.0µm
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 motor cover Cassette, VTR Deck copier panel home appliances panel
Thick Cr (LH)
Drawing is possible due to sprinkled lubricant resin after chromate treatment Cr:30˜50mg/m² Resin:0.6˜1.0µm
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Anti-Fingerprint
General Thin coating (AD)
 Thin resin layer is coated to improve conductivity compared with general thick coating type (0.5˜1.1µm)
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 general uses computer cases cassette, VTR Deck copier panel home appliances panel
Electrolytic organic general thin (OM)
 electrolytic organic anti-fingerprint treated product Compared with general thick coated type, it has excellent anti-scratch and shine after chrome treatment (46~mg/m²) thin layer of resin(800~1,200mg/m²)is applied
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 computer frame & body compact disk fod
Electrolytic organic general thin (OP)
 Organic phosphate anti-fingerprint treated product. outstanding corrosion resistance after phosphate treatment(0.5~3g/m²)thin resin layer(800~1,200mg/m²)is applied.
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Electrolytic organic general thin (NS)
 Non-Organic Chrome Anti-treated product Excellent weldability after chrome treatment40~60mg/m² thin resin layer400~700mg/m²is applied
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Cassette
VTR DECK
home appliances panel
Special Thin Coating
(AH)
(AM)
To improve corrosion resistance and conductivity after chrome treatment
AH
Cr 30~60mg/m2
AM
Cr 80~160mg/m2 thin resin layer is coated
(0.5~1.1)
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cassette
VTR DECK
home appliances panel

1. ●Excellent, ◎Good, ○Normal
2. Coating structure of anti-fingerprint treatment and lubricant coating
Organic Coating
Cr Coating
Zn
STEEL
3.AD AH LD LH : produced at Pohang Works AM OP OM NS EL EM EH : produced at kwangyang Works
4. Separate consultations are recommended for adjusting the weight of chromate coating and organic coating (anti-fingerprint treatment)
5. Paintability : prior paintability test must be performed to be used for painting (pre-treatment method, painting method, solution are different)
6. Non-organic anti-fingerprint treatment improves electric weldability

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