We will always be together with our customers.

What isPosMAC?

PosMAC(POSCO Magnesium Aluminium alloy Coating product) is a ternary alloy coated steel(Zn- 3%Mg- 2.5%Al) with high corrosion resistance developed with POSCO’s own technology. * PosMAC®is the registered trademark of POSCO.

Configuration & Characteristics
제품 구성 이미지

PPosMAC is a corrosion resistant products that is 5 to 10 times stronger resistance than that of a normal hot-dip galvanized steel sheet(GI, GI(H)) with the same coating weight. PosMAC has an excellent cross-section corrosion resistance; normal thick plating products can be replaced with this product.

The same processing, assembly and painting process can be applied to PosMAC as one would apply to GI.

Characteristics comparison

PosMAC is superior to GI in corrosion resistance on flat, machined, cross-section parts and is superior to galvalume in cross-section corrosion resistance.

Quality items PosMAC3.0 GI Galvalume
Hardness(Hv) of coating layer 110 ~ 130 60 ~ 80 80 ~ 100
Friction characteristics X
Corrosion resistance Flat sheet X
Cross-section X
Chemical resistance
Equipment specifications
설비 사진
Classification Pohang #1CGL 광양 #2CGL
Operation date 2012. 04 1992. 06
Capacity 750 thousands ton/yea 510천톤/년
Product dimensions Thickness 0.4~4.5mm 0.45~2.3mm
Width 800~1,650mm 720~1,860mm
Coating weight 60~400 g/m2 80~350 g/m2
Product grade General, Structura 자동차용, 일반용, 구조용
Post treatment Chromate(Cr6+, Cr3+), Cr-free, Oilin Chromate(Cr3+), 도유
Manufacturing equipment
  • Entry

    The equipments at the entry section are composed of two pay off reels and a welder.

  • Shot blast, Pickling
    Shot blast, Pickling

    The scales from an HR coil can be removed completely by passing through the shot blast and pickling tank.

  • Galvanizing

    Zn-Mg-Al is coated onto the surface of the steel sheet after passing the annealing furnace in the pot reserved for PosMAC, and then the targeted coating weight is achieved by spraying high pressurized air from the air knife.

  • SPM & Post treatment
    SPM & Post treatment

    In order to obtain the flat shape and elegant surface, PosMAC product get passed through a skin pass mill. Also to prevent any white rust, product surface is coated with Cr-free or chromate to improve corrosion resistance property.

  • Inspection & Coiling
    Inspection & Coiling

    The equipment at the exit section are composed of an inspection table and an oiler equipment where the products are inspected synthetically and judged whether they are adequate for sale.

Why PosMAC® has excellent corrosion resistance?

The magnesium(Mg) in PosMAC’s coating layer will accelerate the formation of a dense corrosion product called “Simonkolleite (Zn5(OH)8Cl2·H2O)” which is extremely stable. When simonkolleite is formed on the surface of the coating layer in a film-like-form, it plays a role as a corrosion inhibitor for the base metal.

  • CCT Surface Cross-section
    30 cycle
    60 cycle

In addition, the upper coating layer can be dissolved to cover the cross-section and accelerate the growth of a stable corrosion product. However red-rust can be found in the already exposed steel plate, but fortunately, the film of the corrosion products covers the cross-section and serves to prevent corrosion