2. Why Metal Coated Steel?
 The basic purpose of coated steel is to prevent corrosion
and enhance the surface life of base metal. Zinc acts as a
cathodic protection and prevents the base metal from
 The coating protects the surface of the steel from oxidation
and it is also used to enhance the appearance of the
 Each of these coated steel has its own application,
depending on where they are used and to which
environment they would be exposed to.
3. Metal Coated Steel Products
 Galvanized (GI) – Hot Dipped & Electrogalvanized
 Galvalume (GL)
 Pre-Painted Steel
 Tin plate
4. Metal Coated Steel Products
 Only first 4 categories are considered in this
presentation, since they are the most widely used
coated steel products.
 Aluzinc, Pre-painted Steel and Tin plate are not
covered in this article.
5. Differences between coated Steel
Zinc on Steel
Zinc reacts with
Iron to form Zn
55%- Al ;
95% Zinc ;
5% - Al
( 1 to 5 scale)
Yes for HDGI
 Galfan is the most recent invention of the above.
 Galvalume and Galfan are registered and patented trademarks
brands and only those manufacturers with license from the
brand owners can produce and sell in these brands.
 There are different grades within each variety of above products
Strength of the Steel.
2. Coating Mass – Amount of coating
3. Surface protection (Oiling, chemical passivation, organic
4. Surface Quality
Coated steel are normally designated as follows
Grade of steel + coating + spangle designation + surface quality + surface
Just to give an example let us consider the grade,
DX53D ZF140 MBC
DX53D – Deep Drawing grade (European Standard).
ZF – Galvannealed
255 – Coating mass
M – Mini spangle
B – “B” type surface Quality
C – Chemical Passivation.
8. Some Additional Info
 American and European Standards are most commonly
used to designate the grades of coated products.
 Color coated steel (Pre-painted steel) is normally on base
material of GI, GL. They are designated as PPGI and PPGL.
Products of GI and GL when sold without color coating or
pre-painting, they are referred as “Bare” GI or “Bare GL.
Galvanised iron (PPGI) & Pre-painted
Galvalume (PPGL). PPGL is the famous of the two.