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Coatings and Surface Quality according VDA 239-100

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Coatings and Surface Quality according VDA 239-100

In addition to the steel base grades, the surfaces are also standardized in the recommendation of the German Association of the Automotive Industry (VDA).

The VDA 239-100 includes the following coatings.

  • Electrogalvanized Coating (EG)
  • Hot Dip Zinc Coating (GI)
  • Hot Dip Coating with Zinc-Iron Alloy (Galvannealed, GA)
  • Hot Dip Coating with Aluminum-Silicon Coating (AS)
  • Hot Dip Coating with Zinc-Magnesium Coating (ZM)

Coating and surface types according to VDA 239-100

The coating is determined by the type of coating and the coating mass in g/m² for each side. Uncoated flat products are specified by indicating “UC” (uncoated) instead of a coating type and coating weight. The usual surface type is indicated by a “U” for cold rolled, non-exposed skin parts (Unexposed). Outer panels parts are specified by an “E”. For undressed hot-rolled products without special surface finish requirements, the surface type “U” may be omitted.

Electrolytic galvanizing (EG)
Zinc coating with a zinc content of at least 99.9 % by mass electrolytically applied in a continuous coating process on a suitable prepared steel surface.

Hot-dip coating with zinc coating (hot-dip galvanizing, GI)
Zinc coating applied in a continuous process by passing the sheet steel through a molten bath with a zinc content of at least 99 % by mass.

Hot dipping refinement with zinc-iron alloy coating (Galvannealed, GA)
This zinc-iron alloy coating is generated by immersing the prepared strip in a molten bath containing a zinc content of at least 99 % and a subsequent annealing. At the same time iron diffuses into the zinc layer. The resulting zinc-iron coating has a uniform matt grey appearance and an iron content of normally 8 to 13 % by mass.

Hot dip finishing with aluminum-silicon coating (AS)
Application of an aluminum-silicon coating by passing the prepared strip through a molten bath with aluminum and a silicon content of 8 to 11 % by mass.

Hot-dip coating with zinc-magnesium coating (ZM)
Application of a zinc-magnesium coating by passing the prepared strip through a molten zinc bath alloyed with magnesium and aluminum. The alloying element contents in the coating including the Fe2Al5 barrier layer shall be 1,0 – 2,0 % by mass Magnesium and 1,0 – 3,0 % by mass Aluminum.

Examples:

…-EG29/29-E = electrogalvanized with zinc for exposed parts
…-GI40/40-U = hot dip coating with zinc for not exposed parts
…-GA50/50-E = hot dip coating with zinc-iron alloy (galvannealed) for exposed parts
…-AS45/45-U = hot dip coating with aluminum-silicon for not exposed parts
…-ZM40/40-U = hot dip coating with zinc-magnesium for not exposed parts

The next table lists the possible coating requirements according to VDA 239-100.

Characteristic overlay factorCoating Mass per Side in g/m²EN equivalent (informative)Typical value in µmDensity in g/cm³
electrolytical galvanized coating
EG12/1212-32ZE25/251,7-4,57,1
EG18/1818-382,5-5,47,1
EG29/2929-49ZE50/504,1-6,97,1
EG47/4747-61ZE75/756,6-8,67,1
EG50/5050-707,0-9,97,1
EG53/5353-737,5-10,37,1
EG60/6060-808,5-11,37,1
EG65/6565-85ZE100/1009,2-12,07,1
EG70/7070-909,9-12,77,1

Characteristic overlay factorCoating Mass per Side in g/m²EN equivalent (informative)Typical value in µmDensity in g/cm³
Zinc coating compound
GI40/4040-60Z1005,6-8,57,1
GI50/5050-707,0-9,97,1
GI60/6060-90Z1408,5-12,77,1
GI70/7070-1009,9-14,17,1
GI85/8585-11512,0-16,27,1
GI115/115115-155Z27516,2-21,87,1

Characteristic overlay factorCoating Mass per Side in g/m²EN equivalent (informative)Typical value in µmDensity in g/cm³
Mass of zinc-iron alloy
GA40/4040-60ZF1005,6-8,57,1
GA50/5050-80ZF1207,0-11,37,1

Characteristic overlay factorCoating Mass per Side in g/m²EN equivalent (informative)Typical value in µmDensity in g/cm³
Mass of aluminum-silicon alloy
AS30/3030-65AS8010-203,0
AS45/4545-85AS12015-283,0

Characteristic overlay factorCoating Mass per Side in g/m²EN equivalent (informative)Typical value in µmDensity in g/cm³
Mass of zinc-magnesium alloy
ZM30/3030-55ZM704,4-8,66,4-6,8
ZM40/4040-65ZM905,9-10,26,4-6,8
ZM50/5050-80ZM1207,4-12,56,4-6,8

Surface for non-exterior skin parts – “U”, Unexposed

Slight surface defects are allowed as long as they do not affect the workability and adhesion of subsequent coatings.

Surface for Exterior Skin Parts – “E”, Exposed

The tested side of surface type “E” must have a uniform quality finish. It may not contain defects such as microshells or zinc bubbles that lead in the subsequent process (during painting) to paint defects. The other side must at least correspond to surface type “U”. By agreement both sides can be supplied in surface type “E”.

First details can be found at the previous tables. Furthermore, you can download the complete excerpt about the VDA 239-100 in our Quality Guides (QG) with the corresponding values via the previous link.

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