Get the automotive offer application

for your smartphone or tablet now.

Europe product catalogue
Flat Carbon Europe website EN | FR | DE | ES

Steels coated with Alusi®, an aluminum-silicon alloy: general points


Alusi®  coating is resistant to heat, high temperature oxidation and corrosion, and offers a high level of reflectivity, making it suitable for applications in a corrosive atmosphere at high temperatures.
With its favorable properties, Alusi® can be widely used, allowing a reduction of overall operating costs when used in place of more expensive materials. Its high level of reflectivity makes it an ideal coating for thermal insulation applications.


  • Insulating heat shields
  • Engine heat shields
  • Exhaust systems
  • Fuel tanks
  • Biodiesel filters
  • Machinery casings
  • Underbody parts

Technical characteristics

Surface appearance
Alusi® has a shiny surface (high reflectivity) with coating spangles visible to the naked eye. Alusi® retains its original appearance up to 400°C with a reflectivity level of 80%.

Composed of90% aluminum and 10% silicon, Alusi® is split into one ternary layer of alloy at the steel-coating interface, ranging from 4 to 7 microns, and an overlay of binary aluminum-silicon alloy. 

Cross-section of Alusi®coating

Coating thickness
Unless otherwise specified, the standard Alusi® coating weights and corresponding thicknesses  offered are as follows (measured at 3 points):

EN Standard 10346

g/m² double-sided

µm per side

AS 60 60 10
AS 80 80 14
AS 100 100 17
AS 120 120 20
AS 150 150 25
AS 180 180 30
AS 200 200 33

However, other requirements may be considered. Please consult us.

Coating process

Alusi® is produced by continuous immersion in a bath of molten alloy made up of approximately 90% aluminum and 10% silicon.

Recommendations for use and secondary processing

Alusi® coating provides excellent corrosion protection, in hydrocarbon and outdoor environments and at high temperatures (650-800°C).
The formation of stable and impermeable corrosion products (alumina) make this a long-lasting durable coating, clearly superior to other galvanized coatings when used for recommended applications.

The presence of a hard ternary alloy layer containing iron lends Alusi® coating a hardness that reduces the Lankford r ratio when measured in a tensile test.
By controlling this ternary layer and reducing the coating weight, however, Alusi® can be used for complex deep drawn parts such as fuel filters and fuel tanks.
The use of prelube oils and of thin organic films (EasyfilmTM) improves the deep drawing properties even further.

Temperature resistance
Alusi® coating differs from other coatings by its ability to resist high temperatures (650°C and up to 800°C for steel quality ArcelorMittal 55+AS), without delamination or scaling. This property allows Alusi® to be used in exhaust systems.

Alusi® coating retains its original shiny appearance up to 400°C with a reflectivity level of 80%. This property makes Alusi® the ideal coating for use in heat protection applications such as engine heat shields and underbody parts.

Surface appearence
Alusi® is supplied with a matte finish; three types of surface finish can be provided according to customer requirements. For certain applications, a smooth shiny finish can also be produced.

Sign up to receive Automotive news alerts by email