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Steels coated with Alusi® aluminum-silicon alloy: specific applications

Applications

Exhaust systems

Alusi® coating withstands temperatures of up to 650°C and even 800°C (ArcelorMittal 55+AS steel) without scaling or delamination and exhibits excellent corrosion resistance. For these reasons it is widely used in exhaust systems.

For each major exhaust system component, there is an Alusi® grade meeting performance requirements in service.

 

Primary downpipe

Catalytic converter

Particle Filter

Catalytic converter/
muffler connection

Front muffler/
intermediate pipe

Rear muffler

Temperature

400 - 750°C

400 - 750°C

200 - 500°C

250 - 500°C

Internal: 400 -110°C
External: 50 - 300°C

Aggression

Hot gas,
salt, mud

Hot gas, salt, mud

Hot gas, salt, mud

Hot gas, salt, mud

Internal: condensates
External: atmosphere, salt, mud

Grade

ArcelorMittal 55+AS

ArcelorMittal 55+AS

ArcelorMittal 55+AS

ArcelorMittal 55+AS

Internal casing:

ArcelorMittal 53+AS
External casing:

ArcelorMittal 54+AS
Pipe:

ArcelorMittal 51+AS - ArcelorMittal 52+AS


In the exhaust system application, a coating weight of 150 g/m² and the use of EasyfilmTM can further increase corrosion resistance.

The ArcelorMittal 55+AS grade, specifically developed to guarantee coating integrity up to 800°C and to resist high-temperature oxidation, is recommended for parts upstream of the front muffler.

Corrosion resistance comparison:

Galvanised/galfan/Alusi® in salt spray

High temperature cyclic oxidation comparison

Secondary processing - Welding
Most welding techniques (spot, seam, high frequency) and the MIG, MAG and TIG processes can be applied on Alusi® without special equipment.

Heat shields

As a result of its very good reflectivity and resistance to high temperature and corrosion, the Alusi® coating is suitable for use in the following applications:

  • Engine heat shields,
  • Underbody heat shields.

The mechanical properties of the Alusi® coating under ambient and high temperatures allow for the use of very thin coating layers, thus reducing material costs as compared to alternative rival solutions.

Reflectivity - Thermal insulation
Alusi®  coating offers excellent thermal insulation properties due to its high level of reflectivity.
Its aluminized surface reflects about 80% of the radiation emitted by a heat source between 200 and 600°C.

Alusi® ArcelorMittal 54+AS

Stiffness - Resistance to high temperature - Creep resistance

At ambient temperature, Alusi® sheet exhibits substantially higher stiffness than other solutions.

At high temperature, Alusi® retains excellent mechanical properties, lending it good creep resistance.

This makes it suitable for use in the following environments:

  • Engines, manifolds and catalytic converters,
  • Underbodies with very low clearance

Creep resistance:
Comparison Steel/Other indicative solution

Mass savings: low gauge dimensions, down to 0.25 mm

Alusi® sheet can be provided in low gauge dimensions, resulting in lighter heat shields.

ArcelorMittal can produce Alusi® sheet in 0.25 mm thickness, allowing the design of heat shields with a weight reduction of 50% compared to a conventional solution with a thickness of 0.5 mm.

Stiffness and improved drawability: the embossed aluminized steel solution

To reduce gauge dimensions while maintaining sufficient component stiffness, ArcelorMittal offers embossed Alusi® sheet.

Embossing facilitates secondary processing by simplifying the range of equipment and reducing the number of drawing operations required to produce the component.

Embossing also improves the vibratory behavior and increases the stiffness of the component.

Embossed aluminized steels with a thickness of 0.25 mm are particularly competitive compared to alternative materials.

The combination of improved drawability and stiffness makes it possible to design heat shields in Alusi® 0.25 mm, generating significant reductions in material costs compared to other materials

Embossed Alusi® heat shield in ArcelorMittal 54+AS 120

(thickness: 0.4 mm) 



Embossed Alusi®  heat shield in ArcelorMittal 54+AS 120

(thickness: 0.25 mm)

 

Alusi® heat shield in ArcelorMittal 54+AS 120

(thickness: 2 x 0.3 mm) 

 

Alusi® catalytic converter heat shield in ArcelorMittal 55+AS 120

(thickness: 0.5 mm) 


Fuel tanks and filters

The excellent resistance of Alusi® steel to the corrosion caused by gasoline, diesel and biodiesel fuels and its external corrosion resistance and deep-drawability recommend it for use in metal fuel tanks and fuel filters.

The ArcelorMittal 56+AS grade-55 g/m² double-sided, for example-is ideal for this type of application. Alusi® steels fully meet fuel permeation standards and recycling and biodiesel compatibility requirements.

Fuel tank shell

Corrosion resistance
The corrosion resistance of Alusi®coating has been demonstrated in a variety of fuel and atmospheric corrosion tests. The results show that the aluminized steel solution offers a metal fuel tank service life of 15 years.

Welding
Most welding techniques can be used to join shells (seam, Soudronic®) and other parts (MIG, MAG, braze-welding, etc.).

Deep drawing / Fuel filter

To cater to the demand in diesel filters made of Alusi® steel, ArcelorMittal has developed the ArcelorMittal 56+AS grade with low coating weight and a final surface treatment (EasyfilmTM), which preserves coating integrity and adhesion.

This combination is compatible with biodiesel.

Fuel filter

Available grades

ArcelorMittal quality

Use

YS
(MPa)

UTS
(MPa)

ef (%)
Lo = 80 mm

r
(90°)

n
(90°)

ArcelorMittal 51+AS

Roll forming - Lock seaming

 

270 - 500

≥ 22

 

 

ArcelorMittal 52+AS

Average drawing

140 - 300

270 - 420

≥ 26

 

 

ArcelorMittal 53+AS

Difficult drawing

140 - 260

270 - 380

≥ 30

 

 

ArcelorMittal 54+AS

Difficult drawing

120 - 220

260 - 350

≥ 34

1.4

0.18

ArcelorMittal 55+AS

Very difficult drawing

600°< T < 800°C

140 - 240

270 - 370

≥ 30

 

 

ArcelorMittal 56+AS

Extra-deep drawing

120 - 180

260 - 350

≥ 39

1.7

0.20

ArcelorMittal 57+AS
Thickness > 0.7 and < 1.5 mm

Extra-deep drawing

120 - 170

260 - 350

≥ 41

1.9

0.21


Mechanical properties for thickness > 0.7 mm.

(Mechanical properties for thickness < 0.7 mm: provided on consultation.)

 

Alusi® is also available in several strength grades. Please consult us for further details.

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