General information

The RobuSal®800 air-hardening steel grade from Salzgitter Flachstahl has been developed especially for automobile manufacturing. It satisfies the customer’s requirements for lighter construction, better structural durability, and outstanding crash behavior.

The brand name RobuSal® is taken from "robinia pseudoaccia”, the Latin name for the black locust tree. The black locust features a very hard and tough wood that offers long-term strength, which conveys the steel's material characteristics.

Neither the hot- nor the cold-rolled RobuSal®800 steel is standardized. This steel is a member of the family of alloyed quenched and tempered steels. In delivery condition, air-hardening steels are soft and therefore easy to form into complex components and they have high strength as a finished component.
The components are manufactured by means of deep-drawing, hydroforming (after previous pipe welding), or other forming methods and can be heat-treated (austenitized) in the furnace in protective gas and then hardened and tempered during natural cooling in the air or protective gas. This is why these are also called "air-hardened" steels.

Customer advantages with RobuSal®800

  • Very good forming characteristics with high component strength
  • Forming on existing systems for cold and hot forming
  • Innovative alternative to high and ultra high strength steels and aluminum due to the greater strength in the hardened and tempered state
  • Superior structural durability on welded component due to air-hardened characteristics
  • Allows reduction in the plate thickness (safety and lightweight construction potential)

Form of delivery

Product Thickness in mm Width in mm Surface quality
Hot strip pickled1 2,00 - 5,002 900 - 14002 according to customer agreement
Cold strip 0,80 - 2,50 900 - 1450 Surface A acc. to DIN EN 10130

Lieferungen [EN]

Delivery is based on the provisions of DIN EN 10021, in combination with relevant valid dimensioning standards (DIN EN 10131 for cold-rolled strip, DIN EN 10051 for hot-rolled strip) or special delivery terms. The test unit comprises 20 tons, or 20 tons of each new batch, of products of the same steel grade and nominal thickness. Strip material is tested in coil form.

Dimensions of RobuSal®800 in hot-rolled state

Abmessungsgrafik RobuSal(r)800

Dimensions of RobuSal®800 in cold rolled state

Chemical composition (melt analysis in percent by weight)

Sorte C Mn Si P S Al Ti Cr B Mo V
max. max. min.
RobuSal®800 0,06 - 0,12 1,80 - 2,20 0,22 - 0,34 0.020 0.010 0,020 - 0,060 0,010 - 0,050 0,60 - 1,00 0,0015 - 0,0060 0,10 - 0,40 0,05 - 0,09

Mechanical values derived from tensile test along the welding direction

Product n-value Re Rm A80 A5
MPa MPa % %
Hot strip  - 260 - 400 460 - 650 - ≥ 25
Cold strip ≥ 0.14 290 - 420 450 - 580 ≥ 25 ≥ 14

After air-hardening (i.e. annealing with aircooling and subsequent tempering) this steel grade features a tensile strength up to 1000 MPa with a total elongation A5 ≥ 13%.

The characteristic values available after hardening are process- and component-specific and are produced at the responsibility of the user. In a soft state, with hot-dip galvanizing, the steel demonstrates a comparable increase in strength to the bake-hardening effect (increase in yield point approx. 80 MPa).

Options for use

Hot- and cold-rolled alloyed tempered steels were developed especially for automotive engineering. An increasing number of applications in other areas can be expected.
This steel features very good forming capabilities in the cold-rolled delivery state and is thus suitable for the production of components with a complex structure. It reaches its ultimate strength after heat treatment with cooling in air or protective gas. This steel was specially developed to meet the requirements of lightweight design and construction and ensure outstanding vehicle crash properties. The mechanical properties of the finished parts enable significant weight reduction.

The combination of forming and hardening capabilities makes RobuSal®800 particularly suitable for the construction of welded components subjected to high static and dynamic stresses and for loadbearing and safety-relevant components in the automotive industry.

Steel manufacture and the production of hot and cold strip takes place at Salzgitter Flachstahl GmbH. This steel strip can additionally be used for the production of HF-welded precision tubes (in future, laser-welded tubes, otherwise known as single tubes, will also be available) in accordance with EN 10305-2 or EN 10305-3 at the company‘s own subsidiaries. In this case, the customer receives flat material and tubes with identical composition virtually from a single stop. These tubes are particularly suitable for hydroforming applications where, thanks to the good forming properties of the steel, even the most complex of parts can be created without intermediate annealing.

The steel can be welded either manually or mechanically using all electrical welding techniques,
in accordance with the general technical rules. RobuSal®800 does not require the addition of any expensive, highquality filler materials.
The components made of air-hardening steels respond well to coating methods (KTL, conventional batch hot dip galvanizing, high-temperature batch hot dip galvanizing).

Example applications

Cross members, center (B) pillar, chassis elements, reinforcing tubes of A pillar, diverse structural elements, tunnel section