Fortiform® is the name of ArcelorMittal’s new range of AHSS steels for cold stamped automotive parts. The high strength and excellent formability of these steels offer improved safety and the potential for significant weight savings of between 10 and 20% compared to conventional AHSS solutions.
Because of their superior properties, Fortiform® steels are able to absorb more crash energy with less steel. This makes Fortiform® suitable for use in many of the structural parts of a vehicle which may be affected during an impact including front and rear members, B-pillars and windscreen pillars.
The Fortiform® range currently includes three steel grades:
The grade number indicates the tensile strength of each steel (in MPa) in the range. All are available with an electro-galvanised (ZE) or bare surface.
ArcelorMittal’s Fortiform® grades for cold stamping complement our hot stamping steel grades such as Usibor® and Ductibor®.
Fortiform® 1050 is the first steel in the new range to be made available to carmakers. The grade has already undergone formability and weldability tests with leading global vehicle manufacturers. All have approved its use and the first serially produced cars to use the new grade will roll-off production lines in 2017.
Fortiform® 980 and Fortiform® 1180 will be released for testing by automakers, followed by industrial production. Other products in the range will be developed in line with available technology and customer demand.
Production of Fortiform® involves a number of highly controlled steps. After melting and casting, the steel is hot and cold rolled to achieve the desired dimensions. The rolling stage also controls some of the steel’s final properties.
The Fortiform® steel is then continuously annealed to obtain the final microstructure and properties of the grade. If an anti-corrosion zinc coating is required, Fortiform® can be electro-galvanised prior to delivery. An additional treatment may be carried out to remove hydrogen from the steel matrix. This eliminates the risk of delayed fracture when the steel is utilised by our customers.
ArcelorMittal’s range of AHSS for carmakers includes Fortiform® for cold stamping applications, and hot stamping grades such as Usibor® and Ductibor®. This gives vehicle designers the freedom to create the safe and affordable vehicles their customers want.
Carmakers do not need to make significant changes to their production lines in order to accommodate the new Fortiform® range of steels. Some minor modifications to welding parameters may be required. As less steel is required to achieve the same strength, switching to ArcelorMittal’s Fortiform® grades can be near to cost neutral.
Steel remains the most cost-effective and most environmentally friendly material for automotive applications. Thanks to steel’s 100% recyclability and the lightweighting potential of AHSS steels, vehicles made with steel are also gentle on the environment.