Ferritic-Bainitic steel: stretch edge flangeability for cold-forming

Ferritic-Bainitic are multi-phased steels with high hole expansion ratios and good edge stretch capabilities. FB steels are suited for cold-formed and punched flanges when lightweighting automotive components such as wheels, cross members, and other structural parts.

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What is the definition of FB steels?

Hot-rolled Ferrite-Bainite (FB) is comprised of very fine sized grains of ferrite and bainite. The ferrite delivers high elongation performance and the bainite contributes to FB’s good edge stretchability. 

Their minimal hardness differences between their phases adds to FB steel’s high hole expansion (HHE) performance and stretch flangeability, both key measures of local formability. Compared to high strength low alloy (HSLA) steels with similar strength levels, ferritic-bainitic steels have increased total elongation as well as a higher strain-hardening exponent (n-value).

Steel properties

  • High local formability — good for cold-forming of edge flanges with punched holes
  • High hole expansion ratios
  • Strong fatigue performance relative to its tensile strength; good for automotive parts subject to vibration
  • Good weldability, including resistance spot welding and arc welding

Chassis applications for ferritic-bainitic steels

With a combination of good fatigue performance and formability, hot-rolled Docol FB steels can be found in many chassis applications.

  • Suspension parts, including upper and lower control arms
  • Wheels
  • Beams and cross members
  • Chassis


Ferrite bainite steel for automotive applications

Grades and mechanical properties

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    Product Family Product name Coating Dimensions Standards Datasheet
    Docol 600FB Docol HR​440Y​580T-​FB UC, GI* T: 2.00 - 4.00 mm
    W: Up to 1600 mm
    T: 0.0787 - 0.157 in
    W: Up to 62.99 in
    VDA 239-100

    Docol 600FB

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      *Available upon request.

      Forming Docol® Ferritic-Bainitic steels

      • Particular useful for auto parts with stretched flanged edges, FB is designed for cold-forming, drawing, stamping and punching.
      • Readily weldable, including resistant spot welding (RSW).
      • Good hole expansion performance, useful for folding, bending and through-hole extensions.
      Cold forming ferrite bainite steel

      More FB steel benefits

      • Good fatigue properties for parts subject to vibration.
      • Grades are available to meet OEM-specific standards and certifications.
      • Global support and availability.

      Are you looking for OEM-specific FB grades?

      Docol® FB steel grades are supplied to VDA 239-100:2016 or OEM standards. Please contact our technical support for customized ferritic-bainitic grades for your specific automotive component.

      How your team benefits from Docol FB steels

      Safety engineers: Use higher strength steel to increase performance in crash-related components.

      Lightweighting engineers: Achieve weight reductions and crack-free stretched edges with a cold-worked high strength steel.

      Production engineers: Use cold-forming operations to produce parts featuring stretched flanged edges with punched holes.

      Buyers: Leverage an economically priced AHSS steel that uses your existing cold-forming equipment and techniques.

      Sustainability officers: Right now, Docol® FB steels have the embedded-CO2 equivalence of recycled steel and, in 2026, will become available in fossil-free grades.

      Better your lifecycle assessments

      Docol® Ferrite-Bainite steel is “future proofed.”


      Ferritic-bainitic steel samples

      SSAB ships coils, sheets and custom lengths of any size, typically in 1 to 2 weeks. Get AHSS samples for both our commercially available grades, as well as our newest steels still in development.

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      What is ferrite-bainite steel?

      Ferrite-Bainite (FB) is a hot-rolled, advanced high strength steel with a microstructure of very fine sized grains of ferrite and bainite. Ferrite has high elongation properties, while bainite is known for its good edge stretchability.


      Why use ferrite-bainite steel?

      Ferrite-bainite steel can be a good choice for chassis parts needing cold-formability and good fatigue performance, such as suspension parts like upper and lower control arms. FB steels have higher elongation and n-values than HSLA at the same strength level.


      Where is ferritic-bainitic steel used?

      Hot-rolled ferrite-bainite steels deliver good fatigue performance in combination with good formability in chassis applications:

      • Chassis
      • Suspension parts, including upper and lower control arms
      • Beams and cross members 
      • Wheels

      What is the formability of ferritic-bainitic steels?

      • Designed for cold-working – forming, drawing, stamping, punching – particularly of auto parts with stretched flanged edges.
      • Good welding properties, including RSW
      • High hole expansion properties, valuable for bending, folding and through-hole extensions


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