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

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.

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).

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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

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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

Additional application ideas

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Ferrite bainite steel for automotive applications

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Grades and mechanical properties

Product Family	Product name	Coating	Dimensions	Standards	Datasheet
	Docol HR440Y580T-FB	UC	-	-	-

Product Family

Product name

Docol HR440Y580T-FB

Coating

Dimensions

Standards

Datasheet

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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.

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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.

Custom AHSS for automotive OEMs

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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.

Future-proof your life cycle assessment

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Better your lifecycle assessments

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

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TRIAL MATERIAL STOCK

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.

Request trial material

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FAQ

Other steel categories

High strength, low alloy (HSLA) steels for cost-effective automotive lightweighting

High strength, low alloy steels are a cost-effective choice for increasing strength-to-weight ratios when compared to conventional mild carbon steels. HSLA steels also have excellent bendability and weldability and can increase the strength and/or decrease the weight for a variety of body-in-white and chassis automotive components, including suspensions, beams, and subframes.

Complex phase (CP) steels for the highest hole expansion ratios

Complex phase steels have the highest — up to 100% — hole expansion ratios available from advanced high strength steels. Their high HER values provide excellent cold-forming properties for punched and stretched edges/flanges, as well as deep-drawn shapes. CP steels’ superior yield strengths are used for high crash-energy absorption, while their elevated UTS levels enable thinner walls for significant automobile weight reductions.

High edge (HE) ductility HSLA steel

High edge ductility HSLA steel with greatly improved local formability and high hole expansion ratios – ideal for challenging auto components with complex designs on sheared stretched edges.

Martensitic steel: excellent formability-to-strength ratio

Martensitic steel combines tensile strengths up to 1700 MPa with good ductility, making it highly efficient for both vehicle lightweighting and improved crash protection — especially in anti-intrusion zones.

Dual phase with high formability/ductility for crack-free cold deep drawing

Dual phase with high formability/ductility (DH) steels are TRIP-assisted, 3rd Generation automotive steels with high global and local formability and good resistance to edge cracking. DH steel have excellent energy-absorbing properties, included reserved ductility during crash impact. DH grades are ideal for complex geometries, including cold deep drawing. DH steel's FLDs and HERs are superior to DP steels, enabling scrap reduction and more streamlined stamping.

Dual phase (DP) steel: excellent ductility and energy absorption

Dual phase automotive steels have an excellent balance of ductility, high tensile strengths, easy cold formability, and very good crash energy-absorption. Its high early-stage strain hardening (n-value) makes DP steel resistant to local necking due to strain redistribution — providing highly uniform elongation. Dual phase steel’s low yield-to-tensile-strength ratio creates high global formability for deep-drawing and high-stretching capacities — all with good weldability.

Press hardening steels (PHS) for complex shapes

Press hardening steels have four major advantages: they can be formed into very complex shapes, their ultimate tensile strength ranges up to 2000 MPa (290 ksi), there is little or no springback, and, with tailored tempering, you can combine “full hard zones” and “soft zones” for multi-function crash performance within a single part.