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.

    What is dual phase steel?

    The microstructures of dual phase steels are largely a ferritic matrix with martensitic “islands” as the hard second phase. The soft ferrite phase is virtually continuous, so automotive DP steels have excellent global ductility. When dual phase steels are deformed, the strain is concentrated in the lower-strength ferrite that surrounds the islands of martensite. This results in DP steels’ high initial work-hardening rate (n-value).

    Higher strength (e.g., 1000+ MPa TS) dual phase grades are most commonly achieved by increasing the amount of martensite and bainite. At a given high tensile strength, dual phase steels show a low yield ratio (Re/Rm) and a strong work hardening capacity. Dual phase steels are therefore especially suited for forming operations with high stretching portions.

    DP steel properties

    • Low yield-to-tensile strength ratio provides excellent ductility for superior cold forming with high ultimate tensile strengths.
    • High strain hardening and bake hardening further increase tensile strength.
    • Excellent deep drawing and high stretching properties.
    • Very good crash performance: high strain rate sensitivity means the faster a DP profile is crushed, the more energy it absorbs.
    • Custom yield strength levels can be engineered for specific applications.
    • High resistance to local constriction produces highly uniform elongation.
    • Good RSW weldability.
    • Uncoated or with corrosion protection using EG, GI, GA and ZA metal coatings.
    • Enables up to 20% lighter weight structural components compared to micro-alloyed steel grades.

    Automotive applications for dual phase steels

    Cold-rolled dual phase steels are widely specified for their lightweight and energy-absorbing performance in automotive structural and crash components, including car parts with complex geometries. Applications include:

    • Bumpers
    • Cross members
    • Engine cradles
    • Floor panels
    • Front sub-frame package trays
    • Longitudinal beams
    • Pillars and pillar reinforcements
    • Rails: front, rear and roof
    • Rear shock reinforcements
    • Seats
    • Shotguns
    • Side members
    • Sill (rocker) reinforcements
    • Tunnels and reinforcements

    Looking for even greater ductility for even more complex geometries? See our dual phase with high formability/ductility (DH) grades.

    Complex Phase steel for automotive applications

    Grades and mechanical properties for Docol dual phase steel

    For Dual Phase (DP) steels there is a big difference in yield and tensile strength in un-deformed areas. The work hardening in forming is very strong. DP steels have good formability compared to its strength but are limited in hole expansion. With its lean composition these steels are easy to weld but sensitive to heat treatment (>200°C).

    Hide/Show specific columns Edit
    Select columns to display
      Product Family Product name Coating Dimensions Standards Datasheet
      Docol 500DP Docol CR290Y490T DP UC, GI, GA*, ZA T: 0.50 - 3.00 mm
      W: Up to 1527 mm
      VDA 239-100

      Docol 500DP

      Docol CR230Y500T DL UC T: 0.50 - 2.10 mm
      W: Up to 1527 mm
      SSAB

      Docol 500DP

      Docol CR290Y500T DP UC T: 0.50 - 2.10 mm
      W: Up to 1527 mm
      SSAB

      Docol 500DP

      Docol 600DP Docol CR330Y590T DP UC, GI, GA, ZA T: 0.50 - 3.00 mm
      W: Up to 1527 mm
      VDA 239-100

      Docol 600DP

      Docol CR280Y600T DL UC T: 0.50 - 2.10 mm
      W: Up to 1527 mm
      SSAB

      Docol 600DP

      Docol CR350Y600T DP UC T: 0.50 - 2.10 mm
      W: Up to 1527 mm
      SSAB

      Docol 600DP

      Docol 800DP Docol CR440Y780T DP UC, GI, GA, ZA* T: 0.50 - 2.50 mm
      W: Up to 1527 mm
      VDA 239-100

      Docol 800DP

      Docol CR450Y780T DP UC T: 0.80 - 2.00 mm
      W: Up to 1527 mm
      SSAB

      Docol 800DP

      Docol CR390Y800T DL UC T: 0.50 - 2.10 mm
      W: Up to 1527 mm
      SSAB

      Docol 800DP

      Docol CR500Y800T DP UC T: 0.50 - 2.10 mm
      W: Up to 1527 mm
      SSAB

      Docol 800DP

      Docol 800DPX GI, GA* T: 0.80 - 2.00 mm
      W: Up to 1527 mm
      SSAB

      Docol 800DP

      Docol 1000DP Docol CR590Y980T DP UC, EG, GI, GA, ZA T: 0.50 - 2.10 mm
      W: Up to 1527 mm
      VDA 239-100

      Docol 1000DP

      Docol CR700Y980T DP UC, EG, GI, GA*, ZA* T: 0.70 - 2.10 mm
      W: Up to 1527 mm
      VDA 239-100

      Docol 1000DP

      Docol CR700Y980T DP LCE UC, EG, GI, GA*, ZA* T: 0.50 - 2.10 mm
      W: Up to 1511 mm
      SSAB

      Docol 1000DP

      Docol CR700Y1000T DP UC, EG T: 0.50 - 2.00 mm
      W: Up to 1527 mm
      SSAB

      Docol 1000DP

      Docol 1000DPX GI, GA* T: 1.00 - 2.00 mm
      W: Up to 1320 mm
      SSAB

      Docol 1000DP

      Compare parameters

      Select one parameter to compare

      Comparison

        *Available upon request.

        Forming Docol dual phase steels

        • Low YS-to-TS ratios means high ductility, providing excellent stampability, drawability and global formability — but with high tensile strengths.
        • Strain hardening and bake hardening can further increase tensile strength levels in the final part.
        • With less alloys than hot-rolled (HR) DP, Docol cold-rolled dual phase (CR DP) is more readily weldable, including resistance spot welding.

        Do you have forming questions about DP grades? Our Technical Support can provide specific DP steel stamping, drawing, and forming guidance for your automotive component, as well as recommending our dual phase with high formability/ductility as required.

        Forming of dual phase steel with high formability

        Additional benefits from Docol DP steels

        • Four cold-rolled, steel “strength families”: Docol 500DP, Docol 600DP, Docol 800DP and Docol 1000DP.
        • 48 standard grades within the four Docol dual phase families, targeting specific YS/TS minimums and standards specifications — with another 11 DP grades available upon request.
        • EG, GI, GA and ZA corrosion protection available on many dual phase grades.

        OEM-specific dual phase steels

        Individual Docol DP steel grades can be tailored to OEM specifications or made to internationally accepted standards, such as VDA 239-100:2016, EN 10338:2015, EN 10346:2015, or SSAB’s own high standards. We encourage you to reach out early in your design process in case your crash or structural component requires specific dual phase steel properties or is a better candidate for our dual phase with high formability/ductility (DH) grades.

        The benefits of Docol® DP steel for each team member

        Safety engineers: With their low yield-to-tensile strength ratio, dual phase steel are excellent for energy-absorbing crash components.

        Lightweighting engineers: Up to 20% lighter than micro-alloyed steels, providing numerous “down-gauging” options for thickness reduction in structural auto parts.

        Production engineers: High ductility for excellent global formability, with uniform elongation for deep-drawn parts. Good RSW weldability.

        Buyers: Huge range of Docol dual phase steel options to meet your engineers’ specific application needs, plus DH options.

        Lower your embedded CO2

        Docol dual phase is "future-proofed".

        TRIAL MATERIAL STOCK

        Try it for yourself

        With our Trial Material Stock Center, you can get AHSS samples for most of our commercially available steels – as well as samples for our newest but not yet commercially released grades. Unique to the industry, we ship coils, sheets and custom lengths of any size. In 1 to 2 weeks, your material is ready for dispatch to anywhere in the world.

        Other steel categories