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.
Complex phase steels have a bainite-ferrite microstructure with small amounts of martensite and retained austenite and pearlite. The thermal cycles used to produce CP retards recrystallization while promoting different carbo-nitride precipitations, resulting in extreme grain refinements for excellent ductility, even for high (e.g., 1200 MPa or 174 ksi) tensile strength grades.
The carbo-nitride precipitations also increase complex phase steel’s ferrite strength; as a result, CP steels have higher yield strengths than dual phase (DP) steels at equivalent tensile strength levels. Complex phase steels’ high yield strengths are used by body-in-white designers for high crash-energy absorption for safety components, such as in frame rails, reinforcements, beams, and more.
To stretch or form cut edges that are crack-free can be a major challenge when working with advanced-high strength steels. To reduce the risk of cracked (raised) edges, SSAB is introducing two new versions of hot-rolled 800 megapascal steels with extremely high edge ductility.
Many of these steel properties should contradict one another: formability vs. high strength, high edge ductility vs. good crash performance. But these steels deliver all of these properties – and, especially, they deliver very high edge ductility.
These new high edge ductility AHSSs can step in as "problem-solvers". Or, they can be used on auto parts where you want higher confidence that you won't have cracked edges.
HER in the product name means we’ve tested every shipment to guarantee a minimum hole expansion ratio and for Docol HR800HER-75 we guarantee 45% HER with a typical value of 75%.
This steel grade is tested to guarantee an extremely high edge ductility of 65% HER – with a typical HER value of 100%, which is among the highest on the market for 800 megapascal automotive steels.
Hot-rolled Docol CP steels deliver good fatigue resistance and can be suitable for car parts subjected to dynamic alternating stress. For example, multilink suspensions, trailing arms, torsion beams and subframes.
Cold-rolled Docol CP applications include body-in-white applications, seat tracks and seat recliners.
Complex Phase (CP) steels have higher yield strength and lower work hardening effect, compared to DP steels for same strength level. The CP steels have good fatigue properties when it comes to low cycle fatigue. Compared to DP, the CP steels offer better flanging and ISO hole expansion performance and these steels are suitable for applications where high strength, good bendability and stretch-flange ability is required.
Docol® Complex phase steel product offer:
*Available upon request.
Do you have manufacturability questions about these grades? Our Technical Support can provide specific CP and HER steel forming guidance for your automotive component.
Docol® CP steels are made according to VDA, EN, SSAB, and OEM specifications. Contact us if you cannot find a specific grade.
Safety engineers: Complex phase’s high yield-to-tensile-strength ratio provides high crash energy absorption.
Lightweighting engineers: Achieve thinner and lighter parts by specifying higher strength grades of CP steels.
Production engineers: Deliver complex shape components – e.g., stretched flanges with punched holes and tight radii – with high repeatability. Fully leverage cold-forming operations to save energy and processing time while increasing production line flexibility.
Buyers: Buy less material as you greatly reduce the number of defective components due to cracked sheared edges.
Sustainability officers: SSAB’s iron-ore based steelmaking is so CO2-efficient that our AHSS steels are equivalent to using recycled steel. And Fossil-Free Docol AHSS will be commercially available in 2026.
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.
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.
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.
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.
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.
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 (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 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.