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

Dual phase steels are mostly a ferritic matrix with islands of martensite. Automotive DP steels have excellent global ductility because of the mostly continuous soft ferrite phase.  When dual phase steels are deformed, the strain is concentrated in the lower-strength ferrite that surrounds the harder 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.

• 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.