420 780DP Dual Phase Steel for Structural and Heavy Parts

Perfect Balance of High Strength and Lightweight

Yield strength: 420–550 MPa; Tensile strength: ≥780 MPa, significantly higher than conventional low-carbon steel.
Low yield-to-tensile ratio (0.5–0.7): The material retains a long work-hardening stage after yielding, absorbing more collision energy and enhancing structural safety. oWeight reduction: 20–30% lighter than ordinary steel at equivalent strength, supporting lightweighting in new energy vehicles, construction machinery and other fields.

Excellent Formability and Processability

Dual-phase microstructure (ferrite + martensite): Provides high elongation (≥14–17%) and complex-shape forming capability, suitable for deep drawing and stamping.
Low springback: Optimized surface quality (FB/FC grades) via cold rolling reduces post-processing deformation and improves dimensional accuracy.
Versatile processing compatibility: Supports shearing, bending, punching, laser cutting, etc. Zinc coatings (e.g., HC420/780DPD+Z) resist flaking during forming, extending service life.

Superior Corrosion Resistance and Weldability

oHot-dip galvanized / electro-galvanized finish: Pure zinc coating (Z) effectively resists atmospheric and humid corrosion, ideal for outdoor structural parts (e.g., building purlins, bridge components).
oWelding compatibility: Supports resistance spot welding, laser welding and conventional processes. Welded joints achieve shear strength of 14.88 kN with no embrittlement in the heat-affected zone, meeting automotive safety component welding standards.

Excellent Impact Resistance and Energy Absorption

High work-hardening exponent: Continuously strengthens under impact or dynamic load, absorbing energy and preserving structural integrity.
Typical application validation: A new energy vehicle model used 420/780DP for B-pillars, improving side-impact safety by 30% while maintaining normal door opening after collision.

Mechanical Properties

Property	Value Range	Test Standard
Yield Strength (ReL/Rp0.2)	420–550 MPa	GB/T 228.1 (P6 specimen)
Tensile Strength (Rm)	≥780 MPa	JIS Z2241 (No.5 specimen)
Elongation After Fracture (A80)	≥14–17%	−4% tolerance when thickness ≤0.5 mm
Surface Roughness (Ra)	<0.9 μm (bright surface)	—
Surface Quality Grade	FB (higher grade), FC (high grade)	Q/BQB 418—2023

Chemical Composition (wt%)

Element	C	Si	Mn	P	S	Al	Others (Nb/Ti/Cr/Mo/B)
Max. Content	0.18	0.9	2.5	0.04	0.015	≥0.005	≤1.5% (total)

Core Advantages of 420/780DP Dual-Phase Steel

Balanced strength and ductility, easy processing: Combines high strength and elongation for complex stamping and bending, effectively reducing springback and scrap rates.
Extreme lightweighting, cost and efficiency improvement: 10–30% weight reduction at equal strength, lowering material, transport and installation costs while improving end-use efficiency.
Weather and fatigue resistance, long durability: Galvanized coating passes 800–1000 hours of salt spray testing; excellent fatigue performance suits outdoor and long-term load conditions.
Excellent weldability for high-volume production: Compatible with multiple welding methods; weld strength reaches 85% of base metal, meeting mass production requirements.
Customized specifications, flexible delivery: Thickness 0.5–3.0 mm available; supports cut-to-length and slitting to quickly adapt to various working conditions.

About Nature Steel Group

Nature Steel Group is a modern steel enterprise specialized in R&D and production of high-strength steel and dual-phase steel. Its main products include dual-phase steel (such as 420/780DP), high-strength cold-rolled steel and galvanized steel, with full specifications and customization for structural and heavy-duty parts in automotive, construction machinery and construction fields.
The company is certified to ISO9001 and ISO14001, with full-process precise control over performance, surface quality and dimensional tolerance. It is recognized as an environmental performance-compliant enterprise, having established long-term cooperation with numerous OEMs and engineering institutions; its products are widely used in key projects.
Supported by professional technical and after-sales teams, it provides one-stop services including material selection, processing support and customized production, balancing quality and delivery efficiency to help customers reduce costs and improve efficiency.