If you’re designing lightweight, crash-resistant parts—especially for the automotive industry—DP 590 dual phase steel is a game-changer. As a key advanced high-strength steel (AHSS), it blends exceptional tensile strength with great formability, making it perfect for balancing safety and fuel efficiency. This guide breaks down everything you need to know to use it effectively.
1. Material Properties of DP 590 Dual Phase Steel
DP 590’s unique performance comes from its dual microstructure: soft ferrite (for formability) and hard martensite (for strength). Below is a detailed breakdown of its properties.
1.1 Chemical Composition
The alloy elements in DP 590 are carefully balanced to create its dual-phase structure. Values align with industry standards (e.g., EN 10346 or ASTM A1035):
| Element | Symbol | Composition Range (%) | Key Role in the Alloy |
|---|---|---|---|
| Carbon (C) | C | 0.06 – 0.10 | Promotes martensite formation; balances strength and ductility |
| Manganese (Mn) | Mn | 1.20 – 1.60 | Enhances hardenability; helps form the ferrite-martensite mix |
| Silicon (Si) | Si | 0.15 – 0.35 | Strengthens ferrite; acts as a deoxidizer during steelmaking |
| Chromium (Cr) | Cr | 0.10 – 0.30 | Improves corrosion resistance and refines grain structure |
| Aluminum (Al) | Al | 0.01 – 0.06 | Controls grain size; boosts formability and impact resistance |
| Titanium (Ti) | Ti | 0.01 – 0.05 | Prevents grain growth; enhances fatigue strength |
| Sulfur (S) | S | ≤ 0.015 | Kept low to avoid brittleness and improve weldability |
| Phosphorus (P) | P | ≤ 0.025 | Limited to prevent cold brittleness in crash scenarios |
| Nickel (Ni) | Ni | ≤ 0.20 | Trace amounts slightly improve toughness (not a primary element) |
| Molybdenum (Mo) | Mo | ≤ 0.10 | Minimal content; enhances high-temperature stability |
| Vanadium (V) | V | ≤ 0.05 | Tiny amounts refine martensite, boosting strength |
1.2 Physical Properties
These traits affect how DP 590 behaves in manufacturing and real-world use:
- Density: 7.85 g/cm³ (same as standard steel, but thinner gauges enable lighter designs)
- Melting point: 1450 – 1480°C (compatible with standard steel forming processes)
- Thermal conductivity: 42 W/(m·K) at 20°C (slightly lower than mild steel, but manageable for stamping)
- Specific heat capacity: 460 J/(kg·K) at 20°C (stable heat absorption during heat treatment)
- Thermal expansion coefficient: 12.5 μm/(m·K) (low expansion, critical for precision parts like body panels)
- Magnetic properties: Ferromagnetic (attracts magnets, useful for automated handling in factories)
1.3 Mechanical Properties
DP 590’s mechanical strength is its biggest advantage—especially for safety-focused parts. Values below are typical for cold-rolled sheets (per industry standards):
| Property | Typical Value | Test Standard |
|---|---|---|
| Tensile strength | 590 – 700 MPa | EN ISO 6892-1 |
| Yield strength | 340 – 440 MPa | EN ISO 6892-1 |
| Elongation | ≥ 20% | EN ISO 6892-1 |
| Reduction of area | ≥ 45% | EN ISO 6892-1 |
| Hardness (Vickers) | 170 – 210 HV | EN ISO 6507-1 |
| Hardness (Rockwell B) | 80 – 90 HRB | EN ISO 6508-1 |
| Impact toughness | ≥ 40 J (-40°C) | EN ISO 148-1 |
| Fatigue strength | ~300 MPa | EN ISO 13003 |
| Bending strength | ≥ 650 MPa | EN ISO 7438 |
1.4 Other Properties
- Corrosion resistance: Good (resists mild moisture and road salts; use zinc coating for automotive underbody parts)
- Formability: Excellent (soft ferrite lets it be stamped into complex shapes like door rings or bumpers)
- Weldability: Very good (low carbon content minimizes cracking; use standard MIG/MAG welding processes)
- Machinability: Fair (hard martensite can wear tools—use carbide inserts with cutting fluid)
- Wear resistance: Moderate (suitable for non-abrasive applications like body panels, not heavy machinery)
- Impact resistance: Strong (absorbs energy in crashes, making it ideal for safety components)
2. Applications of DP 590 Dual Phase Steel
DP 590’s mix of strength, formability, and lightweight potential makes it a top choice for high-strength, safety-critical applications. Here are its most common uses:
2.1 Automotive Industry (Primary Use)
Car manufacturers rely on DP 590 to meet crash safety and fuel efficiency goals:
- Body-in-white (BIW): Used for door frames, roof rails, and floor pans. A European automaker switched to DP 590 for BIW parts, cutting vehicle weight by 8% while improving crash test scores.
- Bumpers: Front and rear bumpers use DP 590—its impact resistance absorbs collision energy, protecting the vehicle’s core.
- Side impact beams: Door beams made from DP 590 reduce injury risk in side crashes; their tensile strength (590–700 MPa) prevents intrusion into the cabin.
- Suspension components: Control arms and knuckles use DP 590—its fatigue strength (~300 MPa) withstands constant road vibrations.
- Roll cages: Racing cars use DP 590 roll cages—lightweight yet strong enough to protect drivers in accidents.
2.2 Structural Components
Beyond automotive, DP 590 is used for lightweight, strong structures:
- Lightweight frames: Delivery vans and small trucks use DP 590 frames—lighter than mild steel, improving fuel economy.
- Safety barriers: Highway crash barriers use DP 590—its bending strength (≥650 MPa) bends on impact but doesn’t break, redirecting vehicles safely.
3. Manufacturing Techniques for DP 590 Dual Phase Steel
DP 590’s dual-phase structure is created through precise steelmaking and heat treatment. Here’s how it’s produced:
3.1 Steelmaking Processes
- Electric Arc Furnace (EAF): Most common for DP 590. Scrap steel is melted, then alloy elements (Mn, Cr, Al) are added to reach the target composition. EAF is flexible and reduces carbon emissions.
- Basic Oxygen Furnace (BOF): Used for large-scale production. Molten iron is mixed with oxygen to remove impurities, then alloy elements are added. BOF is faster but less flexible for custom compositions.
3.2 Heat Treatment (Critical for Dual Phase Structure)
The key step to create DP 590’s ferrite-martensite mix is inter-critical annealing:
- Cold rolling: The steel is rolled to thin gauges (1–3 mm) for automotive use.
- Inter-critical annealing: Heated to 750 – 800°C (between ferrite and austenite temperatures). This converts part of the ferrite to austenite.
- Rapid cooling: Quenched in water or air. The austenite transforms to martensite, creating the dual-phase structure.
- Tempering (optional): Heated to 200 – 300°C to reduce residual stress (used for parts like suspension components).
3.3 Forming Processes
DP 590 is shaped using processes that leverage its formability:
- Stamping: Most common for automotive parts. High-pressure presses shape DP 590 into door rings, bumpers, or body panels—its elongation (≥20%) lets it stretch without cracking.
- Cold forming: Used for simple parts like brackets. Cold rolling or bending creates shapes without heating.
- Press hardening (optional): For extra strength, some parts are heated to 900°C, stamped, and quenched—though DP 590 usually doesn’t need this (unlike UHSS).
3.4 Machining Processes
- Cutting: Laser or plasma cutting is used for trimming parts. Avoid oxy-fuel cutting (can damage the dual-phase structure).
- Welding: MIG/MAG welding with low-carbon filler metals works best. Preheat to 100 – 150°C to prevent cracking.
- Grinding: Used to smooth stamped parts. Use aluminum oxide wheels to avoid tool wear.
4. Case Study: DP 590 in Automotive Side Impact Beams
A global automaker faced a problem: their mild steel side impact beams were heavy, hurting fuel efficiency, and didn’t meet new crash safety standards. They switched to DP 590—and solved both issues.
4.1 Challenge
The automaker’s compact cars needed to pass Euro NCAP side crash tests (protecting occupants from intrusions) while reducing weight by 10% to meet emissions goals. Mild steel beams were 3.5 kg each, too heavy, and had low tensile strength (350 MPa), leading to excessive cabin intrusion.
4.2 Solution
They switched to DP 590 side impact beams, using:
- Stamping: Shaped into a curved beam design (DP 590’s formability let it handle the complex shape).
- Zinc coating: Added a 10 μm zinc layer for corrosion resistance (critical for door beams).
- Welding: MIG-welded to the door frame (DP 590’s weldability ensured strong joints).
4.3 Results
- Weight reduction: Beams weighed 2.2 kg each—37% lighter than mild steel.
- Safety improvement: Cabin intrusion dropped by 40% in crash tests (DP 590’s tensile strength prevented bending).
- Cost savings: Fuel efficiency improved by 2% per vehicle, and production costs stayed the same (DP 590 is only 15% more expensive than mild steel, but the weight savings offset this).
5. Comparative Analysis: DP 590 vs. Other Materials
How does DP 590 stack up against common alternatives for high-strength applications?
| Material | Tensile Strength | Elongation | Density | Cost (vs. DP 590) | Best For |
|---|---|---|---|---|---|
| DP 590 Dual Phase Steel | 590–700 MPa | ≥20% | 7.85 g/cm³ | 100% (base) | Automotive safety parts (beams, BIW) |
| Mild Steel (SPCC) | 300–400 MPa | ≥30% | 7.85 g/cm³ | 85% | Low-stress parts (inner panels) |
| HSLA Steel (H340LA) | 340–440 MPa | ≥25% | 7.85 g/cm³ | 90% | Structural parts (frames) |
| UHSS (22MnB5) | 1500–1800 MPa | ≥10% | 7.85 g/cm³ | 180% | Ultra-safe parts (A-pillars) |
| Aluminum Alloy (6061) | 310 MPa | ≥16% | 2.70 g/cm³ | 300% | Very lightweight parts (hoods) |
| Composite (Carbon Fiber) | 3000 MPa | ≥2% | 1.70 g/cm³ | 1000% | High-end parts (racing car bodies) |
Key takeaway: DP 590 offers the best balance of strength, formability, and cost for most automotive safety parts. It’s lighter than mild steel (when using thinner gauges) and cheaper than aluminum or composites.
Yigu Technology’s Perspective on DP 590 Dual Phase Steel
At Yigu Technology, DP 590 is our top recommendation for automotive clients needing to balance safety and lightweight design. We’ve supplied DP 590 sheets for side impact beams and BIW parts for 8+ years, and its consistent formability and impact resistance always meet strict standards. We often suggest zinc-nickel coating for underbody parts to boost corrosion resistance. For automakers transitioning to electric vehicles (EVs), DP 590 is a cost-effective way to reduce weight without sacrificing safety—critical for extending EV range.
FAQ About DP 590 Dual Phase Steel
1. Can DP 590 be used for EV battery enclosures?
Yes—its tensile strength (590–700 MPa) and impact resistance protect batteries from crashes. We recommend pairing it with a corrosion-resistant coating (like galvannealing) to prevent rust from road salts.
2. Is DP 590 more expensive than mild steel?
Yes, but only by 10–15%. The weight savings (30–40% for the same strength) reduce fuel costs or EV range anxiety, making it a better long-term value. For high-volume production, the cost difference is even smaller.
3. Can DP 590 be welded to other steels?
Absolutely. It welds well to mild steel or HSLA steel using standard MIG/MAG welding. Use filler metals with low carbon content (e.g., ER70S-6) and avoid overheating (keeps the dual-phase structure intact).
