Dual-phase and low-alloy advanced high-strength steel for automotive crash structures. HC420/780DP carries a ferrite + martensite microstructure, guaranteeing ≥780 MPa tensile with ≥14% elongation — the strength-to-ductility balance that lets a B-pillar absorb crash energy without fracturing.
Conventional high-strength steel trades ductility for strength. Dual-phase steel breaks that trade by putting two microstructures to work at once.
The dual-phase microstructure. DP steel is annealed in the intercritical range, then rapidly cooled to transform austenite into martensite within a ferrite matrix. Ferrite provides formability and continuous yielding; martensite provides strength.
The grade ladder. DP runs from HC250/450DP (450 MPa) to HC1150/1400DP (1400 MPa). As tensile rises, elongation falls — HC250/450DP ≥28%, HC980/1180DP ≥8%.
Beyond DP: the LA grades. HC340LA–HC600LA are micro-alloyed ferritic-bainitic steels (Nb/V/Ti) with high yield, good bendability and weldability — but without DP's crash energy absorption. Choose DP for crash rails and B-pillars; LA for chassis brackets and seat structures.
Most specification errors on this family are made at the microstructure boundary and the coating boundary, not in the strength grade.
HSLA (SAPH440, S355MC) has high yield-to-tensile ratio and a distinct yield point. DP has low ratio (0.5–0.7), continuous yielding and high work-hardening.
Choose DP for crash energy; HSLA for cost and static strength.Cold-rolled AHSS is formed at room temperature and used as-supplied. Press hardening (22MnB5+AS) is formed hot and quenched in-die to 1500 MPa — higher strength at thinner gauge, but needs a hot-stamping line.
Choose cold-rolled AHSS for room-temp forming; press hardening for 1500 MPa at thin gauge.Bare (oil-coated) is cheaper for painted, protected body structure. Coated (+Z galvanized, +ZF galvannealed, +ZM zinc-magnesium) is required for underbody exposure or OEM corrosion specs.
Choose coated for underbody moisture; bare for painted, protected parts.Indicative values per GB/T 20887 and equivalent standards — confirmed on the MTC.
| Grade | C % | Si % | Mn % | P % | S % | Cr % | Mo % | Nb+V+Ti % |
|---|---|---|---|---|---|---|---|---|
| HC420/780DP | ≤0.15 | ≤0.50 | ≤2.20 | ≤0.030 | ≤0.015 | ≤0.60 | ≤0.30 | ≤0.15 |
| HC550/980DP | ≤0.20 | ≤0.60 | ≤2.40 | ≤0.030 | ≤0.015 | ≤0.80 | ≤0.40 | ≤0.15 |
| HC980/1180DP | ≤0.23 | ≤0.80 | ≤2.60 | ≤0.030 | ≤0.015 | ≤1.00 | ≤0.50 | ≤0.15 |
| HC340LA | ≤0.10 | ≤0.50 | ≤1.50 | ≤0.025 | ≤0.020 | — | — | ≤0.22 |
| B400/780DP | ≤0.15 | ≤0.50 | ≤2.20 | ≤0.030 | ≤0.015 | ≤0.60 | ≤0.30 | ≤0.15 |
DP grades may also contain small additions of B (boron) for hardenability.
These are guaranteed minimums per the governing standard — the MTC documents actual yield, tensile and elongation per coil.
| Grade | Microstructure | Yield MPa (min) | Tensile MPa (min) | Elongation % (min, A80) | Typical use |
|---|---|---|---|---|---|
| HC250/450DP | Dual-phase | 250 | 450 | 28 | Moderate-strength structural, wheels |
| HC340/590DP | Dual-phase | 340 | 590 | 20 | Body structure, closure inners |
| HC420/780DP | Dual-phase | 420 | 780 | 14 | B-pillar reinforcements, rockers, crash rails |
| HC550/980DP | Dual-phase | 550 | 980 | 10 | High-strength crash structures, sill reinforcements |
| HC980/1180DP | Dual-phase | 980 | 1180 | 8 | Ultra-high-strength structural, bumper beams |
| HC1150/1400DP | Dual-phase | 1150 | 1400 | 6 | Maximum-strength cold-rolled DP, limited forming |
| HC340LA | Ferritic-bainitic | 340 | 410–530 | 21 | Chassis brackets, seat structures, suspension arms |
| HC420LA | Ferritic-bainitic | 420 | 480–600 | 18 | High-yield structural, load-bearing components |
Elongation values are typical for 1.0 mm thickness; thicker gauges may carry slightly different bands per the standard.
Equivalents approximate; confirm against your standard.
| GB / Baosteel | EN 10338 | VDA 239-100 | ASTM / AISI | Notes |
|---|---|---|---|---|
| HC250/450DP | HCT450X | CR450Y250-DP | — (DP 450) | Entry dual-phase |
| HC340/590DP | HCT590X | CR590Y340-DP | — (DP 590) | Mid-strength dual-phase |
| HC420/780DP / B400/780DP | HCT780X | CR780Y420-DP | — (DP 780) | The volume automotive structural grade — near-universal interchange |
| HC550/980DP | HCT980X | CR980Y550-DP | — (DP 980) | High-strength dual-phase |
| HC980/1180DP | HCT1180X | CR1180Y980-DP | — (DP 1180) | Ultra-high-strength dual-phase |
| HC340LA | HCT340LA | CR340LA | — (HSLA 340) | Low-alloy micro-alloyed |
| HC420LA | HCT420LA | CR420LA | — (HSLA 420) | High-yield low-alloy |
HC420/780DP, HCT780X (EN) and CR780Y420-DP (VDA) are the same dual-phase material under different standards — the choice is governed by your drawing's specified standard and audit requirements.
Where microstructure shows up in crash performance.
The test: HC420/780DP or HC550/980DP stamped into B-pillar reinforcements, spot-welded. Must absorb side-impact energy by progressive deformation. See our press-hardening B-pillar application.
The test: HC340/590DP or HC420/780DP roll-formed into crash rails. Must buckle in controlled progressive mode.
The test: HC550/980DP, 1.0–1.4 mm, formed into closed-section rockers. Tight bend radii demand stretch-flangeability.
The test: HC340LA or HC420LA, 1.5–2.5 mm, stamped and welded. Carry static/fatigue load — need high yield, bendability and weldability.
All in-house in Shanghai — one contract, one MTC, one contact.
AHSS coil slit from 1248 mm parent to your width, including narrow progressive-die widths. See the edge burr guide.
Coil leveled to remove set and crossbow — critical for AHSS where residual stress causes shape distortion after blanking.
Bare AHSS checked for defects and oil weight; coated (+Z/+ZF/+ZM) checked for coating weight, adhesion and class. See the surface finish guide.
Gauge, width, surface and mechanicals per coil; MTC with chemistry, yield, tensile and elongation issued before export. See the MTC guide.
22MnB5+AS Al-Si coated cold-rolled coil for hot stamping to 1500 MPa — the hot-formed alternative for maximum-strength body parts at thin gauge.
Browse press hardening steel →
SAPH, QSTE, S-MC and BR grades at 1.5–12 mm — the thicker-gauge HSLA and hot-stamping counterpart for chassis and structural parts.
Browse pickled coil →
Galvanized +Z, Galvalume +AZ and Magnelis +ZM — including coated DP and LA AHSS grades for underbody and corrosion-exposed structural parts.
Browse coated steel →
SPCC, DC01–DC06 and SAE1010–1050 at 0.03–350 mm — the formability-first range for non-structural panels and precision-formed parts.
Browse cold rolled strip →Include grade, gauge, tonnage and destination.