Abstract
Material Engineer's Handbook for NEV Production – AHSS, Hot Stamping Steel & Gigacasting Die Steel Selection
Material requirements for battery electric, plug-in hybrid and range-extended EVs differ greatly from internal combustion vehicles. Demands for lightweight design, high-voltage electromagnetic shielding, battery crash protection and gigacasting have pushed constant upgrades to steel, aluminum and specialty alloy families. Drawing on GB, EN and JIS material standards, plus mass production data from OEMs including Tesla, BYD, NIO and Volkswagen, this guide lays out grade selection rules covering five core segments: BIW structural steel, battery system metals, traction motor electrical steel, chassis stamping & forging steel, and NEV-specific tool steel. All grade tables, mechanical property data and component matching charts are retained. The content serves domestic design & procurement engineers while fitting Google cross-border search, and works as daily reference for material specification, mill quotation and mold development work.
Core Material Selection Differences Between ICE & NEV + Vehicle Material Mass Breakdown
Four Major Differentiators
NEVs carry high-voltage battery packs operating at 300–700V. Requirements for curb weight management, crashworthiness, NVH performance and EMI shielding set them apart from ICE cars and define proper steel grade selection:
Power architecture: ICE vehicles rely on combustion engines, while NEVs carry 400–800kg battery packs. Undercarriage crash protection becomes a top priority, requiring large volumes of 1500MPa hot-stamped boron steel.
Lightweight targets: Vehicle mass reduction directly boosts driving range, so mixed use of high-strength steel, aluminum and magnesium alloys keeps growing.
Noise control: Without engine noise to mask body vibration, structural steels must be paired with energy-absorbing, vibration-dampening designs.
Electromagnetic shielding: Metal housings for high-voltage wiring, battery enclosures and power electronics form Faraday cages to cut EMI. Standard material selection logic across the industry: Lightweight construction to extend range → balance material costs between steel, aluminum and composites → deploy ultra-high strength steel for battery crash safety → adopt specialty alloys for thermal management solutions → use metallic enclosures for EMI shielding.
Material Mass Distribution of Mass-Market BEVs
Data from mass-produced models like Tesla Model Y and BYD Seal provides reliable industry benchmarks for material weight share per vehicle:
| Material Category | Mass Per Vehicle | BIW Weight Percentage |
|---|---|---|
| AHSS & UHSS | 200–350kg | 25%–35% |
| Conventional HSS & Mild Steel | 350–500kg | 40%–50% |
| Aluminum (Sheet, Extrusion, HPDC Casting) | 100–250kg | 15%–25% |
| Magnesium Die Castings | 5–30kg | 1%–3% |
| Carbon Fiber Reinforced Polymer (CFRP) | 10–50kg | 1%–5% |
| Plastics & Modified Composite Materials | 80–150kg | 10%–15% |
Industry observation: Tesla Model Y's gigacast aluminum assemblies replace over 70 stamped steel components and cut overall BIW mass by roughly 20%.
Evolution of NEV BIW Steel Grades
Over the past 15 years, tensile strength of automotive body steel for EVs has risen steadily, with new grades exceeding 2000MPa:
| Generation | Timeframe | Dominant Materials | Tensile Strength Range |
|---|---|---|---|
| First-gen Early EVs | 2010–2015 | Mild steel + 340–590 conventional HSS | 270–590MPa |
| Second-gen Mass-Production Vehicles | 2016–2020 | Conventional HSS, AHSS, aluminum hood panels | 270–980MPa |
| Third-gen Current Mainstream Models | 2021–2024 | AHSS, UHSS, hot-stamped boron steel, aluminum-magnesium hybrid parts | 270–1500MPa |
| Fourth-gen New Platforms (2025 onwards) | 2025+ | 2000MPa ultra high hot-stamping steel, multi-material assemblies | 270–2000MPa |
Full Grade Selection for BIW Structural Steel (All Reference Tables Retained)
Body steel is split into five families by tensile strength and metallurgical microstructure: mild steel, conventional HSS, AHSS, UHSS and hot-stamped boron steel. Separate grades are specified for different body components.
Mild Steel (DC Series for Low-Stress Draw Components)
| Grade | Typical Chemical Composition | Tensile Strength (MPa) | Application |
|---|---|---|---|
| DC01 | 0.04% C, 0.20% Mn | 270–410 | Low-stress interior body panels |
| DC04 | 0.04% C, 0.18% Mn | 270–350 | Standard deep drawing inner panels |
| DC06 | 0.02% C, 0.15% Mn | 270–350 | Extra deep drawing complex interior parts |
| SPCE (JIS Standard) | Matches DC04 chemistry | 270–350 | Body sheets for Japanese OEM platforms |
Conventional HSLA High Strength Steel
| Grade | Tensile Strength (MPa) | Application |
|---|---|---|
| HC340LA | 340–460 | General body reinforcements |
| HC380LA | 380–480 | Chassis cross members, sill inner plates |
| HC420LA | 420–520 | Inner pillar reinforcements |
| HSLA340 / HSLA590 | 340–590 | Universal structural components |
| SAPH440 (JIS Standard) | 440 | Chassis stampings for Korean & Japanese vehicles |
AHSS: DP / TRIP / CP / QP Metallurgy Families
Primary grades for crash energy absorption, door anti-intrusion beams and longitudinal rails, balancing strength and formability.
Dual Phase (DP) Steel
| Grade | Typical Weight Percent Composition | Tensile Strength (MPa) | Component Use |
|---|---|---|---|
| DP590 | 0.10% C, 1.50% Mn, 0.50% Si, 0.05% Nb | 590 | Floor cross members, lower longitudinal rails |
| DP780 | 0.13% C, 1.80% Mn, 0.30% Si, 0.03% Nb | 780 | Front rails, outer B pillar panels |
| DP980 | 0.15% C, 2.00% Mn, 0.50% Si, 0.05% Nb | 980 | Side impact reinforcements |
| DP1180 | 0.17% C, 2.20% Mn, 0.30% Si, 0.04% Ti | 1180 | Door intrusion beams |
2 TRIP (Transformation-Induced Plasticity) Steel
| Grade | Tensile Strength (MPa) | Application Location |
|---|---|---|
| TRIP590 | 590 | Crash energy absorbing structures |
| TRIP780 | 780 | Front crush rails |
| TRIP980 | 980 | B pillars, rocker reinforcements |
Complex Phase (CP) & Quench & Partition (QP) Steel
| Grade | Tensile Strength (MPa) | Application |
|---|---|---|
| CP800 | 800 | Wheel rims, bumper reinforcements |
| CP1000 | 1000 | Mid B pillar, side rockers |
| QP980 | 980 | Critical crash safety parts |
| QP1180 | 1180 | Door anti-intrusion beams |
UHSS: Martensitic & Hot-Stamped Boron Steel
English: Mandatory for battery perimeter shielding and core safety cage components, quenched tensile strength up to 2500MPa:
| Grade Family | Quenched Tensile Strength (MPa) | Matching Components |
|---|---|---|
| MS1180 Martensitic Steel | 1180 | Side impact beams |
| MS1300 Martensitic Steel | 1300 | Rocker reinforcements |
| MS1500 Martensitic Steel | 1500 | Heavy anti-intrusion components |
| 22MnB5 Hot-Stamped Steel | 1500 | A/B/C pillars, rockers, bumpers, battery guards |
| 27MnCrB5 Hot-Stamped Steel | 1700 | Premium vehicle safety cage parts |
| 30MnB5 Hot-Stamped Steel | 1800 | Tesla Cybertruck exoskeleton components |
| Custom Tesla Giga-Steel | 2500+ | Ultra-light load-bearing body structures |
All A/B/C pillars, roof rails and rockers use 22MnB5 hot-stamped steel. Upper front rails adopt TRIP980, while lower front rails use 22MnB5. Door intrusion beams and bumper beams are formed from 1500MPa boron steel. Hood and outer door panels use 6016 / 6022 aluminum alloy. Battery lower shields combine extruded aluminum profiles with 22MnB5 protective steel plates.
3 Metal Material Selection for Battery Systems (Steel Housings, Aluminum, Internal Conductive Metals)
Battery packs represent the core safety component of NEVs. Selected materials must satisfy four key requirements simultaneously: lightweight design, crash resistance, thermal dissipation and EMI shielding. This section covers pack enclosures, module internal hardware and cooling plates separately.
Battery Enclosure Material Comparison Table
| Enclosure Material | Lightweight Rating | Cost Tier | Crash Protection | Thermal Performance | EMI Shielding | OEM Adoption |
|---|---|---|---|---|---|---|
| Extruded Aluminum + Aluminum Sheet | ★★★★★ | Mid-High | Good | Best | Moderate | Tesla, BYD, NIO |
| Stamped Steel Enclosure | ★★★ | Lowest | Excellent | Average | Early EVs, VW ID Series | |
| Gigacast Aluminum Housing | ★★★★ | High | good | Excellent | Moderate | New Tesla models, Xiaomi SU7, NIO |
| SMC Composite | ★★ | high | Fair | poor | Weak | Low-volume niche vehicles |
| CFRP Composite | ★★★★★ | Very High | Fair | poor | Weak | Ultra-luxury limited editions |
Steel Grades for Battery Enclosures
| Steel Grade | Material Family | Installation Location |
|---|---|---|
| DC04 / DC06 | Deep drawing mild steel | Battery top cover, internal supports |
| HSLA340 / HSLA380 | Low alloy HSS | Pack bottom frame |
| DP590 / DP780 | AHSS | Side crash reinforcement ribs |
| 22MnB5 Hot-Stamped Steel | UHSS boron steel | Battery side crash guards |
Common Aluminum Alloys for Battery Housings
| Aluminum Grade | Forming Process | Application Area |
|---|---|---|
| 6005 / 6063 | Extrusion | Main pack longitudinal & cross rails |
| 6082 / 7003 | High-strength extrusion | Crash-side profiles |
| 5182 / 5754 | Stamped sheet | Bottom cooling-integrated trays |
| A380 / C611 | High pressure die casting | Tesla gigacast battery trays |
| 6061-T6 | Stamped sheet | Pack top cover |
Internal Metallic Parts for Battery Modules
| Component | Standard Material | Supplementary Note |
|---|---|---|
| Cell support frame | PA66+GF35 glass-filled plastic | Insulated injection molded frame |
| Cell spacer foam | PP / PE foam | Thermal buffer & shock absorption |
| High voltage busbar | T2 / T3 copper; 6061 aluminum alternative | Copper offers superior conductivity, aluminum cuts mass & cost |
| Module compression end plate | 6061 / 6082 aluminum sheet | Uniform stacking compression |
| Liquid cooling plate | Brazed 3003 aluminum | Standard liquid cooling substrate |
Cell Core Metallic Substrates
While not structural steel, current collector and casing metals form critical battery components: Cathode current collector: 15–20μm aluminum foil; Anode current collector: 8–15μm copper foil 4680 cylindrical cells: Aluminum casing with steel base support; BYD blade prismatic cells: Aluminum housing; Pouch cells: Aluminum laminated composite film
Steel & Alloys for E-Drive Systems (Motor, Inverter, Reducer)
Cast Aluminum Alloys for Traction Motor Housings
| Alloy Grade | Forming Process | Vehicle Segment Fit |
|---|---|---|
| A380 / A383 | High pressure die casting | Mass-market ICE & BEV passenger cars |
| A356 | Die casting / Semi-solid casting | Premium performance vehicles |
| 6061-T6 | Forging + finish machining | Supercars, high-performance EVs |
| AZ91D | Die casting | Lightweight concept vehicles |
Standard A380 chemical makeup: Balance Al, 7.5–9.5% Si, 3.0–4.0% Cu, 0.05–0.50% Mg, 0.7–1.1% Fe, 0.20–0.50% Mn, 0.5–1.5% Zn
Non-Oriented Electrical Steel for Motor Cores (Range Determinant Material)
| Electrical Steel Grade | Sheet Thickness | Core Loss (W/kg @1.5T, 50Hz) | Motor Application Segment |
|---|---|---|---|
| 50W470 | 0.50mm | ≤4.7 | Entry-level low-cost motors |
| 35W440 | 0.35mm | ≤4.4 | Standard mainstream traction motors |
| 30W360 | 0.30mm | ≤3.6 | Mid-to-high range long-range EVs |
| 25W300 | 0.25mm | ≤3.0 | 800V high-performance platforms |
| 20W250 | 0.20mm | ≤2.5 | Flagship high-efficiency motors |
| 50JN800 / 35JN300 | Non-oriented lamination | ≤8.0 / ≤3.0 | Dedicated rotor laminations |
Base composition of non-oriented electrical steel: 2.0–3.5% Si, 0.2–0.8% Al, ≤0.005% C, 0.10–0.30% Mn, ≤0.003% S, balance Fe.
Quenched & Tempered / Carburized Steel for Motor Shafts
| Steel Grade | Heat Treatment Route | Applicable Torque Band |
|---|---|---|
| 20CrMnTi / SCM415 | Carburizing & quenching | Low-to-medium torque motors |
| 42CrMo / SCM440 | Quench & temper | High torque traction motors |
| 40Cr / SCr440 | Quench & temper | Standard passenger car motors |
| 316L Stainless | Solution treatment | Corrosion-resistant specialty motors |
Standard 42CrMo composition: 0.38–0.45% C, 0.17–0.37% Si, 0.50–0.80% Mn, 0.90–1.20% Cr, 0.15–0.25% Mo, balance Fe.
Inverter & DC-DC Converter Housings
A380 die cast aluminum serves as standard housing material. High-power units use finned 6063 extruded aluminum for enhanced heat dissipation. Magnesium die castings are adopted for lightweight designs.
Chassis Steel & Forged Alloys (Subframe, Suspension, Brake, Steering)
Subframe Material Options
| Material Combination | Forming Method | OEM Field Applications |
|---|---|---|
| HSLA / DP780 / 22MnB5 steel | Stamped & welded | BYD, XPeng, Li Auto mass-market models |
| 6061 + 6082 extrusion + cast connection nodes | Extrusion assembly | High-end Tesla & NIO vehicles |
| Mixed steel-aluminum construction | Stamping + aluminum forging | Mid-tier cost-efficient platforms |
Suspension Component Material List
| Chassis Component | Primary Material | Low-Cost Alternative |
|---|---|---|
| Control arm | 6061-T6 forged aluminum | Stamped DP780 steel, GGG60 ductile iron |
| Steering knuckle | 6061-T6 forged aluminum | 40Cr / 42CrMo forged steel, GGG70 cast iron |
| Suspension coil spring | 55CrMn spring steel | 60Si2Mn |
| Anti-roll stabilizer bar | 55CrMn spring steel | Hot bent 60Si2Mn |
| Shock absorber piston rod | Carburized 20CrMnTi | Low carbon tempered steel |
Brake, Steering & Wheel Materials
Brake discs mainly use HT250 gray cast iron. Aluminum matrix composite and carbon-ceramic discs are fitted on high-performance vehicles. Brake calipers are standard A380 die cast aluminum. Steering system: Steering column tubes use 20CrMnTi; rack bars adopt 40Cr; pinion gears are carburized 20CrMnTi. Wheels: Mass-market vehicles use A356-T6 cast aluminum. Premium models run 6061-T6 forged aluminum. Entry-level cars use stamped steel wheels; flagship supercars adopt magnesium or carbon fiber wheels.
NEV-Specific Tool Steel (Gigacasting, Hot Stamping, Stamping, Injection Molds)
NEV production lines introduce 9000-ton gigacasting presses and see sharply higher demand for 22MnB5 hot-stamping dies. Tool steel selection differs significantly from ICE vehicle programs; full hardness and application tables are retained below.
Gigacasting Die Steel Grades
| Die Component | Recommended Grade | Working Hardness (HRC) | Selection Reason |
|---|---|---|---|
| Main die block | QRO90 Supreme / DH2F | 44–48 | Excellent thermal fatigue resistance for 80–120 ton large dies |
| Cost-effective mass production option | ESR H13 / 1.2344 | 44–48 | Balanced raw material cost and service life |
| Cavity inserts | ESR-refined H13 | 46–50 | High cleanliness to eliminate casting surface pitting |
| Sprue bush & ejector pins | H13 / SKD61 | 48–54 | Resist molten aluminum erosion |
| Die base support block | S50C / S55C carbon steel | 28–32 | Low-cost structural backing |
Tool Steel for 22MnB5 Hot Stamping Dies
| Die Component | Steel Grade | Hardness Range (HRC) | Working Condition Note |
|---|---|---|---|
| Hot stamping die body | ESR H13 (1.2344) | 46–50 | Continuous thermal cycling at 800–950°C |
| Extended service life upgrade | QRO90 | 46–50 | Reduced frequency of heat crack polishing |
| Post-hot-stamping trim dies | DC53 / D2 cold work steel | 58–62 | Cut quenched 1500MPa boron steel blanks |
Stamping Tool Steel for Aluminum & UHSS Blanks
| Stamping Blank Material | Insert Steel Grade | Matching Coating |
|---|---|---|
| 6016 / 5754 aluminum outer panels | DC53 | CrN / DLC anti-galling coating |
| DP / QP 1180 UHSS | V4 / ASP2060 PM steel | TiAlN high temperature wear coating |
| Class A aluminum hood draw die | GGG70L ductile iron base + DC53 inserts | DLC mirror finish coating |
Injection Mold Steel for Battery Plastic Components
Large battery housing mold bodies use pre-hardened 1.2738HH (38–40HRC), which accepts chemical graining without secondary heat treatment. Mirror optical and flame-retardant corrosive plastic inserts adopt ESR S136 stainless steel to resist acidic decomposition gases released during molding. H13 inserts with nitriding treatment are fitted to high-abrasion zones for PA66+glass fiber materials to slow fiber scratching. Small slides and cores use DC53 / SKD11 for balanced impact toughness and wear resistance.
Cold Heading Steel for High-Voltage Battery Fasteners
M2 / SKH-9 high speed steel is standard for mass production dies making Grade 10.9 / 12.9 EV high-voltage bolts. For lines producing over one million fasteners annually, ASP2060 PM high speed steel reduces punch breakage incidents.
Material Cost Reference 2024–2026 EXW China, USD/kg
Structural Steel Sheet Pricing
| Steel Material | Form | Price Band (USD/kg) |
|---|---|---|
| DC04 cold rolled steel | Coil | 0.7–1.0 |
| HSLA340 / HSLA590 | Coil | 0.8–1.2 |
| DP780 dual phase steel | Coil | 1.0–1.4 |
| DP980 UHSS | Coil | 1.2–1.6 |
| DP1180 martensitic steel | Coil | 1.4–2.0 |
| 22MnB5 hot-stamped blank | Laser cut sheet | 1.3–1.8 |
| 30MnB5 ultra hot-stamping steel | Sheet | 1.8–2.5 |
| 5182 aluminum stamping sheet | Stamping sheet | 2.5–3.5 |
| 6016-T4 aluminum outer panel sheet | Stamping sheet | 3.0–4.5 |
| 6061-T6 aluminum extrusion profile | Extruded profile | 3.5–5.0 |
| A380 die cast ingot | Cast ingot | 3.0–4.0 |
| AZ91D magnesium ingot | Die casting feedstock | 4.0–6.0 |
| 30W360 electrical steel | Coil | 3.0–4.5 |
| 20W250 ultra-thin electrical steel | Coil | 6.0–10.0 |
BIW Cost Per Kilogram by Material Mix
| Material Assembly Scheme | Cost Per Kilogram (USD) | Matching Vehicle Lines |
|---|---|---|
| Full mild steel + conventional HSS | 0.9–1.3 | Entry low-cost EVs |
| Mixed HSS + limited AHSS | 1.2–1.8 | BYD Dolphin, Li Auto L-series |
| AHSS / UHSS + aluminum closures | 1.8–2.8 | Tesla Model Y, NIO ET5 / ET7 |
| Extensive gigacast aluminum body | 2.8–4.5 | Xiaomi SU7, Lucid premium EVs |
| Multi-material with CFRP | 5.0–15.0 | Limited production flagship sports cars |
Industry Material Trends Post 2025
Gigacasting technology expands rapidly, with growing installation of 9000-ton presses. Stamped steel component counts per vehicle drop 30–50%, lifting demand for hot work tool steel such as QRO90 and ESR H13. 2000MPa grade hot-stamped boron steel enters mass production, with Tesla custom Giga-Steel deployed to cut mass while boosting battery side crash protection. Multi-material BIW designs become standard, and steel mills release dedicated consumables for dissimilar steel-aluminum welding. CTC and CTP battery-chassis integration eliminates conventional stamped floor panels, replacing them with extruded aluminum paired with hot-stamped protective steel. Demand for ultra-thin 0.20mm and 0.25mm low core loss electrical steel rises for 800V high-voltage platforms, delivering modest range improvements per charge. OEMs source higher volumes of EAF recycled automotive HSS to lower carbon footprints. PM tool steel penetration grows in UHSS stamping and high-volume fastener cold heading lines.
Standard Material Strategies of Major OEMs
| OEM Brand | Core Material Roadmap | Primary Steel & Alloy Grades |
|---|---|---|
| Tesla | Gigacast aluminum + ultra-high strength boron steel | 30MnB5, 6005 / 6082 extrusion, 6016 sheet |
| BYD | Steel-dominant, selective aluminum lightweighting | DP980, 22MnB5, A380 die cast |
| NIO | Premium steel-aluminum hybrid | DP980, 22MnB5, 6005 extrusion |
| XPeng | Cost-focused HSS architecture | HSLA590, DP780 primary grades |
| Li Auto (Range Extender) | Steel-heavy with minor aluminum parts | HSLA590, 22MnB5 hot-stamped |
| Xiaomi SU7 | Premium all-aluminum + local high strength steel | 22MnB5, 6016, 6082 extrusion |
| VW MEB Platform | Balanced steel & aluminum | DP780, 22MnB5, 6005 extrusion |
| BMW i Series | CFRP + aluminum intensive | CFRP, 6005, A380 die cast |
Material Demand Comparison: ICE vs BEV
| Vehicle Assembly | Conventional ICE Vehicle | Battery Electric Vehicle | Industry Shift Trend |
|---|---|---|---|
| Engine block | Cast iron / aluminum | Eliminated (no combustion engine) | Cast iron usage down 80% |
| Transmission housing | Cast iron / aluminum | Single-speed reducer aluminum housing | Cast iron usage down 70% |
| Battery pack | Not present | Aluminum / steel protective enclosures (new component) | New demand for aluminum, copper, specialty steel |
| Traction motor | Not equipped | Electrical steel laminations, aluminum housing | Rising demand for ultra-thin low-loss electrical steel |
| Exhaust system | 409 stainless tubing | Fully eliminated | Zero demand for exhaust stainless tube |
| Fuel tank | Coated stamped steel | Eliminated | Reduced deep drawing mild steel consumption |
| Main BIW structure | Over 80% steel | 50–70% steel, increased aluminum ratio | Growing HSS and aluminum extrusion volumes |
| Vehicle wiring | 12V low-voltage copper | 12V + 400 / 800V high voltage copper & aluminum busbars | Higher copper and conductive aluminum consumption |
| Production tooling | Stamping + standard HPDC dies | Additional large gigacasting molds | Higher uptake of ESR refined H13 hot work steel |
Frequently Asked Selection Questions
Q: Which Steel Grades Are Used For NEV Battery Crash Protection Structures?
A: 1500MPa 22MnB5 Hot-Stamped Steel Is The Primary Choice For Side And Bottom Battery Crash Guards. Lightweight Platforms Pair This With High-Strength 6082 Aluminum Extrusions To Balance Mass Reduction And Crashworthiness. Low-Cost Vehicle Lines Adopt Multi-Layer Welded DP780 Assemblies.
Q: Is Powder Metallurgy Hot Work Steel Mandatory For Gigacasting Dies?
A: No Mandatory Specification Exists. ESR H13 Delivers Stable Output For Low-To-Medium Volume Prototype Runs. Lines Running Over 100,000 Casting Shots Annually Can Upgrade To QRO90 Supreme To Extend Maintenance Intervals. PM Hot Work Steel Is Only Deployed As Localized Inserts For Extreme Wear Zones At Present.
Q: What electrical steel works best for 800V high-voltage traction motors?
A: 20W250 and 25W300 ultra-thin non-oriented electrical steel are preferred, delivering lower core loss at high frequencies and mild range gains of 5–10 km per charge. 30W360 can be specified for mid/low-speed motors below 12,000 RPM to balance material cost.
Q: Why Specify DLC-Coated DC53 For Aluminum Outer Panel Stamping Dies?
A: 6000-Series Aluminum Alloys Tend To Gall Heavily During Forming. DC53 Offers Better Toughness Than Standard D2. Paired With DLC Diamond-Like Carbon Coating, Aluminum Pickup Is Greatly Reduced, Maintaining Class A Surface Finish And Cutting Downtime For Mold Polishing.