Aluminum Alloy Bolts in New Energy Vehicle Battery Packs

Aluminum Alloy Bolts in New Energy Vehicle Battery Packs: Engineering Application and ISO/DIN Fastening Solution

Lightweight Fastening Strategy for EV Battery Structural Systems

With the rapid expansion of the electric vehicle industry—global EV production and sales increased by 18% in Q1 2026—battery pack structural design has become a critical engineering focus.

Modern battery systems widely adopt full aluminum alloy enclosures, typically using 6xxx and 7xxx series aluminum alloys, which raises a key engineering question:

Should battery pack fastening systems use aluminum alloy bolts or traditional steel fasteners?

This article provides a technical application guide based on ISO 898-1 / ISO 16047 / DIN fastening engineering principles, analyzing when and how to use aluminum alloy bolts for EV battery pack systems.

1. Why Battery Packs Are Naturally Suitable for Aluminum Alloy Fasteners

1.1 Material Compatibility Advantage

Battery housings made from 6xxx / 7xxx aluminum alloys naturally align with:

• Aluminum alloy bolts

• Aluminum structural fasteners

• Lightweight threaded connection systems

This material consistency helps:

• Reduce galvanic corrosion risk

• Improve thermal expansion compatibility

• Enhance long-term joint stability

 1.2 Lightweight Engineering Benefit

Compared with steel fasteners:

• Aluminum alloy bolts weigh ~70% less

• Steel fasteners dominate mass in large EV battery packs      (hundreds of fastening points)

Even small per-bolt weight reduction leads to:

Significant overall vehicle range improvement through system-level mass reduction

 1.3 Common Application Zones in Battery Packs

Aluminum alloy bolts for EV battery pack fastening systems are typically used in:

• Battery module interconnect brackets

• Battery tray and cover plate fastening points

• Auxiliary high-voltage connector fixation systems

These areas share common characteristics:

• Medium load conditions

• High vibration exposure

• High weight sensitivity

• Assembly efficiency requirements

 2. Material Systems: Aluminum Alloy Bolt Performance Range

2.1 6xxx Series Aluminum Fasteners

• Tensile strength: ~300–400 MPa

• Excellent corrosion resistance

• Good formability

Suitable for:

• Non-structural fastening

• Auxiliary battery pack components

 2.2 7xxx Series High-Strength Aluminum Fasteners

• Tensile strength: ~480–550 MPa

• Improved strength-to-weight ratio

• Higher structural capability

Suitable for:

• Battery structural connection points

• Semi-load-bearing EV applications

Engineering Comparison

High-strength steel bolts (ISO 898-1 Grade 10.9 / 12.9):

• 1000 MPa tensile strength

• Suitable for high-load structural joints

 Conclusion:

Aluminum alloy bolts are not a full replacement, but a targeted lightweight engineering solution

 3. Key Technical Challenges in EV Battery Applications

3.1 Strength Limitation

Aluminum alloy bolts have inherent mechanical limits:

• Lower tensile strength than steel

• Not suitable for high-clamping-force joints

• Require precise load distribution design

 3.2 High-Temperature Creep and Preload Relaxation

EV battery packs can experience:

• Fast charging thermal spikes

• 60°C–80°C sustained operation

• Occasional peaks above 100°C

This leads to:

• Preload loss

• Joint relaxation

• Potential sealing failure

Engineering Mitigation

Advanced solutions include:

• Rare-earth modified aluminum alloys

• Optimized heat treatment processes

• High-temperature stabilized fastener designs (up to ~150°C      stable operation in advanced grades)

 3.3 Electrochemical Corrosion Risk

Battery packs are multi-material systems:

• Aluminum housings

• Copper busbars

• Zinc-coated steel brackets

• Mixed alloy interfaces

Electrochemical Principle

Aluminum potential:

• ~ -1.66 V (highly anodic)

Steel potential:

• ~ -0.44 V

This creates strong galvanic corrosion driving force.

 Risk Scenarios

• Galvanic corrosion (dissimilar metals)

• Crevice corrosion in confined joints

• Accelerated anodic degradation of aluminum bolts

 4. Corrosion Protection Strategies for Aluminum Alloy Bolts

4.1 Surface Treatment Engineering

Anodizing Treatment

• Forms dense Al₂O₃ oxide layer

• Improves corrosion resistance

• Widely used in EV structures

 Micro-Arc Oxidation (MAO)

• Produces ceramic-like oxide coating

• Higher hardness and wear resistance

• Suitable for high-performance battery systems

 4.2 Electrical Isolation Design

Using:

• Insulating washers

• Non-conductive coatings

• Polymer isolation sleeves

Function:

• Break the electrochemical current path

• Prevent galvanic corrosion loops

 4.3 Sacrificial Protection Systems

In severe environments:

• Zinc or magnesium sacrificial elements

• Controlled corrosion pathway design

• Protection of primary aluminum fasteners

5. Engineering Design Guidelines for EV Battery Fastening Systems

For ISO / DIN-based EV battery structural fastening design, engineers should follow:

5.1 Load Zoning Strategy

• High-load zones → steel bolts (ISO 898-1 10.9/12.9)

• Medium-load zones → 7xxx aluminum bolts

• Light-load zones → 6xxx aluminum bolts

5.2 Thermal Stability Validation

Fasteners must be validated under:

• Thermal cycling (-40°C to +85°C typical EV range)

• Fast charge thermal spikes

• Long-term creep resistance testing

5.3 Corrosion Compatibility Mapping

Each joint should evaluate:

• Material pairing compatibility

• Electrolyte exposure risk

• Protective coating requirements

 6. Application Outlook in New Energy Vehicles

Aluminum alloy bolts are rapidly expanding in:

• EV battery structural systems

• Lightweight chassis integration

• High-voltage electrical modules

• Next-generation modular battery architectures

Future development trends include:

• Hybrid aluminum–composite fastener systems

• Nano-ceramic coated aluminum bolts

• Smart preload monitoring fastening systems

 7. Engineering Fastener Solutions Provider

Guangzhou Juxin Development Co., Ltd. provides advanced fastening solutions for EV battery systems, including:

• ISO / DIN standard structural fasteners

• Lightweight aluminum alloy bolt systems

• High-strength steel battery pack bolts (ISO 898-1 Grade 10.9 /      12.9)

• Surface-engineered corrosion-resistant fastening solutions

• Customized EV battery pack fastening systems

Our engineering focus is:

Lightweight optimization + electrochemical protection + ISO/DIN reliability compliance

 Conclusion: Aluminum Alloy Bolts Are a System-Level Lightweight Engineering Solution

In EV battery pack design, aluminum alloy bolts are not a universal replacement for steel fasteners—they are a precision-engineered lightweight fastening solution for optimized zones.

Key engineering insights:

• Material compatibility improves system stability

• Strength limitation defines application boundaries

• Thermal and corrosion effects are critical design factors

• Proper surface engineering is essential for long-term      reliability

In modern EV architecture, successful fastening design is no longer about choosing one material over another, but about:

Designing a multi-material ISO/DIN-compliant fastening system with optimized performance distribution

Packaging Standard

At Juxin Fasteners, we apply standardized export packaging to ensure product protection, traceability, and compliance with international logistics requirements.

1. Standard Export Packaging

Unless otherwise specified, all products will be packed according to our factory standard export packaging, which includes:

Moisture-resistant inner protection

Poly bag or small box packing as required

Reinforced export cartons

Clear labeling with part number, specification, batch number, and quantity

Palletizing for sea or air shipment when necessary

Our standard packaging is designed to ensure safe transportation, efficient warehousing, and long-distance international shipping.

2. Customized Packaging Options

We also provide customized packaging solutions according to customer requirements, including but not limited to:

Private labeling

Customized barcodes

Specific carton dimensions

Retail packaging

Special pallet configuration

Customer-specific marking and identification

So that you know, customized packaging may involve additional costs and extended lead time depending on the complexity of the requirements.

3. Compliance & Quality Assurance

All packaging processes are controlled under our ISO 9001 quality management system to ensure consistency, traceability, and product integrity throughout the supply chain