Which Rivet is Used for Riveting Magnesium Alloy Structures?

Magnesium alloys are highly favored in aerospace, automotive, and other industries for their lightweight properties and high strength-to-weight ratio. However, their high chemical reactivity poses a significant challenge: galvanic corrosion when in contact with dissimilar metals. This necessitates rivets that not only ensure mechanical compatibility (e.g., matching strength and ductility) but also minimize electrochemical potential differences to prevent corrosion. Ideal rivets for magnesium alloys should possess low electrical potential, moderate hardness, and excellent fatigue resistance to maintain structural integrity over time.

2. Primary Rivet Types and Their Applications

2.1 Pure Aluminum Rivets: Basic Corrosion-Resistant Choice

Pure aluminum rivets (e.g., 1100 series) are a common choice due to their close electrical potential to magnesium alloys (-0.85V vs. -1.66V for magnesium), significantly reducing galvanic corrosion risks. With low hardness (HB≤30), they are gentle on magnesium surfaces during installation, making them suitable for non-load-bearing applications such as interior panel connections, trim piece fastening, and lightweight assembly parts.Typical Uses: Riveting magnesium alloy dashboard brackets in automotive manufacturing and cabin interior components in aerospace.

2.2 Aluminum-Magnesium Alloy Rivets: High-Strength Lightweight Solution

5xxx series aluminum-magnesium alloys (e.g., 5056, 5052) offer a balance of corrosion resistance and mechanical strength (tensile strength up to 290 MPa). Their 3–5% magnesium content enhances compatibility with magnesium substrates, making them ideal for medium-load structures. Applications include drone magnesium alloy frames, automotive seat skeletons, and structural components requiring both durability and light weight.Process Note: Anodizing the rivet holes before installation creates an insulating oxide layer, further isolating dissimilar metals and improving joint reliability.

2.3 Titanium Alloy Rivets: High-Reliability Load-Bearing Connections

For critical aerospace and high-safety applications, titanium alloy rivets (e.g., TA1, TA2) are preferred. Although titanium’s electrical potential (-0.34V) is higher than magnesium, its naturally forming titanium dioxide (TiO₂) oxide layer acts as an effective insulator, blocking galvanic corrosion. With tensile strengths ranging from 300–500 MPa, they are suitable for load-bearing joints such as magnesium alloy wing skins bonded to frames.Considerations: Due to their high hardness, hydraulic riveting equipment is required to avoid substrate damage. Their higher cost limits use to essential components.

2.4 Plated Steel Rivets: Cost-Effective Composite Solution

Low-carbon steel rivets (e.g., 1008 steel) with zinc plating (thickness ≥8μm) provide an economical option. Zinc’s electrical potential (-0.76V) acts as a sacrificial layer, protecting magnesium alloys from corrosion. These rivets are suitable for temporary or non-exposed structures, such as magnesium alloy packaging reinforcement and fixture connections.Limitations: In humid environments, the zinc coating may wear over time, requiring sealants to prevent corrosion penetration.

3. Rivet Selection and Process Optimization

3.1 Priority on Electrical Potential Matching

Select rivet materials with a potential difference (ΔE ≤0.3V) relative to magnesium alloys. Aluminum-based rivets (pure aluminum/aluminum-magnesium) are preferred, followed by titanium and plated steel. Salt spray testing (ASTM B117) is recommended to verify corrosion rates, with no visible white rust after 72 hours as a standard.

3.2 Load-Based Selection Strategy

3.3 Environmental Adaptation Design

In marine or high-humidity environments, cadmium-plated titanium rivets (cadmium thickness 12–15μm) are recommended, as their self-sealing oxide layer reduces corrosion rates to below 0.001mm/year. For fuel-exposed areas, phenolic resin coatings add an extra layer of chemical protection.

Choosing the right rivet is crucial for reliable magnesium alloy structure connections. Engineers must balance mechanical loads, environmental conditions, and costs, combining material compatibility, process optimization, and protective designs to leverage magnesium’s lightweight advantages while ensuring safety. As rivetless technologies (e.g., electromagnetic riveting, self-piercing riveting) advance, magnesium alloy joining processes will continue to evolve toward higher efficiency and sustainability.