1. Introduction
A360 aluminum alloy occupies a central role in modern high-pressure die casting, prized for its combination of fluidity, strength, and corrosion resistance.
By offering an optimal balance of mechanical performance and castability, A360 has become an industry standard for automotive, marine, and consumer-electronics components.
Consequently, engineers and material scientists must understand its composition, behavior during manufacturing, in-service characteristics, and overall economic value.
This article covers A360’s metallurgical foundation, physical properties, mechanical performance, corrosion behavior, die-casting considerations, post-processing requirements, and applications.
2. Alloy Composition of Aluminum Alloy A360
Aluminum alloy A360 is a high-pressure die-casting alloy designed to balance fluidity, mechanical strength, and corrosion resistance.
Its composition places it—chemically—near ADC12 (sometimes called A383 in North America) but with slightly higher magnesium to improve corrosion performance.
Below is the typical chemical breakdown (all values in weight percent):
| Element | Typical Composition (wt %) | Role/Effect |
|---|---|---|
| Aluminum (Al) | Balance (~90–93 %) | Primary matrix; provides lightweight structure and ductility |
| Silicon (Si) | 9.5 – 10.5 % | Enhances fluidity, lowers melting point, reduces shrinkage porosity |
| Magnesium (Mg) | 0.45 – 0.70 % | Improves corrosion resistance, participates in Mg₂Si precipitates for strength after aging |
| Copper (Cu) | 2.50 – 3.50 % | Solid-solution strengthening; enhances tensile/yield strength when aged |
| Zinc (Zn) | 2.00 – 3.00 % | Provides additional solid-solution strengthening; improves elevated‐temperature performance |
| Iron (Fe) | ≤ 1.30 % | Impurity that forms Fe-rich intermetallics; excessive Fe can reduce ductility and promote pitting |
| Manganese (Mn) | 0.35 – 1.00 % | Acts as a grain refiner, reduces coarse intermetallics, slightly enhances pitting resistance |
| Lithium (Li) | ≤ 0.07 % | (In some variants) Reduces density, marginally increases stiffness (not typical for standard A360) |
| Titanium (Ti) | ≤ 0.10 % | Grain refiner (via Ti-B master alloys), controls microstructure |
| Nickel (Ni) | ≤ 0.10 % | Controlled impurity; avoids embrittlement and hot cracking |
| Tin (Sn) | ≤ 0.10 % | Controlled impurity; excessive Sn can embrittle |
| Lead (Pb) | ≤ 0.10 % | Controlled impurity; minimized to avoid embrittlement |
3. Physical & Thermal Properties of A360 Aluminum Alloy
| Property | Value | Units | Notes |
|---|---|---|---|
| Density | 2.74 | g/cm³ | Approximately one-third the density of steel |
| Thermal Conductivity | 120 | W/m·K | Facilitates heat dissipation in heat sinks and housings |
| Coefficient of Thermal Expansion (CTE) | 21.5 | µm/m·°C | Roughly twice that of steel; important for dimensional design |
| Melting Range (Solidus–Liquidus) | 570 – 585 | °C | Narrow interval ensures good fluidity and controlled solidification |
| Fluidity (Tested in HPDC conditions) | 200 – 250 | mm (flow length) | Can fill a 1 mm section up to 200–250 mm under 70 MPa pressure |
| Specific Heat Capacity | 0.90 | J/g·°C | Requires moderate energy to raise temperature |
| Electrical Conductivity | 32 – 35 | % IACS | Comparable to other Al–Si–Mg casting alloys |
| Solidification Shrinkage | 1.2 – 1.4 | % | Low shrinkage aids dimensional accuracy in die-cast components |
4. Mechanical Properties of A360 Aluminum Alloy
| Property | As-Cast (T0) | T5 (Aged) | Units | Notes |
|---|---|---|---|---|
| Tensile Strength (σu) | 260 – 300 | 320 – 360 | MPa (37 – 44 ksi / 46 – 52 ksi) | Aging induces Mg₂Si precipitation, raising strength by ~20 %. |
| Yield Strength (0.2% σy) | 150 – 170 | 200 – 230 | MPa (22 – 25 ksi / 29 – 33 ksi) | Higher yield after T5 allows thinner sections under same load. |
| Elongation (%) | 2 – 4 | 4 – 6 | % | Ductility improves modestly with T5 aging as micro-precipitates refine dislocation motion. |
| Brinell Hardness (HBW) | 65 – 85 | 85 – 100 | HB | Hardness increase reflects fine Mg₂Si dispersion; benefits wear resistance in machined parts. |
| Fatigue Endurance Limit | ~100 | ~110 | MPa | Endurance at 10⁷ cycles under rotating bending; T5 yields slight improvement. |
| Creep Rate (50 MPa @ 100 °C) | ~1 %/10³ h | ~0.8 %/10³ h | % strain in 10³ h | Creep becomes significant above 100 °C; T5 marginally lowers creep rate. |
5. Corrosion Resistance & Surface Behavior
Native Passive Film (Al₂O₃)
Pure aluminum and its alloys naturally form a thin (2–5 nm) amorphous Al₂O₃ layer within seconds of air exposure.
This adherent film self-heals when scratched, thereby preventing further oxidation.
In static, neutral pH conditions, bare A360 typically exhibits corrosion rates below 5 µm/year,
rendering it more durable than most uncoated steels.
Pitting & Crevice Corrosion
In chloride-laden environments—such as seaside or deicing conditions—pitting corrosion can initiate where Cl⁻ ions breach the passive layer.
In ASTM B117 salt-spray tests, unprotected A360 samples often begin to show small pits after 200–300 hours at 5% NaCl, 35 °C.
By contrast, marine-grade 5083 performs beyond 1 000 hours. Thus, protective coatings or anodizing become mandatory for sustained marine exposure.
Similarly, crevice corrosion can develop under gaskets or shadowed areas, where localized acidification lowers the pH below 4, further destabilizing the oxide.
Design solutions include ensuring tight tolerances for proper drainage and using non-porous sealants.
Protective Treatments
- Anodizing (Type II and Type III): Sulfuric-acid anodizing builds oxide layers of 5–25 µm (Type II) or 15–50 µm (hard-anodize Type III).
Sealing with nickel acetate or polymer-based sealers imparts additional protection, extending salt-spray resistance to over 500 hours without pit initiation. - Conversion Coatings: Chromate conversion (Iridite) and non-chromate alternatives (e.g., zirconium-based) create a thin,
<1 µm barrier that both primes the surface and inhibits initial corrosion. - Organic Coatings: Epoxy primers combined with polyurethane or fluoropolymer topcoats achieve
over 1 000 hours in salt-spray testing, provided surface prep (caustic etch and deoxidizing) is strictly followed.
Galvanic Interactions
Aluminum’s position in the galvanic series makes it anodic to many structural metals—copper, stainless steel, and even titanium.
In a humid or wet electrolyte, galvanic couples can drive A360 corrosion at a rate of 10–20 µm/year when in direct contact with copper. To mitigate galvanic action, best practices include:
- Isolation: Nylon or polyamide washers between aluminum and steel fasteners.
- Coatings: Applying a protective layer on at least one of the metals.
- Design: Avoiding dissimilar-metal stacks or ensuring minimal electrolyte entrapment.
6. Die-Casting Characteristics of A360 Aluminum Alloy
When it comes to high-pressure die casting (HPDC), A360 aluminum stands out due to its exceptional fluidity, solidification behavior, and overall castability.
Filling Behavior and Fluidity
First and foremost, the high silicon content of A360 imparts a low melting temperature and a broad semi-solid interval,
translating into outstanding fluidity under typical HPDC parameters (liquidus at ~585 °C, solidus at ~570 °C). As a result:
- Thin-Wall Capability: In standard die-casting trials, A360 can fill wall thicknesses as low as 1.0 mm along a straight flow length of 200–250 mm when injected at 70–90 MPa and plunger speeds of 1.5–2.0 m/s.
- Reduced Cold-Shut Risk: The alloy’s low viscosity under pressure minimizes premature freeze-off, decreasing cold-shut defects by over 30 % compared to lower-Si alloys like A380.
Furthermore, because A360’s solidification range is relatively narrow, mold designers can define runners and gates that promote uniform flow.
For example, a 0.5 mm increase in gate cross-section (from 5 mm² to 5.5 mm²) often yields 10 % faster fill times, reducing the likelihood of laps or misruns.
Shrinkage and Solidification Control
Next, A360’s nominal shrinkage rate of 1.2–1.4 % on solidification requires careful die design to prevent shrink-age porosity. To counteract this:
- Directional Solidification: Strategic placement of chills—copper inserts or beryllium-copper sleeves—at thick sections locally accelerates cooling.
In practice, adding a 2 mm thick copper chill adjacent to a 10 mm base reduces the local solidification time by 15–20 %, directing feed metal toward high-risk regions. - Sequential Feeding: Employing multiple, staged gates can allow molten A360 to feed thick bosses last, ensuring that these areas remain liquid until final solidification.
Simulation data often shows that a two-gate design reduces shrink-void volume by 40 % relative to a single-gate layout. - Vacuum-Assist Techniques: Drawing a vacuum of 0.05 MPa beneath the shot sleeve decreases entrapped air, permitting denser feed metal.
Trials demonstrate that vacuum HPDC lowers porosity from ~3 % to less than 1 % by volume, improving tensile strength by 10 MPa on average.
Porosity Mitigation and Quality Assurance
Although A360’s rapid heat extraction promotes fine microstructures, it can also generate gas and shrinkage porosity if not controlled. Common mitigation strategies include:
- Gas-Flush Nozzles: By introducing an inert gas pocket behind the shot piston, gas-flush systems mobilize and expel dissolved hydrogen from the melt.
In A360 pilot runs, gas-flush reduced hydrogen content from 0.15 mL/100 g Al to 0.05 mL/100 g Al, cutting gas-porosity by over 60 %. - Plunger Acceleration Profiles: A steeper acceleration ramp (e.g., 0.5 m/s² to 2.0 m/s² within the first 15 mm) improves turbulence-controlled filling, minimizing stagnant zones that trap air.
Data show that this profile change alone can lower pore counts in critical tension areas by 20 %. - Die Temperature Management: Maintaining die temperatures between 200 °C and 250 °C ensures that the surface does not freeze too rapidly.
Thermocouple monitoring in key die zones can keep temperature fluctuations within ±5 °C, reducing surface-freeze defects responsible for surface porosity.
Quality assurance further relies on automated X-ray radiography or CT scanning to detect pores ≥ 0.5 mm.
For mission-critical automotive parts, an allowable pore volume of < 0.3 % is often set; contemporary metrology techniques report over 95 % detection rates for such criteria.
Tooling Wear and Maintenance
While A360’s silicon content (9.5–10.5 %) enhances fluidity, those hard Si-particles also accelerate die wear. Consequently:
- Tool Steel Selection: High-quality H13 or H11 alloys are standard, but coating them with TiN or Diamond-Like Carbon (DLC) reduces friction.
In production, TiN coatings have extended mold life by 25–30 %, from an average of 150 000 shots to over 200 000 shots before requiring refurbishment. - Die Surface Finishing: Polishing die cavities to Ra < 0.2 µm minimizes adhesion of solidifying aluminum, reducing soldering and galling.
Polished dies also require fewer ejection pins and less spray lubricant—cutting maintenance time by 10–15 %. - Preventive Maintenance Intervals: Based on cumulative fill cycles and X-ray feedback, foundries often implement die servicing every 50 000–75 000 shots.
This schedule typically involves re-polishing, re-coating, and inspecting for micro-cracks using fluorescent penetrant methods.
7. Machinability & Post-Processing
Machining Characteristics
A360’s 9.5–10.5% silicon content yields a combination of moderate hardness and brittle silicon phases. Consequently:
- Tooling: Use carbide tooling (grades K20–P30) with sharp geometries and positive rake angles to manage chip control.
- Cutting Parameters: Speeds of 250–400 m/min, feed rates of 0.05–0.2 mm/rev, and moderate depth of cut (1–3 mm) deliver optimal balance between tool life and surface finish.
- Coolant: Flood cooling with water-based emulsions or synthetic coolants is recommended to remove heat and lubricate the tool–workpiece interface.
-
Motor end cover aluminum alloy A360 die-castings
Drilling, Tapping, and Thread-Forming
- Drilling: Utilize peck-drilling (retracting every 0.5–1.0 mm) to evacuate chips and avoid built-up edge.
- Tapping: Employ spiral-flute taps for through-holes; select base hole sizes per ISO 261 (e.g., #10–24 tap uses a 0.191 in. pre-drill).
- Thread-Forming: In softer A360 sections (T0), thread rolling can produce stronger threads than cutting but requires precise pilot holes.
Joining Methods
- Welding: A360’s high heat input can exacerbate porosity; thus, Gas Tungsten Arc Welding (GTAW) with filler rod 4043 (Al–5Si) or 5356 (Al–5Mg) is preferred.
Preheating to 100–150 °C can reduce thermal gradients but is not always necessary. - Brazing and Soldering: A360 joints are commonly brazed using aluminum brazing rods containing 4–8% silicon.
Flux selection is critical—zinc-based fluxes can dissolve the passive film and ensure wetting.
8. Applications & Industry Examples
Automotive Sector
A360 dominates applications requiring lightweight, complex geometries with moderate mechanical loads. Examples include:
- Transmission Housings: Replacing ductile iron, A360 housings weigh 30–40% less while delivering comparable static strength (≥ 300 MPa tensile).
- Engine Brackets and Mounts: Die-cast A360 brackets can reduce part count by integrating bushings and mounts,
lowering total assembly weight by 1.5 kg per vehicle. - Case Study: A major OEM replaced a gray-iron transmission tail housing (weighing 4.5 kg) with an A360 die-cast unit (3.0 kg),
saving 1.5 kg and cutting production costs by 12% due to shorter cycle times and reduced machining.
Marine & Marine Components
Marine-grade A360, when anodized, resists corrosion in saltwater environments:
- Boat Hardware: Hinges, cleats, and trim pieces manufactured in A360 sustain 200 hours in ASTM B117 salt-spray testing without visible pitting.
- Submerged Pump Casings: A360 pumps for bilge and livewell applications can operate at 5 m depth for over 5 years with routine anodizing maintenance every 2 years.
Consumer Electronics & Enclosures
A360’s combination of thermal conductivity and form accuracy suits heat sinks and housings:
- LED Lamp Housings: The alloy’s thermal conductivity (120 W/m·K) helps dissipate up to 20 W per housing, preventing LED lumen depreciation.
- Telecom Racks and Enclosures: EMI-shielded A360 extrusions achieve 50 dB attenuation at 1 GHz, while remaining cosmetically attractive after anodizing.
Industrial & HVAC
- Compressor Housings: In HVAC systems, A360 housings operate continuously at 100 °C and sustain 5000 hours of cyclic temperature changes between –20 °C and 100 °C with less than 0.2% creep.
- Heat Exchanger End Caps: A360’s dimensional accuracy (± 0.1 mm in thin walls) allows leak-free sealing with O-rings in condensers and evaporators.
9. Comparison to Other Die-Casting Alloys
When specifying a Die-casting alloy, A360 often competes with several well-established materials—most notably A380 (ADC10), ADC12 (A383), A413, A356, and LM6.
Each alloy offers distinct advantages in terms of fluidity, mechanical strength, corrosion resistance, and cost.
| Alloy | As-Cast Tensile (MPa) | T5/T6 Tensile (MPa) | Fluidity (1 mm, mm) | Corrosion Resistance | Die Wear | Primary Applications |
|---|---|---|---|---|---|---|
| A360 | 260–300 | 320–360 (T5) | 200–250 | Very good (with anodize) | High (10–15 %) | Marine pumps, automotive brackets |
| A380 | 240–280 | 300–340 (T5) | 180–200 | Moderate (requires coating) | Moderate (8–12 %) | General-purpose housings |
| ADC12 | 250–300 | 300–340 (T5) | 220–240 | Good (with anodize) | Moderate (10–12 %) | Automotive brackets, enclosures |
| A413 | 230–260 | 280–320 (T5) | 240–260 | Good (low Cu) | Very high (12–15 %) | Hydraulic cylinders, fuel system parts |
| A356 | 200–240 | 310–340 (T6) | 180–200 | Very good (low Cu) | Lower (6–8 %) | Aerospace castings, HVAC components |
| LM6 | 220–260 | 300–340 (T6) | 260–280 | Excellent (minimal Cu) | Very high (12–15 %) | Marine fittings, architectural parts |
10. Emerging Trends & Future Directions
Advanced Alloy Variants
- Nanoparticle-Reinforced A360: Incorporation of SiC or TiB₂ nanoparticles aims to enhance wear resistance and reduce thermal expansion.
Preliminary studies show up to 15% improvement in hardness without sacrificing fluidity. - Low-Copper A360 Variants: By reducing Cu to < 1.5%, next-generation alloys maintain age-hardening capability while further improving corrosion resistance, particularly for coastal infrastructure.
Additive Manufacturing Synergies
- Hybrid Die-Cast/3D-Printed Tools: Additive manufacturing of conformal cooling channels in die inserts reduces cycle times by 10–15% and yields more consistent microstructures in A360 castings.
- Direct Metal Deposition (DMD) Repairs: Using A360 powder, DMD restores worn HPDC dies, extending die life by 20–30% and lowering tooling costs.
Digital Manufacturing & Industry 4.0
- Real-Time Process Monitoring: Embedding thermocouples and pressure sensors in dies,
combined with AI algorithms, predicts porosity hotspots, thus reducing scrap by 5–8%. - Predictive Maintenance: Machine-learning models correlate die temperature profiles with wear patterns, scheduling maintenance only when necessary, improving uptime by 12%.
11. Conclusions
Aluminum alloy A360 stands out in die casting for its excellent fluidity, balanced mechanical properties, and improved corrosion resistance compared to some other die-casting alloys.
While not ideal for extreme marine immersion without additional protection,
it excels in automotive, industrial, and consumer applications requiring thin walls, moderate strength, and dimensional precision.
Proper heat treatment, surface finishing, and design for manufacturability ensure that A360 delivers reliable, long-lasting performance.
At LangHe, we stand ready to partner with you in leveraging these advanced techniques to optimize your component designs, material selections, and production workflows.
ensuring that your next project exceeds every performance and sustainability benchmark.
FAQs
What is A360 aluminum alloy?
A360 is a high-pressure die-casting alloy characterized by approximately 9.5–10.5 % silicon, 0.45–0.70 % magnesium, 2.5–3.5 % copper, and 2–3 % zinc.
It balances exceptional fluidity with good corrosion resistance and strength, making it ideal for thin-wall, complex die-cast components.
What heat treatment does A360 require?
- Solution Treatment (Optional): 525–535 °C for 4–6 h, then water quench.
- T5 Artificial Aging: 160–180 °C for 4–6 h. This causes Mg₂Si precipitates to form, raising tensile strength by ~15–20 % and hardness by ~20 HB.
Over-aging (exceeding 6 h or 180 °C) can coarsen precipitates and reduce strength.
What are A360’s typical processing yields and lifecycle costs?
- HPDC Yield: Net-shape yields of 90–95 %; scrap after trimming 5–10 %. Vac-assist and optimized gating can reduce scrap to < 3 %.
- Lifecycle Cost: Anodized A360 outperforms painted steel for outdoor parts: maintenance every 3–5 years (anodize) vs. annual repaint (steel).
Recycled A360 scrap value $1.50–$2.00/kg versus steel at $0.15/kg.
