Aluminum 356.0 vs A356.0 (Sand cast, T6)

Aluminum 356.0 vs. A356.0 in Sand Cast, T6 Condition: A Comparison Table

Below is a comprehensive comparison of Aluminum 356.0 and A356.0 in the T6 condition (solution heat-treated and artificially aged). This format makes it easy to identify differences in key designations, chemical composition, mechanical properties, and more.

1. Designation and Standards

Property	356.0	A356.0
Designation	356.0 (Aluminum Association)	A356.0 (Aluminum Association)
UNS Number	A03560	A13560
EN Number	EN AC-42000 / EN AC-Al Si7Mg	EN AC-42000 / EN AC-Al Si7Mg
Aluminum 356.0 vs A356.0 (Sand cast, T6)

2. Chemical Composition

Element	356.0 (wt%)	A356.0 (wt%)	Effect of Difference
Aluminum (Al)	90.1–93.3	91.1–93.2	Higher aluminum in A356.0 improves homogeneity.
Silicon (Si)	6.5–7.5	6.5–7.5	Identical silicon levels enhance wear resistance and castability.
Magnesium (Mg)	0.2–0.45	0.25–0.45	Higher minimum Mg in A356.0 improves strength.
Iron (Fe)	≤0.6	≤0.2	Lower Fe in A356.0 reduces brittle intermetallic phases.
Copper (Cu)	≤0.25	≤0.2	Lower Cu in A356.0 enhances corrosion resistance.
Manganese (Mn)	≤0.35	≤0.1	Tighter Mn control in A356.0 improves ductility.
Zinc (Zn)	≤0.35	≤0.1	Reduced Zn improves stability in A356.0.
Titanium (Ti)	≤0.25	≤0.2	Comparable grain refinement in both alloys.
Aluminum 356.0 vs A356.0 (Sand cast, T6)

3. Mechanical Properties

Property	356.0	A356.0	Impact
Yield Strength (MPa)	146–162	197–213	A356.0 demonstrates significantly higher yield strength.
Tensile Strength (MPa)	205–226	245–264	Higher tensile strength in A356.0 makes it suitable for dynamic loading.
Elongation (% strain)	2.1–2.5	3.7–4.4	Better ductility in A356.0 supports more demanding applications.
Hardness (Vickers, HV)	83–91	87–97	A356.0 offers slightly higher hardness.
Fatigue Strength (MPa)	53.1–64.9	100–116	A356.0 vastly outperforms 356.0 in fatigue resistance.
Fracture Toughness (MPa·m⁰·⁵)	19–21	35–40	Higher fracture toughness in A356.0 resists crack propagation.
Aluminum 356.0 vs A356.0 (Sand cast, T6)

4. Thermal Properties

Property	356.0	A356.0	Effect
Melting Point (°C)	582–648	560–610	A356.0 melts slightly earlier, aiding castability.
Thermal Conductivity (W/m·°C)	150–162	149–155	Comparable performance in heat dissipation.
Thermal Shock Resistance (°C)	91.6–105	123–138	A356.0 offers better resistance to rapid temperature changes.
Aluminum 356.0 vs A356.0 (Sand cast, T6)

5. Applications

Application Type	356.0	A356.0
Automotive	Wheels, structural parts	Suspension components, housings
Aerospace	Non-critical castings	Fatigue-critical structural castings
Marine	General-purpose hardware	Corrosion-resistant fittings
Industrial	Pump housings, tools	Fatigue-resistant industrial parts
Aluminum 356.0 vs A356.0 (Sand cast, T6)

Key Takeaways

Mechanical Advantage: A356.0 offers superior yield strength, tensile strength, and fatigue resistance, making it suitable for applications with dynamic or cyclic loading.
Casting Quality: Lower impurity levels in A356.0 result in reduced defects, improving performance consistency.
Corrosion Resistance: Tighter control of Fe and Cu in A356.0 ensures better resistance to environmental degradation.
Applications: While both alloys are versatile, A356.0 is better suited for critical applications requiring high strength and fatigue resistance.

Aluminum 356.0 vs. A356.0 in Sand Cast, T6 Condition: T6 Heat Treatment Effects

The T6 heat treatment, which includes solution heat treatment and artificial aging, dramatically transforms the mechanical properties and microstructure of both Aluminum 356.0 and A356.0. This process enhances the strength, hardness, and fatigue resistance, while also influencing intermetallic phases and alloy performance.

T6 Heat Treatment Process

Solution Heat Treatment:
- Dissolves Mg2Si and other soluble phases into the aluminum matrix.
- Homogenizes the microstructure and reduces segregation.
- Typical temperatures: ~530–550°C, held for several hours.
Quenching:
- Rapid cooling to trap dissolved elements in a supersaturated solution.
- Creates the basis for aging hardening.
Artificial Aging:
- Controlled heating (~155–175°C) to precipitate Mg2Si particles.
- Precipitation strengthens the alloy by impeding dislocation motion.

Effects of T6 Heat Treatment on Microstructure

Precipitation of Mg2Si:
- Mg2Si particles form uniformly in A356.0 and 356.0 during aging.
- These fine precipitates contribute to enhanced tensile and yield strength.
Reduction of Intermetallic Phases:
- Heat treatment reduces detrimental phases like β-Al5FeSi in A356.0, particularly due to lower Fe content.
- In 356.0, some Fe-rich phases persist but are minimized.
Grain Refinement:
- Heat treatment improves grain uniformity, particularly in A356.0 due to stricter impurity controls.

Chemical Composition During T6 Heat Treatment

Element	356.0	A356.0	T6 Impact
Magnesium (Mg)	Reacts with Si to form Mg2Si	Reacts with Si to form Mg2Si	Both alloys gain strength through Mg2Si precipitation.
Silicon (Si)	Forms Mg2Si and refines grain size	Forms Mg2Si and refines grain size	Critical for precipitation hardening.
Iron (Fe)	Persistent as Al-Fe phases	Reduced Al-Fe phases	Lower Fe in A356.0 improves ductility and reduces brittleness.
Copper (Cu)	Limited effect at low levels	Limited effect at low levels	Minimal Cu in both alloys ensures high corrosion resistance.
Aluminum 356.0 vs A356.0 (Sand cast, T6)

Mechanical Properties After T6 Heat Treatment

Property	356.0 (T6)	A356.0 (T6)	Reason for Differences
Yield Strength (MPa)	146–162	197–213	A356.0 benefits more from T6 due to reduced intermetallic phases.
Tensile Strength (MPa)	205–226	245–264	Enhanced Mg2Si precipitation boosts A356.0 strength further.
Elongation (% strain)	2.1–2.5	3.7–4.4	Tighter impurity control in A356.0 ensures better ductility.
Hardness (Vickers, HV)	83–91	87–97	Both alloys harden due to Mg2Si precipitation, but A356.0 excels.
Fatigue Strength (MPa)	53.1–64.9	100–116	A356.0’s fine microstructure results in superior fatigue performance.
Aluminum 356.0 vs A356.0 (Sand cast, T6)

Why Does 356.0 Have More Strength in F Condition But A356.0 Outperforms in T6?

F Condition:
- In the as-fabricated state, 356.0 has higher strength due to the presence of Fe-rich intermetallic phases (e.g., β-Al5FeSi), which act as hard but brittle inclusions.
- A356.0 has fewer impurities, leading to slightly lower strength in the F condition but better ductility.
T6 Condition:
- T6 heat treatment neutralizes the disadvantage of lower Fe content in A356.0 by precipitating Mg2Si phases, which dominate strength improvement.
- Reduced intermetallics in A356.0 improve toughness and fatigue resistance compared to 356.0.

Comparison of Microstructure Changes

Feature	356.0	A356.0	T6 Effect
Intermetallic Phases	Persistent Al-Fe-Si	Minimized Al-Fe-Si	T6 reduces β-Al5FeSi in both, more effectively in A356.0.
Grain Structure	Coarser grains with impurities	Finer, more uniform grains	Aging promotes uniform precipitation in both alloys.
Precipitate Formation	Mg2Si uniformly distributed	Mg2Si uniformly distributed	Mg2Si precipitation strengthens both, with better control in A356.0.
Ductility	Lower due to residual intermetallics	Higher due to fewer intermetallics	A356.0 exhibits better post-T6 elongation.
Aluminum 356.0 vs A356.0 (Sand cast, T6)

Key Takeaways

T6 Enhancements: Both alloys benefit significantly from Mg2Si precipitation during T6 treatment, with A356.0 achieving superior performance due to stricter impurity control.
Strength Trade-offs: While 356.0 offers higher strength in the F condition due to residual intermetallics, these phases hinder its performance post-T6.
Applications:
- 356.0: Suitable for non-critical components where initial strength is prioritized.
- A356.0: Ideal for dynamic, cyclic, and high-stress environments requiring enhanced fatigue resistance.

This detailed explanation ties the T6 process to microstructural and property differences, emphasizing how A356.0’s tighter controls maximize its performance advantage.