Aluminum A383: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

A383 is a die-casting aluminum alloy belonging to the Al–Si–Cu family of casting alloys rather than the wrought 1xxx–7xxx series. It is best described as an Al–Si hypoeutectic casting alloy with significant copper additions intended to raise strength and hardenability after heat treatment. Major alloying elements are silicon for castability and fluidity, copper for strength and response to aging, and small amounts of Fe, Mn and Mg which influence intermetallic formation, strength and porosity control. The strengthening mechanisms are primarily precipitation hardening (when solution-treated and artificially aged) combined with the fine distribution of Si-rich phases from rapid solidification in die-casting processes.

Key traits of A383 include a balance of moderate-to-high static strength, good dimensional accuracy and pressure-tightness in die-cast parts, and acceptable corrosion resistance in atmospheric environments. The alloy welds reasonably well with attention to filler selection and pre/post-heat controls, and it exhibits fair machinability in the as-cast state due to a predictable microstructure. Typical industries using A383 are automotive (structural housings, pump bodies), consumer products (electrical housings), and industrial equipment where complex thin-walled castings with moderate strength are required. Engineers select A383 when a combination of die-cast producibility, improved post-cast strength via heat treatment, and cost-effective material usage is needed compared with higher-cost wrought alloys or more corrosion-resistant but less castable alternatives.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High	Excellent	Excellent	Soft, annealed-like condition; rarely used for final die-cast parts but useful for stress relief and rework.
F (as-cast)	Moderate	Low–Moderate	Good	Good	Standard as-cast die-cast condition; microstructure reflects casting solidification.
T5	Moderate–High	Low	Fair	Good	Cooled from elevated temperature and artificially aged; common for die-cast components to gain strength.
T6	High	Low	Poor–Fair	Good	Solution heat-treated, quenched and artificially aged; delivers highest strength and hardness achievable for A383.
T7	Moderate	Low–Moderate	Fair	Good	Overaged condition to improve dimensional stability and resistance to stress relaxation at elevated temperature.

Temper has a major effect on mechanical performance because the Al–Si–Cu system responds to solution treatment and artificial aging with precipitation of Cu-rich phases. As-cast (F) delivers good dimensional detail and surface finish but limited peak strength, while T5/T6 raise tensile and yield through precipitate hardening at the cost of some ductility. Selecting a temper is a trade-off between as-cast producibility, final strength targets, and post-casting processing cost; heat-treated tempers require strict control of solution temperatures, quench severity, and aging cycles to achieve consistent properties.

Chemical Composition

Element	% Range	Notes
Si	8.0 – 11.0	Primary strengthening and fluidity agent; controls eutectic fraction and shrinkage behavior.
Fe	0.6 – 1.6	Impurity that forms Fe-rich intermetallics; high levels reduce ductility and increase hot-tearing tendency.
Mn	0.1 – 0.5	Scavenges Fe to form less detrimental intermetallics, improves strength modestly.
Mg	0.05 – 0.40	Contributes to precipitation hardening (Mg2Si) when present; typical low for A383.
Cu	1.6 – 3.0	Principal age-hardening element; increases strength but can reduce corrosion resistance.
Zn	0.05 – 0.5	Minor strengthening and residual element; limited effect at low levels.
Cr	0.05 – 0.25	Controls grain structure and improves recrystallization resistance, reduces hot-tearing.
Ti	0.02 – 0.15	Grain refiner; added in small amounts to refine primary aluminum grains.
Others (including Ni, Pb, Sn)	≤ 0.15 each; balance Al	Trace elements kept low; total impurities controlled to maintain castability and mechanical performance.

The chemistry is tuned to achieve castability, control shrinkage and porosity, and allow precipitation hardening with Cu as the principal age-forming element. Silicon governs fluidity and the morphology of the eutectic which strongly affects elongation and fatigue life. Copper raises achievable yield and tensile strength after heat treatment but is a trade-off against general corrosion resistance, so sealing and coatings may be required for aggressive environments.

Mechanical Properties

A383 exhibits typical die-cast tensile behavior where as-cast specimens show moderate ultimate tensile strength and limited ductility due to eutectic silicon and intermetallics. Solution heat treatment followed by artificial aging (T6) significantly raises both yield and tensile strength through precipitation of Cu-rich phases while often reducing elongation. Hardness follows the same trend, with Brinell or Vickers values increasing substantially after aging due to a finer precipitate distribution and reduced solid-solution softening.

Fatigue performance is strongly tied to casting quality: porosity, inclusions and surface defects dominate life. Thinner sections cool faster, refining microstructure and improving strength but also increasing the risk of cold shuts or misruns if gating is not optimized. Designers must account for notch sensitivity and often apply shot peening, surface machining, or local heat treatments to improve fatigue resistance in cyclic-load components.

Property	O/Annealed	Key Temper (e.g., T6)	Notes
Tensile Strength (MPa)	160 – 240	260 – 360	Wide range depends on section thickness, porosity and exact chemistry; T6 delivers peak values.
Yield Strength (0.2% proof, MPa)	70 – 140	160 – 260	Yield rises markedly with aging; design should use conservatively measured values from representative castings.
Elongation (%)	3 – 12	1.5 – 6	Elongation falls with strength; thin sections and T6 often at the low end of the range.
Hardness (HB)	50 – 90	80 – 130	Hardness correlates with strength and is useful for quick QC of heat treatment consistency.

Physical Properties

Property	Value	Notes
Density	2.70 g/cm³	Typical aluminum alloy density; useful for mass estimates of castings.
Melting Range	~577 – 640 °C	Eutectic Si lowers liquidus; die-casting solidification behaviors depend on alloy and cooling rate.
Thermal Conductivity	~100 – 150 W/m·K	Lower than pure Al due to alloying and Si-rich phases; still good for general heat-sinking.
Electrical Conductivity	~25 – 40 %IACS	Reduced from pure aluminum by alloying, especially Cu and Si.
Specific Heat	~880 – 900 J/kg·K	Typical for Al alloys; relevant for thermal cycling and quench calculations.
Thermal Expansion	~21 – 24 µm/m·K	Relatively high thermal expansion compared with steels; important for joined structures and mating parts.

These physical properties control thermal processing, casting solidification and service performance. The moderate thermal conductivity and specific heat govern rapid heat extraction in die-casting, influencing microstructure gradients in wall thickness transitions. Thermal expansion and matching to mating materials must be accommodated when designing assemblies to avoid thermal stresses and leakage.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	Not typical	N/A	N/A	A383 is not routinely produced as rolled sheet; limited feasibility via secondary processes.
Plate	Not typical	N/A	N/A	Thick plate is rarely produced; castings replace plate-based fabrication for complex geometries.
Extrusion	Not typical	N/A	N/A	Alloy chemistry and cast-focused processing make extrusions uncommon for A383.
Tube	Limited (cast tubular shapes)	Moderate	F, T5	Specialty cast tubes or sleeves can be produced but machining is often required.
Bar/Rod	Limited (cast billets)	Moderate	F, T6	Cast bars or billet-fed machining are possible but less economical than dedicated wrought alloys.
Die-cast parts	Thin-wall down to ~1–2 mm	Dependent on temper and section	F, T5, T6	Primary and intended product form; complex geometry and high dimensional fidelity.

A383 is optimized for high-pressure die-casting where thin walls, complex cores and high production rates are prioritized. Wrought forms are rare because the composition and microstructure are tuned for casting behavior rather than rolling or extrusion. Processing differences—such as gating design, die filling speed, and cooling control—strongly influence local mechanical properties, and typical downstream operations include machining, heat treatment, and surface finishing.

Equivalent Grades

Standard	Grade	Region	Notes
AA	A383	USA	Aluminum Association casting designation used for specification and purchasing.
EN	EN AC‑(AlSiCu series) (approx.)	Europe	No single direct one-to-one AW wrought equivalent; look for EN AC alloys in the AlSi9Cu/AlSi10Cu family as functional equivalents.
JIS	ADC12 (approx.)	Japan	ADC12 is a widely used Japanese die-casting alloy with similar Al–Si–Cu chemistry and comparable casting behavior.
GB/T	AlSi9Cu or ZL104 (approx.)	China	Chinese casting grades in the AlSi9Cu family are commonly used as practical equivalents; exact chemistry and property tolerances differ.

Equivalency between standards is approximate because cast alloy families are specified by chemistry ranges, casting processes and end-use properties rather than identical designations. Users should verify tensile, hardness and heat-treatment response for the exact specification batch, as small differences in Cu, Mg and Fe dramatically change age-hardening response and corrosion behavior. Always request certified material test reports and, where necessary, perform trial pours to confirm dimensional and mechanical performance under intended die-casting parameters.

Corrosion Resistance

A383 demonstrates good general atmospheric corrosion resistance typical of Al–Si casting alloys because of the protective alumina surface film that reforms rapidly after exposure. In industrial or mildly corrosive environments the alloy performs well, especially when surfaces are sealed, painted or anodized; however, copper additions reduce resistance relative to purer Al–Si alloys, increasing susceptibility to localized attack. In marine or chloride-laden environments, A383 is vulnerable to pitting and crevice corrosion particularly on machined surfaces or where coatings are damaged; corrosion inhibitors, sacrificial anodes, and protective coatings are common mitigation strategies.

Stress corrosion cracking (SCC) is not a dominant failure mode for A383 under typical service temperatures and stress levels, but care must be taken in high-tensile, aged conditions where residual stresses and corrosive media combine. Galvanic interactions with dissimilar metals must be considered: when coupled to steel or copper, anodic behavior will accelerate aluminum attack unless insulated or protected. Compared with 5xxx magnesium-bearing alloys, A383 has lower general corrosion resistance; compared with 6xxx wrought alloys (anodizable), A383 is less amenable to high-quality anodizing and therefore often requires organic coatings for long-term protection.

Fabrication Properties

Weldability

A383 can be welded using common fusion methods such as MIG and TIG, but die-cast microstructures and porosity present challenges to obtaining defect-free joints. Pre-heating and controlled heat input reduce cracking tendencies, and filler alloys based on 4043 (Al–Si) or 5356 (Al–Mg) are typically used depending on service requirements; 4043 tends to produce better fluidity and lower cracking in Si-rich castings. Welded zones can experience HAZ softening and altered corrosion behavior, so design to avoid high-load-bearing welds or post-weld heat treatment is recommended.

Machinability

As-cast A383 machines reasonably well due to a relatively stable eutectic morphology and the presence of brittle Si particles that aid chip breaking. Machinability indices are often quoted as fair to good compared to 6061; carbide tooling with positive rake and moderate cutting speeds provides the best balance between tool life and surface finish. Chips are typically short and granular; feed rates and coolant must be optimized to avoid built-up edge and to control surface quality for sealing surfaces.

Formability

A383's formability is limited compared with wrought aluminum sheet because cast microstructure lacks the ductility and strain-hardening capacity of rolled alloys. Bending and forging of cast parts are possible in annealed or heavily machined conditions but typically cause cracking in thin sections or at stress concentrators. Best practice is to design cast features into part geometry rather than attempt post-cast forming; when forming is required, use softer tempers (O/F) and carry out thermal or mechanical stress-relief operations.

Heat Treatment Behavior

A383 is a heat-treatable casting alloy owing to its copper content, and it responds to the standard solution-treatment and artificial aging sequence used for Al–Si–Cu systems. Solution treatment is typically performed at temperatures in the 495–540 °C range to dissolve soluble Cu and Si-bearing phases, with hold times adjusted for section thickness to avoid incipient melting. Quenching must be rapid to retain solute in supersaturated solid solution; die-cast components often require specialized quench routing to avoid distortion and to minimize retained porosity.

Artificial aging for T5/T6 is performed at roughly 150–200 °C for several hours to precipitate fine Cu- and Mg-bearing intermetallics that raise yield and tensile strength. T5 (direct aging after quench from casting) provides moderate hardening without the full solution-treatment step, while T6 (solution-treated then aged) delivers maximum strength. Overaging to T7 reduces peak strength but improves dimensional stability and high-temperature softening resistance, useful for components exposed to service temperatures or thermal cycling. For non-heat-treatable conditions, controlled work hardening and stress-relief anneals are the available mechanisms to adjust properties.

High-Temperature Performance

A383 exhibits a loss of yield and tensile strength with increasing temperature, with significant softening typically observed above 150 °C and pronounced strength reduction above 200–250 °C. The precipitation-hardened state is especially temperature-sensitive; prolonged exposure to moderately elevated temperatures can lead to overaging and permanent reduction of peak properties. Oxidation is minimal at these temperatures due to protective alumina formation, but at high service temperatures coincident with corrosive environments, protective coatings may degrade and localized corrosion can accelerate.

The heat-affected zones of welded or reworked components can show additional vulnerability under high-temperature service due to coarsening of precipitates or dissolution of strengthening phases. For applications requiring sustained elevated-temperature strength, consider alternative alloys specifically designed for high-temperature service or provide engineering controls such as thermal breaks and cooling strategies.

Applications

Industry	Example Component	Why A383 Is Used
Automotive	Valve bodies, pump housings, transmission covers	Good castability for thin-walled complex geometries and improved strength after aging.
Marine	Pump housings, fittings	Castability and moderate corrosion resistance; economical for non-structural marine fittings with coatings.
Aerospace	Small housings, brackets, tooling components	Dimensional accuracy and ability to produce complex shapes with reasonable strength and weight savings.
Electronics	Enclosures, heat-sink housings	Thermal conductivity and die-cast dimensional control enable integrated thermal-management parts.

A383 is selected for components where complex geometry and thin walls are necessary, and where the ability to age-harden assembled castings provides a distinct manufacturing advantage over wrought fabrication. Its combination of die-cast productivity, subsequent heat-treatment capability, and balanced mechanical properties makes it a cost-effective choice for medium-duty structural and enclosure applications.

Selection Insights

A383 is a strong candidate when die-cast manufacturability and the option for age-hardening are primary selection drivers. Compared with commercially pure aluminum (1100), A383 trades higher strength and better casting behavior for reduced electrical conductivity and lower room-temperature formability. Compared with work-hardened alloys such as 3003 or 5052, A383 generally offers higher achievable tensile and yield strengths after heat treatment but slightly lower general corrosion resistance and less cold-forming capability. Compared with common heat-treatable wrought alloys like 6061 or 6063, A383 provides superior near-net-shape, thin-walled cast capability and lower cost for complex parts, even though peak strength and fatigue performance may be lower in some geometries.

Choose A383 when part geometry or production cost dictates die-casting, when post-cast heat treatment is feasible, and when moderate corrosion protection (coatings or anodizing where appropriate) meets service needs. For highly corrosive or critically fatigue-loaded applications, evaluate higher-performance