Aluminum A413.0: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

A413.0 is positioned in the aluminum 4xxx family, a silicon-based series that emphasizes weldability and casting/forging fluidity rather than the highest peak temper strengths. The alloy is formulated with silicon as the primary alloying element augmented by controlled additions of magnesium and copper to enable precipitation hardening and improved mechanical performance. Strengthening in A413.0 is principally achieved through a combination of solution treatment followed by artificial aging (precipitation hardening), with limited work-hardening response available for cold-formed components. Typical traits include moderate-to-high strength in heat-treated tempers, good corrosion resistance in many atmospheres, excellent weldability due to silicon, and adequate formability in softer tempers.

A413.0 is commonly encountered in automotive structural and body components, powertrain housings and brackets, marine fittings, and components requiring a balance of castability/extrudability and mechanical performance. The alloy is chosen where designers need an aluminum that accepts welding easily while still being capable of intermediate heat-treated strength levels — a practical compromise between 3xxx/5xxx non-heat-treatable alloys and higher-strength 6xxx/2xxx heat-treatable families. In manufacturing, A413.0’s silicon content improves surface finish and reduces hot-cracking tendencies during joining and casting, which simplifies fabrication and lowers scrap rates. For applications requiring a combination of good machinability, dimensional stability after heat treatment, and corrosion resistance without the expense or handling complexity of high-strength 2xxx or 7xxx alloys, A413.0 is frequently selected.

A413.0’s appeal comes from balanced metallurgical design: silicon provides low solidification range and weld filler compatibility, magnesium and copper provide precipitation-strength potential, and small transition elements (Ti, Cr) refine microstructure and control grain growth. The alloy demonstrates predictable aging kinetics and a relatively broad processing window for solutionizing and aging compared with high-strength alloys that are more sensitive to quench rates. This makes A413.0 attractive to OEMs and fabricators who value process robustness, repeatable mechanical properties, and lower rejection rates during welding and heat treatment. Its combination of moderate cost, availability, and manufacturing friendliness often tips the selection in favor of A413.0 for mid-performance structural applications.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High (18–25%)	Excellent	Excellent	Fully annealed condition for forming and joining
H14	Low–Moderate	Moderate (12–18%)	Good	Excellent	Light work-hardening; good for simple formed parts
T5	Moderate	Moderate (8–14%)	Fair	Excellent	Cooled from hot working and artificially aged for stress relief
T6	High	Low–Moderate (6–12%)	Reduced	Good	Solution-treated and peak-aged for maximum strength
T651	High	Low–Moderate (6–12%)	Reduced	Good	Solution-treated, stress-relieved by stretching, artificially aged

Temper has a strong influence on the balance between forming and final mechanical performance in A413.0. Soft O and light H tempers are used where extensive cold forming or deep drawing is required, while T5/T6/T651 tempers are used where strength and dimensional stability after heat treatment are primary concerns.

Transitioning between tempers alters fatigue resistance, residual stress levels, and susceptibility to springback; therefore designers must select the temper consistent with forming operations and the intended service loads. Welding performance is best in soft tempers, though T6 condition parts can be welded with appropriate filler and post-weld heat treatment to restore strength in the HAZ.

Chemical Composition

Element	% Range	Notes
Si	6.0–12.0	Principal alloying element; improves fluidity, lowers melting range, and enhances weldability
Fe	0.2–1.2	Impurity element that forms intermetallics; controlled to limit embrittlement
Mn	0.05–0.6	Grain structure modifier and strength contributor in some tempers
Mg	0.3–1.4	Provides precipitation strengthening (Mg2Si) when combined with Si
Cu	0.2–1.5	Enhances strength via precipitation but can reduce corrosion resistance if excessive
Zn	0.05–0.5	Minor; can marginally influence strength and corrosion behavior
Cr	0.05–0.3	Controls grain structure and limits recrystallization during thermal processing
Ti	0.02–0.2	Grain refiner for castings and extrusions; improves mechanical reliability
Others (including Al remainder)	Balance	Trace additions (B, Zr) may be specified for special processing control

The chemistry targets a silicon-dominant matrix with sufficient magnesium and copper to allow predictable age hardening via Mg–Si and Cu-containing precipitates. Silicon lowers the alloy’s solidus temperature and reduces shape-change on solidification, which benefits casting and welding processes. Small amounts of transition elements such as Cr and Ti act as grain refiners and recrystallization inhibitors, improving toughness and dimensional stability after heat input.

Control of iron and other impurity elements is important because excessive Fe produces brittle intermetallics that reduce ductility and fatigue life. Balancing Mg and Si is critical to ensure the correct volume fraction and composition of strengthening precipitates, while Cu additions improve strength but require corrosion mitigation strategies in marine or high-chloride environments.

Mechanical Properties

A413.0 in annealed condition exhibits relatively low yield and tensile strengths with high ductility, enabling deep drawing and complex forming operations without cracking. In heat-treated conditions (T5/T6/T651), the alloy develops significantly higher yield and ultimate strengths through the formation of fine precipitates, at the expense of elongation and reduced bendability. Fatigue performance is highly process-sensitive; specimens from T6 tempers show improved crack-initiation resistance under high static loads, but the presence of casting or machining defects and coarse intermetallics can dominate crack propagation behavior.

Thickness and product form strongly influence mechanical response because cooling rates during quenching affect precipitate dispersion and HAZ softening in welded components. Thin sections can be fully strengthened with T6 aging, while thick sections may exhibit gradients in mechanical properties due to slower cooling and differences in microstructural coarsening. Hardness correlates well with tensile properties in A413.0; Rockwell or Brinell hardness measurements are commonly used as a production control for confirming temper and aging response.

Property	O/Annealed	Key Temper (T6/T651)	Notes
Tensile Strength	120–170 MPa	280–360 MPa	T6 offers up to ~2.5× increase vs O; range depends on exact composition and thickness
Yield Strength	60–100 MPa	220–300 MPa	Yield approaches tensile in overaged conditions; design should use conservative yield values
Elongation	18–25%	6–12%	Ductility drops with increasing age-hardening and Si-rich intermetallics
Hardness	40–60 HB	90–130 HB	Hardness correlates with aging response; used for QC of temper condition

Physical Properties

Property	Value	Notes
Density	2.68–2.74 g/cm³	Slightly alloy-dependent; near-aluminum baseline
Melting Range	Solidus ≈ 555–575 °C; Liquidus ≈ 615–645 °C	Si lowers the solidus relative to pure Al; casting/welding windows affected
Thermal Conductivity	100–140 W/m·K	Lower than pure Al but still high compared with steels; affected by Si and alloying
Electrical Conductivity	28–42 % IACS	Reduced from pure Al due to solutes and precipitates
Specific Heat	0.85–0.92 J/g·K	Similar to other Al alloys; useful for thermal management calculations
Thermal Expansion	22–24 µm/m·K (20–100 °C)	Typical for Al alloys; design for differential expansion in bimetallic assemblies

A413.0 retains the favorable low density and high thermal conductivity typical of aluminum, making it an attractive choice where weight savings and heat dissipation are required. The silicon content reduces electrical and thermal conductivity relative to pure aluminum but not to the extent that it precludes use in heat-sinking applications for moderate-power electronics. The melting range and reduced solidus temperature demand careful welding and casting parameter control to avoid hot tearing and to manage HAZ effects.

Thermal expansion is significant compared with steels or composites, so assemblies combining different materials require allowances for differential thermal movement. The combination of specific heat and conductivity supports transient thermal design analysis for parts exposed to pulsed heat loads.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.5–6.0 mm	Uniform thickness allows reliable T6 strengthening	O, H14, T5, T6	Used where surface finish and formability are needed
Plate	6–100 mm	Thick sections may be underaged due to quench limitations	O, T5, T6	Requires control of cooling to avoid core soft zones
Extrusion	1–100 mm profiles	Good longitudinal strength and controlled grain flow	O, T5, T6	Ti and Cr additions aid in hot-range extrusion stability
Tube	1–20 mm wall	Behavior similar to sheet/extrusion; welding joints feasible	O, T5, T6	Used in structural, hydraulic, and marine tubing
Bar/Rod	Ø3–200 mm	Rods can be drawn and aged; section size impacts quench	O, T6	Used for machined components and fasteners in some cases

Sheet and plate are commonly rolled and receive subsequent solution and aging treatments to reach target tempers, while extrusions benefit from silicon’s improved flow to produce thin webs and intricate cross-sections. Tube and bar production must consider the interaction between cross-sectional size and quench rates; large cross sections often require special quench techniques or interrupted aging to produce evenly distributed mechanical properties. Machining stock (bars/rods) is frequently supplied in soft tempers and hardened after rough shaping to reduce tool wear and distortion.

Forming operations are most economical in O or lightly work-hardened states; final heat treatment is used to set mechanical properties when dimensional stability is critical. Welded assemblies may be designed to minimize post-weld distortion and to allow for local or global heat-treatment restoration of properties.

Equivalent Grades

Standard	Grade	Region	Notes
AA	A413.0	USA	Aluminum Association designation used in North American specifications
EN AW	No direct equivalent	Europe	No single EN AW code maps exactly; EN AW-4032 or EN AW-4047 are close analogs depending on Si/Mg/Cu balance
JIS	No direct equivalent	Japan	Similar cast/extrusion alloys exist but exact composition varies across manufacturers
GB/T	No direct equivalent	China	Comparable domestic alloys may be used; careful property verification required

There is no single universally identical international counterpart to A413.0, because regional standards often split silicon-based alloys into several more narrowly defined grades. European and Asian standards offer alloys with similar Si and Mg contents (e.g., 4032 family or modified 4047 variants) that approximate A413.0’s balance of weldability and heat-treatable strength, but differences in Cu, Ti, and trace elements produce measurable differences in aging kinetics and corrosion resistance. When substituting, engineers should compare actual composition ranges, heat-treatment response curves, and certified mechanical properties rather than relying on nominal grade names.

Cross-referencing should be done using certified material test reports and comparative mechanical testing for critical components, particularly when fatigue life, fracture toughness, or corrosion resistance are design drivers. Where regulatory certification or aerospace approval is required, use of the exact specified grade or validated equivalent is mandatory.

Corrosion Resistance

A413.0 exhibits generally good atmospheric corrosion resistance similar to many Al–Si alloys, benefiting from the passive aluminum oxide layer and silicon’s modest impact on electrochemical stability. In marine or chloride-rich environments the alloy performs acceptably but is more susceptible to localized pitting than high-magnesium 5xxx alloys; protective coatings or anodizing are commonly applied for long-term service. Stress corrosion cracking (SCC) susceptibility is low to moderate depending on temper; T6 conditions with residual tensile stresses and aggressive environments merit caution and may require post-weld heat treatment or design changes to mitigate SCC risk.

Galvanic interactions follow standard aluminum behavior; when mated to more noble metals (stainless steel, copper alloys), A413.0 will corrode preferentially unless electrically insulated or sacrificial measures are provided. Compared with 5xxx (Al–Mg) alloys, A413.0 trades slightly reduced resistance to crevice and pitting corrosion for improved weldability and heat-treatable strength. When compared to 6xxx-series alloys, A413.0 can have comparable atmospheric corrosion performance but may be more tolerant of welding without filler mismatch due to silicon’s favorable effect on solidification.

Surface treatments such as anodizing, chromate conversion, and organic coatings extend service life dramatically and are routine for marine and exterior applications. Designers should assess local alloy chemistry and temper, as small differences in Cu and Mg content materially influence corrosion performance in aggressive environments.

Fabrication Properties

Weldability

A413.0 welds well with standard TIG and MIG processes owing to silicon’s beneficial effect on reducing hot-cracking and promoting fluid weld pools. Recommended filler alloys include ER4043 (Al–Si) for general-purpose welds and ER5356 (Al–Mg) where higher joint strength is required and base alloy compatibility is acceptable. Hot-cracking risk is low compared with many 6xxx and 2xxx alloys, but attention to joint fit-up, purge, and control of heat input is still necessary to minimize porosity and oxide inclusion.

Post-weld heat-affected zones (HAZ) may experience softening if the base metal was in a peak-aged condition; in such cases local re-solutionizing or artificial aging can be used to recover properties if geometry and production economics permit. Preheat is rarely required but interpass temperature control and stress-relief techniques may be applied for large weldments to control distortion.

Machinability

Machinability of A413.0 is moderate and generally better than high-strength 2xxx alloys due to silicon’s abrasive but chip-breaking effects; cutting tools should be selected for abrasive wear resistance, typically carbide or coated carbide inserts. Recommended machining practices include high feed rates with moderate cutting speeds to promote chip segmentation and control tool temperature; coolant use is advisable to flush trapped chips and reduce thermal loads. Surface finish and tool life depend heavily on Si particle size and distribution; fine, uniformly distributed Si leads to better finishes and less tool wear.

For tight tolerance components, roughing in softer tempers followed by a final age hardening and finish machining pass can reduce distortion and improve dimensional control. Threading, tapping, and deep-hole drilling require appropriate lubrication and often reduced penetration rates to avoid work-hardening or tool breakage.

Formability

Formability is excellent in O and H14 tempers, allowing deep draws and complex bends with relatively small internal radii compared with T6 conditions. Typical minimum bend radii in annealed sheet are in the range of 0.5–1.0× thickness for simple bends, increasing for T6-aged conditions and complex geometries. Cold work increases strength but reduces ductility; where heavy forming is required, form in the annealed condition and then apply final heat treatment to restore or increase strength.

Springback in T6 condition is more pronounced and must be accounted for in die design and validation. Where stretch forming or severe cold working is necessary, lubrication and progressive forming steps reduce the risk of cracking at Si-rich intermetallic sites.

Heat Treatment Behavior

Solution treatment for A413.0 is typically carried out at temperatures in the 510–540 °C range to dissolve Mg- and Cu-bearing phases into a supersaturated aluminum matrix. Rapid quenching to room temperature is required to retain the solute in solid solution; quench rate control is critical for thick sections to avoid coarse precipitate formation and reduced age response. Artificial aging is performed at 150–190 °C for T5/T6 responses, with peak hardness and strength achieved after controlled time at temperature depending on exact composition.

Overaging reduces strength but improves toughness and stress-corrosion resistance, and may be selected intentionally for components requiring a balance of properties. The T651 temper adds a controlled stretch or stress-relief operation after solutionizing to minimize residual stresses and distortion, improving dimensional stability for machined parts. A413.0 displays reasonably broad aging windows compared with more quench-sensitive 2xxx alloys, making process control less critical but still important for repeatable performance.

For non-heat-treatable processing or where heat treatment is impractical, work hardening via cold forming offers incremental strengthening but cannot reach the peak levels available through precipitation hardening. Annealing cycles are used to