4032 Aluminum

Representative aluminum raw/semi-finished material photo; exact grade not verified

4032 Aluminum (AA 4032, UNS A94032) is a heat-treatable wrought 4xxx aluminum–silicon alloy developed for forged and machined components exposed to friction, heat cycling, and tight-clearance service. Its 11.0–13.5% silicon content gives it substantially lower thermal expansion and better wear behavior than general-purpose wrought aluminum alloys. Copper, magnesium, and nickel provide a useful response to solution treatment and artificial aging. The alloy is especially associated with forged pistons, compressor components, and precision moving parts where dimensional stability at operating temperature is as important as room-temperature strength.

Chemical Composition (wt.%)
Chemical Composition wt.%
Element	Min	Max
Silicon	11.0	13.5
Iron	—	1.0
Copper	0.50	1.3
Magnesium	0.8	1.3
Chromium	—	0.10
Nickel	0.50	1.3
Zinc	—	0.25
Others, each	—	0.05
Others, total	—	0.15
Aluminum	Remainder

Composition notes

Silicon: Registered composition limit.
Iron: Registered maximum.
Copper: Registered composition limit.
Magnesium: Registered composition limit.
Chromium: Registered maximum.
Nickel: Registered composition limit.
Zinc: Registered maximum.
Others, each: Registered maximum for each unspecified element.
Others, total: Registered total maximum for unspecified elements.
Aluminum: Registered balance.

Registered wrought-alloy composition limits, percent by weight. Blank fields in the Aluminum Association registered table are not reported as zero and are omitted here. “Others” limits apply to unspecified elements.

Values below are source-reported nominal or typical values, not minimum design allowables. Mechanical and thermal values are reported for 4032-T6 at room temperature where stated; actual properties vary with product form, section size, forging practice, and heat treatment.

Use the button to switch between Metric and US Customary units.

Table of 4032 Aluminum Properties

Table of 4032 Aluminum Properties
Physical Properties	Metric
Density	2.68 g/cm³2.68 g/cm³
Mechanical Properties	Metric
Ultimate Tensile Strength (T6)	~380 MPa
Yield Strength, 0.2% Offset (T6)	~315 MPa
Elongation at Break (T6)	~9 %
Thermal Properties	Metric
Thermal Conductivity (T6)	~150 W/m·K
Coefficient of Thermal Expansion	19.4 µm/m·K
Melting Range	530–570 °C

Test conditions & data notes

Density: Calculated nominal density for active wrought alloy 4032.
Ultimate Tensile Strength (T6): Typical T6 temper; room temperature.
Yield Strength, 0.2% Offset (T6): Typical T6 temper; room temperature.
Elongation at Break (T6): Typical T6 temper.
Thermal Conductivity (T6): Typical T6 temper.
Coefficient of Thermal Expansion: Reported typical value.
Melting Range: Reported solidus-to-liquidus range.

Material Conditions & Tempers

4032 is supplied primarily as wrought bar, rod, billet, forging stock, and finished forgings. T6 is a common condition for strength, wear resistance, and dimensional stability. Temper availability and guaranteed properties must be confirmed against the applicable product specification and producer certification.

Condition	Tensile Strength	Yield / Proof Strength	Notes
F			As fabricated; properties depend on the specific working process and are not controlled to a heat-treated temper level. Often relevant to forging stock or material awaiting final heat treatment.
O			Annealed condition used where maximum softness or forming capability is needed before final machining or heat treatment. High silicon content still limits ductility relative to lower-silicon wrought alloys.
T6	~380 MPa typical	~315 MPa typical	Solution heat treated and artificially aged. This is the common service condition for forged pistons and wear-sensitive machined components. Typical values listed on this page are not specification minimums.
T651			Solution heat treated, stress relieved by controlled stretching, and artificially aged. May be specified for suitable wrought forms when improved residual-stress control is required; confirm product-form availability.

Advantages & Limitations

Advantages	Limitations
High silicon content provides low thermal expansion, helping maintain running clearance during repeated heating and cooling. Silicon-rich microstructure supports good scuffing and abrasion resistance in piston, compressor, and sliding-contact service. Copper and magnesium permit precipitation hardening, while nickel supports strength retention at moderately elevated temperatures. Wrought and forged product routes offer soundness and directional integrity suitable for highly loaded precision components. Generally machines well after heat treatment, making it practical for close-tolerance piston skirts, ring grooves, and rotating parts.	High silicon reduces ductility and toughness compared with lower-silicon forged alloys; sharp geometry and severe forming require care. Fusion welding is generally avoided for critical 4032 components because high silicon content and heat-treatment effects can impair weld-joint performance. Copper-bearing chemistry gives only moderate corrosion resistance; use suitable coatings, lubrication, or environmental protection for exposed service. Mechanical properties are strongly dependent on temper, forging reduction, section thickness, and heat-treatment control. It is not a general structural sheet alloy and is commonly sourced in bar, billet, and forged forms rather than broad sheet applications.

Advantages

Limitations

High silicon content provides low thermal expansion, helping maintain running clearance during repeated heating and cooling.
Silicon-rich microstructure supports good scuffing and abrasion resistance in piston, compressor, and sliding-contact service.
Copper and magnesium permit precipitation hardening, while nickel supports strength retention at moderately elevated temperatures.
Wrought and forged product routes offer soundness and directional integrity suitable for highly loaded precision components.
Generally machines well after heat treatment, making it practical for close-tolerance piston skirts, ring grooves, and rotating parts.

High silicon reduces ductility and toughness compared with lower-silicon forged alloys; sharp geometry and severe forming require care.
Fusion welding is generally avoided for critical 4032 components because high silicon content and heat-treatment effects can impair weld-joint performance.
Copper-bearing chemistry gives only moderate corrosion resistance; use suitable coatings, lubrication, or environmental protection for exposed service.
Mechanical properties are strongly dependent on temper, forging reduction, section thickness, and heat-treatment control.
It is not a general structural sheet alloy and is commonly sourced in bar, billet, and forged forms rather than broad sheet applications.

Processing & Fabrication

Process	Description
Forging	4032 is commonly converted from wrought billet into piston blanks and other near-net shapes. Use controlled deformation and die design because the high-silicon alloy has less hot-work tolerance than more ductile aluminum alloys.
Heat treatment	For T6-type service, solution heat treat, quench, and artificially age using a qualified cycle for the actual product form. Control distortion and quench response carefully, particularly for thin piston sections and tight-tolerance forgings.
Machining	Machine after final or near-final heat treatment when dimensional stability and wear-resistant surfaces are required. Sharp cutting tools, rigid fixturing, and effective chip control are beneficial because silicon particles are abrasive.
Welding and joining	Avoid fusion welding for critical load-bearing or precision parts unless a procedure is specifically qualified. Mechanical fastening, shrink fits, or other engineered joining methods are often more appropriate.
Surface finishing	Use lubrication-compatible coatings or surface treatments where scuffing, corrosion exposure, or break-in behavior requires additional protection. Verify compatibility with the engine or compressor environment.

Applications

4032 is selected where a lightweight forged aluminum component must retain controlled dimensions and resist rubbing or scuffing as temperature rises. Its most characteristic use is the forged piston, but the same high-silicon, heat-treatable chemistry is valuable in other precision, sliding, and rotating components.

Forged internal-combustion-engine pistons: Low thermal expansion helps control piston-to-cylinder clearance, while high silicon improves skirt and ring-groove wear behavior.
Compressor pistons and rotating components: The alloy combines low mass, heat-treatment response, and dimensional stability during cyclic thermal loading.
Bushings and wear-sensitive precision parts: Silicon-rich microstructure provides improved resistance to abrasion and sliding wear compared with lower-silicon wrought aluminum alloys.
Valve-train and high-temperature machined components: Copper, magnesium, and nickel additions support useful strength and stability in moderately elevated-temperature service.
Precision forged blanks: Forged stock provides a practical route to near-net, low-mass parts that need extensive finish machining and tight geometry control.

Standards & Designations

Designation	Value	Description
Aluminum Association	4032	Active registered wrought aluminum-alloy designation; the registered chemical composition is published by the Aluminum Association.
UNS	A94032	Common Unified Numbering System designation associated with aluminum alloy 4032.
AA designation	AA 4032	Alternate designation format used for this wrought aluminum alloy.

Frequently Asked Questions

Why is 4032 aluminum widely used for forged pistons?

Its high 11.0–13.5% silicon level reduces thermal expansion and improves wear behavior, so forged piston clearances can be controlled more closely during engine heat cycles. The Cu–Mg–Ni additions also allow useful heat-treated strength.

What is the practical difference between 4032 and a general-purpose alloy such as 6061?

4032 contains far more silicon and is tailored for low expansion, wear resistance, and piston-type service. Compared with 6061, it is less ductile and less suitable as a general welded structural alloy, but is better suited to close-clearance hot moving parts.

Can 4032 aluminum be welded?

It is not normally chosen for welded fabrication, especially when joint strength, fatigue performance, or dimensional control are critical. High silicon content and the loss of heat-treatment strength in the heat-affected zone make qualified alternative joining methods preferable.

References & Data Notes

(n.d.). Aluminum Association — International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys, December 2025. https://www.aluminum.org/sites/default/files/2026-01/Teal%20Sheets%20December%202025.pdf
(n.d.). 4032 Aluminum Alloy: Composition, Properties and Applications. https://premiumalu.com/mastering-4032-aluminum-essential-guide
(n.d.). 4032 Aluminum | Al 4032 Alloy Properties, Composition, Machining and Comparison. https://metalnpi.com/aluminum/4032-aluminum-al-4032-alloy-properties-composition-machining-and-comparison

Chemical limits are registered Aluminum Association values. Nominal density is from the Aluminum Association calculated-density table. Other numerical properties are typical source-reported values and should not replace the governing drawing, material specification, or mill/forging certification.