Aluminum 6262: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

Alloy 6262 is a member of the 6xxx series aluminum alloys, which are aluminum–magnesium–silicon based and classified as heat‑treatable precipitation‑strengthened alloys. 6262 distinguishes itself from common 6xxx alloys by controlled additions of copper and small amounts of free‑machining constituents (such as lead, bismuth or tin) in many commercial variants to improve machinability while retaining the 6xxx family’s core behavior.

Strengthening in 6262 is primarily via solution heat treatment followed by quenching and artificial aging (precipitation hardening), producing Mg2Si and Mg‑Si‑Cu containing precipitates that raise yield and tensile strength. Key traits include moderate-to-high strength for a 6xxx alloy, good machinability (especially in leaded/bismuth modified variants), acceptable corrosion resistance, and reasonable formability and weldability compared with other heat‑treatable alloys.

Industries that commonly use 6262 include automotive and transportation (machined components and fittings), hydraulics and fluid power (valves, connectors), industrial machinery (shafts, housings) and some aerospace metallic hardware where machinability plus moderate strength is required. Designers choose 6262 when a balance of high machinability, heat‑treatable strength and acceptable corrosion performance is needed and when one wants a more easily machined alloy than standard 6061/6063 while still using a precipitation‑hardenable alloy.

6262 is often selected over free‑cutting 2xxx or 7xxx alloys when corrosion resistance and easier welding are required, and over 1xxx/3xxx/5xxx work‑hardened alloys when higher strength from heat treatment or better dimensional stability after aging is preferred. Its use is favored when post‑machining dimensional accuracy and surface finish are critical without sacrificing the benefits of a 6xxx precipitation system.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High	Excellent	Excellent	Fully annealed; best formability and ductility; softest condition.
H14	Low–Medium	Medium	Good	Good	Strain‑hardened or strain‑relieved; used for limited forming operations.
T5	Medium	Medium	Good	Good	Cooled from shaping and artificially aged; common for extrusions and parts requiring some strength.
T6	Medium–High	Medium–Low	Fair	Good	Solution heat treated and artificially aged; typical engineering temper for balance of strength and toughness.
T651	Medium–High	Medium–Low	Fair	Good	Solution heat treated, stress relieved by stretching, and artificially aged; improved dimensional stability for machining.
H32	Medium	Medium	Good	Good	Strain‑hardened and stabilized; used for formed parts needing stress relief.

Temper has a decisive influence on achievable mechanical performance and processing route. O and H‑series tempers favor forming and cold deformation, while T‑tempers (T5, T6, T651) are chosen when higher strength, hardness and dimensional stability after machining are required.

For machined components that require tight dimensional tolerance and higher strength, T651 is commonly preferred because the stretch‑stress relieving reduces distortion during subsequent machining and heat treatment cycles. Designers must balance formability (favoring O/H tempers) against final strength and fatigue performance (favoring T‑tempers).

Chemical Composition

Element	% Range	Notes
Si	0.6–1.0	Magnesium‑silicon matrix former; critical for precipitation hardening (Mg2Si).
Fe	0.35 max	Impurity element; higher levels reduce ductility and corrosion resistance.
Mn	0.05–0.40	Controls grain structure and can improve strength and corrosion resistance.
Mg	0.4–0.8	Strengthening element forming Mg2Si precipitates with Si.
Cu	0.2–0.8	Raises achievable strength and alters aging kinetics; moderate impact on corrosion resistance.
Zn	0.15 max	Minor; typically not a deliberate addition.
Cr	0.10 max	Grain‑refining and dispersoid former; improves toughness and resistance to recrystallization.
Ti	0.10 max	Grain refiner in castings and some wrought forms.
Others (Pb/Bi/Sn)	Trace, typically 0.01–0.35 each where present	Present in free‑machining variants to improve chip breaking and tool life; deleterious to welding if high.

The alloy composition is engineered to deliver a precipitation‑hardenable Mg‑Si base modified by modest copper additions to tune strength and aging behavior. Free‑machining elements (lead, bismuth, tin) are used in some commercial grades to improve chip control and surface finish during machining. Trace elements such as Cr and Mn act as dispersoid formers and grain refiners to stabilize microstructure during thermal processing.

The balance between Mg and Si is particularly important: it controls the volume fraction and distribution of Mg2Si precipitates and thus the peak achievable strength and response to aging. Copper alters both peak strength and corrosion characteristics and must be balanced against desired weldability and environment exposure.

Mechanical Properties

Tensile behavior of 6262 shows pronounced dependence on temper. In annealed (O) condition the alloy exhibits high elongation, low yield strength and relatively low tensile strength, making it suitable for forming operations. After solution treatment and artificial aging (T6/T651), the yield and tensile strengths increase significantly due to controlled precipitation of Mg2Si and Cu‑containing phases, but elongation decreases accordingly.

Yield and ultimate tensile strengths typically range from low values in the annealed state to moderate high values in peak aged conditions; yield strengths in T6/T651 are suitable for many structural and machined components. Hardness correlates with temper: annealed material is soft and measures low on Brinell or Vickers scales, while T6 treatments increase hardness substantially, improving wear and machining behavior under some conditions.

Fatigue performance of 6262 is influenced by surface finish, temper, and residual stress state; peak aged material shows higher fatigue limit for a given stress amplitude, but aluminum alloys do not exhibit a true fatigue endurance limit and fatigue life must be characterized for the expected loading range. Thickness affects mechanical behavior: thin sections tend to reach peak aging faster and may experience different quench response compared with thicker sections, necessitating control of heat‑treating schedules and quench rates for uniform properties.

Property	O/Annealed	Key Temper (e.g., T6/T651)	Notes
Tensile Strength	~110–160 MPa	~300–350 MPa	T6/T651 values depend on exact composition and aging schedule; mid‑range for 6xxx alloys.
Yield Strength	~40–90 MPa	~240–300 MPa	Yield increases dramatically after solution and age.
Elongation	~15–25%	~8–14%	Elongation reduces with increasing strength; fracture modes remain ductile.
Hardness (HB)	~35–60 HB	~85–120 HB	Hardness varies with temper and is commonly used to track aging response.

Physical Properties

Property	Value	Notes
Density	2.70 g/cm³	Typical for wrought aluminum alloys; beneficial strength‑to‑weight ratio.
Melting Range	~555–650 °C	Alloying shifts solidus/liquidus relative to pure Al (660 °C); consult spec for exact limits.
Thermal Conductivity	135–165 W/m·K	Lower than pure Al but still good for heat dissipation applications.
Electrical Conductivity	~24–34 %IACS	Reduced by alloying; lower than commercially pure aluminum.
Specific Heat	~0.90 J/g·K (900 J/kg·K)	Typical for aluminum alloys; useful for thermal inertia calculations.
Thermal Expansion	~23–24 µm/m·K (20–300 °C)	Typical coefficient for aluminum alloys; important for bolted/joined assemblies and sealing design.

6262 preserves the favorable physical property set of aluminum: low density, good thermal conductivity and favorable specific heat for many thermal management tasks. Thermal and electrical conductivities are lower than in high‑purity aluminum due to alloying elements, but the values remain adequate for many heat dissipation or conductor tasks where mechanical performance is also needed.

Designers must account for relatively high thermal expansion compared with steels: differential expansion in mixed‑material assemblies can drive stress at joints and fasteners. The melting and solidus ranges influence welding and brazing process windows and must be considered during thermal processing.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.4–6 mm	Homogeneous; thickness affects age response	O, H14, T5, T6	Used for stamped or machined panels and cosmetic components.
Plate	6–50+ mm	Thick sections require controlled quench for uniform T6	O, T6, T651	Heavy components and machined blocks; slower cooling can reduce peak properties.
Extrusion	Various cross‑sections	Good strength in T5/T6 after aging	T5, T6, T651	Complex profiles for structural and housing components.
Tube	OD varies, wall thickness variable	Strength scales with temper and wall thickness	O, T5, T6	Used for hydraulic sleeves, structural tubes, and machined tube parts.
Bar/Rod	Diameters 3–200 mm	Common for turned and machined parts	O, T6, T651	Preferred when turned to tight tolerances; free‑machining variants often used in bar form.

Processing differences arise from section thickness and cross‑section complexity: thin sheet ages differently and will reach target properties faster than thick plate. Extrusions require controlled cooling and solution/age schedules optimized for cross‑sectional thickness to avoid overaging or soft cores. Bar and rod forms of free‑machining 6262 are widely available for high‑volume turning operations where chip control and tool life are prioritized.

Applications differ by form: sheet and plate suit panels and stamped parts; extrusions enable integrated profiles and guide rails; bar/rod and tube are mainly used for machined fittings, shafts and hydraulic components. Selection of temper and pre‑treatment is pivotal to reduce distortion during subsequent machining.

Equivalent Grades

Standard	Grade	Region	Notes
AA	6262	USA	Aluminium Association designation; base reference for commercial specifications.
EN AW	6262	Europe	EN designation commonly mirrors AA numbering for this wrought alloy; check supplier certification.
JIS	—	Japan	No direct one‑to‑one JIS grade; 6262 is typically treated as a special alloy and compared functionally to JIS equivalents of 6xxx family.
GB/T	—	China	Not always present as a standardized grade; Chinese mills may supply 6262 under proprietary or AA‑aligned specifications.

While AA 6262 and EN AW‑6262 are commonly treated as equivalent commercial designations, national standards and certification practices can differ in allowable trace elements and allowable impurities. In some regions there is no exact JIS or GB/T equivalent, and manufacturers either provide AA/EN compliant material or specify a closely comparable 6xxx alloy such as 6061/6063 with notes on machinability differences.

Engineers sourcing overseas should request mill certificates and confirm presence and limits of free‑machining elements (Pb, Bi, Sn) and any departures in Cu content, because these small differences can materially affect machinability, weldability and corrosion behavior.

Corrosion Resistance

6262 offers good atmospheric corrosion resistance typical of 6xxx series alloys due to formation of a protective aluminum oxide layer. In mildly corrosive environments it performs acceptably without special coatings, but alloying elements (notably Cu) can modestly reduce resistance relative to near‑pure Al alloys and to 5xxx series (Al‑Mg) alloys. Regular coatings, anodizing or painting are common for exposed applications to extend service life and improve aesthetics.

In marine or high‑chloride environments 6262 is generally adequate for interior components and some external hardware, but it is not as corrosion‑resistant as Al‑Mg alloys (5xxx series) specifically engineered for seawater exposure. Crevice corrosion and pitting are concerns in chloride‑rich environments, particularly where galvanic couples to more noble materials exist or where surface damage removes oxide protection.

Stress corrosion cracking (SCC) susceptibility in 6262 is usually low compared with high‑Cu 2xxx series alloys, but under combined tensile stress and corrosive conditions some risk exists. Galvanic interactions should be managed: when mated to stainless steels or copper alloys the aluminum can suffer accelerated corrosion if not insulated. Compared with other alloy families, 6262 provides a balanced corrosion profile suitable for many general engineering applications but requires protective measures for severe marine or chemical exposure.

Fabrication Properties

Weldability
6262 welds reasonably well by common fusion processes such as MIG and TIG, but weldability depends on presence and quantity of free‑machining elements. Lead/bismuth containing variants are more difficult to weld cleanly and may promote porosity or hot‑cracking; these grades are often avoided where weld joints are required. Use filler alloys compatible with 6xxx series (such as 4043 or 5356 depending on joint requirements) and account for HAZ softening; post‑weld heat treatment or local machining allowances may be required.

Machinability
Machinability is a key advantage of many 6262 commercial variants—especially those with controlled Pb/Bi/Sn additions—delivering improved chip breaking, surface finish and tool life compared with standard 6xxx alloys. Typical machinability indices exceed those of 6061 and align closer to leaded free‑cutting alloys; carbide tooling is recommended at moderate cutting speeds with rigid fixturing to avoid chatter. Coolant, chip evacuation and appropriate tool geometry are essential for sustained productivity and surface integrity.

Formability
Formability is best in annealed (O) or lightly strain‑hardened tempers; bend radii should follow standard aluminum guidelines (internal bend radius ≥ material thickness for moderate ductility tempers). Cold working increases strength via strain hardening, but 6262 is primarily intended for parts that will be machined after heat treatment rather than heavily formed parts. For applications requiring significant forming and subsequent strength, consider forming in O temper followed by solution heat treatment and aging where geometry and distortion tolerances permit.

Heat Treatment Behavior

As a heat‑treatable alloy, 6262 responds to solution treatment, quenching and artificial aging to develop precipitate phases providing elevated strength. Solution treatment is typically carried out at temperatures in the range of ~520–540 °C, held to dissolve soluble phases and followed by rapid quench to retain solute in supersaturated solid solution. Aging (artificial) is performed at elevated temperatures (commonly ~160–185 °C) to precipitate Mg2Si and Cu‑modified phases; aging times and temperatures are selected to target T5, T6 or intermediate strength levels.

T temper transitions depend on cooling rate and aging schedule: T5 applies when parts are cooled from working temperature and then artificially aged without a prior solution treatment; T6 involves explicit solution treatment and quench prior to aging and achieves higher peak strengths. T651 indicates solution treatment, stress relief via stretching and artificial aging, which improves dimensional stability for machined components. Overaging reduces peak strength but can improve toughness and corrosion resistance; process control is therefore essential to meet design targets.

For non‑heat‑treatable behavior (relevant to H‑series variants), strengthening is achieved by work hardening and controlled strain; annealing returns the material to the soft O condition for additional forming or post‑fabrication processing. Annealing cycles must be controlled to avoid excessive grain growth which would degrade mechanical properties.

High-Temperature Performance

6262 experiences progressive strength loss with increasing temperature; usable structural strength is typically maintained up to about 100–120 °C for long‑term service, with significant reductions in yield and tensile strength above this range. Short‑term exposure to higher temperatures may be tolerated but can accelerate overaging and reduce life under cyclic loading. Oxidation of aluminum alloys is generally self‑limiting due to a protective alumina film, but at elevated temperatures this scale can grow and spall in reactive environments, reducing protection.

Thermal exposure also affects the heat‑affected zone (HAZ) around welds; localized softening and precipitate coarsening can occur if temperatures exceed aging ranges during service or fabrication. For applications requiring sustained elevated temperature performance, select alloys and tempers specifically rated for higher temperature stability or apply design safety factors to account for strength degradation. Creep resistance at elevated temperature is limited compared with high‑temperature alloys and must be evaluated for loaded, long‑duration applications.

Applications

Industry	Example Component	Why 6262 Is Used
Automotive	Machined brackets, valve bodies	Excellent machinability and adequate T6 strength for structural components
Marine	Fittings, connectors (protected locations)	Good corrosion resistance and machinability for complex hardware
Aerospace	Small fittings, actuators	Balance of strength‑to‑weight and machinability for precision components
Hydraulics / Fluid Power	Valves, manifolds, pistons	Free‑machining variants enable complex internal geometries and clean surfaces
Industrial Machinery	Shafts, bushings, housings	Machinability coupled with heat‑treatable strength reduces cycle time and cost
Electronics	Small heat spreaders, housings	Thermal conductivity and lightweight structure where electrical conductivity is secondary

6262 finds its niche where parts require both tight dimensional control from machining and the elevated strength enabled by precipitation hardening. Its free‑machining variants allow high throughput on turning and milling operations while preserving acceptable corrosion and mechanical performance. Design engineers leverage its balanced property set for components where cost, manufacturability and service requirements intersect.

Selection Insights

When considering 6262, choose it for components requiring superior machinability compared with standard 6xxx alloys while still taking advantage of precipitation hardening to achieve useful strength. Its free‑machining versions reduce cycle times and tool wear versus 6061/6063, but be mindful of reduced weldability and potential porosity if Pb/Bi/Sn levels are present.

Compared with commercially pure aluminum (1100), 6262 trades off some electrical and thermal conductivity and formability in order to provide much higher strength and improved machinability. Compared with work‑hardened alloys such as 3003 or 5052, 6262 offers higher heat‑treatable strength but somewhat lower inherent corrosion resistance in highly aggressive chloride environments. Compared with common 6xxx alloys like 6061/6063, 6262 may offer better machinability and similar or modestly lower peak strength; pick 6262 when machinability and post‑machining stability are prioritized over maximum achievable tensile strength.

Closing Summary

Alloy 6262 remains a relevant engineering material where the combination of heat‑treatable strength, excellent machinability and reasonable corrosion resistance is required. Its tailored composition and temper options make it a practical choice for precision‑machined components across automotive, hydraulic, industrial and aerospace sectors where manufacturability and mechanical performance must be balanced.