Aluminum 1A60: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

1A60 is a heat-treatable aluminum alloy belonging to the 6xxx series (Al-Mg-Si family) characterized by balanced strength, formability and corrosion resistance. Its primary alloying additions are magnesium and silicon which form Mg2Si precipitates during artificial aging to produce peak-strength conditions. The alloy relies on precipitation hardening (solution heat treatment, quench, and artificial aging) as the principal strengthening mechanism, with secondary effects from grain structure and light cold work.

Key traits of 1A60 include moderate-to-high strength in T6/T5 tempers, good extrudability and surface finish for anodizing, appreciable resistance to general atmospheric and industrial corrosion, and good weldability using common filler wires. Formability in annealed and naturally aged conditions is excellent for drawn and bent components, while heat-treated tempers offer higher static strength at the cost of ductility. Typical industries using this family of alloys include automotive body and structural components, architectural extrusions, transportation equipment, and general engineering fabrication where an optimized strength-to-weight and corrosion balance is required.

Engineers choose 1A60 where a combination of extrudability, finishing quality, and moderate peak strength is required without the higher copper levels of 2xxx or the strength penalties of pure Al. It is often selected over softer 1xxx or 3xxx alloys when stiffness and design strength are necessary, and over higher-strength 7xxx alloys when corrosion performance, weldability, and lower anisotropy are priorities. The overall lifecycle advantages often include lower processing complexity and predictable age-hardening response for consistent production parts.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High	Excellent	Excellent	Fully annealed condition, maximum ductility for deep drawing
H14	Low-Medium	Medium	Very Good	Very Good	Partial strain-hardened, used for light structural sheet components
T4	Medium	Medium-High	Very Good	Very Good	Solution heat treated and naturally aged; good forming temperament
T5	Medium-High	Medium	Good	Good	Cooled from hot working and artificially aged to moderate strength
T6	High	Medium-Low	Limited	Good	Solution treated, quenched and artificially aged to peak strength
T651	High	Medium-Low	Limited	Good	T6 with stress-relief by stretching; used for structural extrusions

Temper controls the volume fraction and distribution of Mg2Si precipitates and therefore tunes the strength versus ductility balance. Annealed and low-strength tempers (O, H14, T4) maximize formability for deep drawing and bending, whereas T5/T6 produce the precipitate structure that gives higher yield and tensile strength at reduced elongation.

Chemical Composition

Element	% Range	Notes
Si	0.2–0.7	Controls Mg2Si precipitation, influences extrudability and strength
Fe	0.1–0.35	Impurity element; affects intermetallic particle content and strength
Mn	0.05–0.20	Grain structure control and moderate strengthening
Mg	0.3–0.9	Main strengthening element forming Mg2Si with Si
Cu	0.0–0.15	Small additions raise strength and affect age-hardening response
Zn	0.0–0.25	Minor; excessive amounts can reduce corrosion resistance
Cr	0.0–0.1	Controls grain growth and recrystallization during thermal cycles
Ti	0.0–0.1	Grain refiner in cast or wrought processing
Others	Balance Al	Trace elements and residuals controlled to maintain performance

The combined Mg and Si content establishes the alloy’s precipitate chemistry and therefore the achievable peak hardness and yield. Minor elements such as Cr and Mn are used to control recrystallization and grain size, improving strength retention after thermal exposure and enhancing toughness; Fe and other impurities are minimized to limit deleterious intermetallics that harm surface finish and fatigue initiation.

Mechanical Properties

In tensile behavior 1A60 demonstrates a pronounced increase in yield and ultimate tensile strength when transformed from a solution-treated and artificially aged condition to T5/T6 tempers. The alloy typically shows continuous yield behavior with a clear yield point in higher-strength tempers, and ductility falls as precipitate density increases. Age hardening can be tuned to prioritize yield strength (shorter aging at higher temperatures) or toughness (overaging).

Yield and tensile levels are thickness-dependent; thin extrusions and sheets reach target hardness and strength faster during aging than thick plates due to faster quench and more uniform precipitation. Fatigue performance is influenced by surface condition and residual intermetallics; properly processed extrusions and anodized surfaces show competitive high-cycle fatigue life comparable to other 6xxx alloys. Hardness in T6 is significantly higher than in annealed condition and correlates with tensile properties, while HAZ softening near welds can reduce local yield strength.

Property	O/Annealed	Key Temper (e.g., T6)	Notes
Tensile Strength	100–140 MPa	200–260 MPa	Range depends on section thickness and exact composition
Yield Strength	45–80 MPa	150–240 MPa	Yield increases markedly with artificial aging
Elongation	18–30%	8–16%	Ductility reduces as precipitate density increases
Hardness	25–40 HV	60–95 HV	Vickers hardness proportional to strength state

Physical Properties

Property	Value	Notes
Density	2.70 g/cm³	Typical for Al alloys; contributes to good specific strength
Melting Range	570–640 °C	Solidus–liquidus range depends on alloying and impurities
Thermal Conductivity	140–170 W/m·K	Lower than pure Al due to solute scattering; still good for heat sinks
Electrical Conductivity	28–40 % IACS	Alloying reduces conductivity compared with pure Al
Specific Heat	~0.90 J/g·K	Typical aluminum specific heat at ambient temperatures
Thermal Expansion	23–24 µm/m·K (20–100 °C)	Moderate expansion; important for thermal design and joining

The physical properties reflect the balance between metallic aluminum matrix and solute atoms/precipitates which reduce conductivity and thermal transport compared with pure Al. Density and specific heat make the alloy attractive for applications where lightweight thermal mass and moderate heat conduction are required, such as enclosures and heat spreader structures.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.3–6 mm	Uniform thickness, reaches age-hardening evenly	O, H14, T4, T5, T6	Widely used for panels, cladding, and stamped parts
Plate	6–50+ mm	Slower quench rates; peak properties harder to attain in thick sections	O, T4, T6	Thick sections require controlled quenching to avoid soft cores
Extrusion	Complex profiles, up to several meters	Excellent directional properties along profile axis	T5, T6, T651	Optimal for architectural frames, rails, and structural sections
Tube	0.5–25 mm wall	Similar behavior to sheet for thin-walled tubes	O, T4, T5, T6	Used for structural and fluid-carrying applications
Bar/Rod	Diameters up to 200 mm	Homogeneous properties in small diameters	O, T6	Used for machined components and fasteners

Forming route and product form significantly influence achievable properties; extrusions and thin sheets can be rapidly quenched leading to more uniform T6 properties, while thick plates may harbor soft cores unless homogenized and quenched under controlled conditions. Surface finish and anodizing compatibility make extruded sections particularly valuable for architectural and visible applications, whereas plate and bar are preferred where machining and static load-bearing capacity dominate.

Equivalent Grades

Standard	Grade	Region	Notes
AA	1A60	USA	Industry identification used in selected catalogs and suppliers
EN AW	6060 / 6063 equiv.	Europe	Closest common European equivalents in performance and chemistry
JIS	A6060	Japan	Similar Al-Mg-Si series designation for extrudable alloys
GB/T	6060	China	Comparable composition and typical usages in extrusions

Equivalent grades listed approximate the general chemistry and behavior of 1A60 but differ in permitted impurity levels, precise Si/Mg ratios, and heat-treatment response. These subtle differences affect aging kinetics, surface quality after anodizing, and elevated-temperature stability; users should cross-reference specific standard sheets and supplier certificates when substituting across regions.

Corrosion Resistance

1A60 exhibits good general atmospheric corrosion resistance inherent to Al-Mg-Si alloys, with the naturally forming alumina film providing protection in industrial and urban environments. In sea-air and marine splash zones the alloy performs acceptably but benefits from protective coatings or anodizing for long-term exposure; pitting can occur at crevices or under deposits if chlorides are present. Localized corrosion is mitigated by low copper content and controlled impurity levels; however, mechanical damage to the oxide film will locally accelerate attack until re-passivation occurs.

Stress corrosion cracking susceptibility in Al-Mg-Si alloys is low compared with high-strength Al-Zn-Mg (7xxx) families, but SCC can appear under tensile stress and corrosive environments particularly if over-aged condition is not controlled. Galvanic coupling with more noble metals (e.g., stainless steel, copper) will drive the aluminum toward accelerated anodic corrosion; designers should isolate dissimilar metals or provide coatings and appropriate fastener selection. Compared with 5xxx (Al-Mg) alloys, 1A60 trades slight reductions in pure chloride resistance for improved extrusion surface quality and age-hardenable strength.

Fabrication Properties

Weldability

1A60 welds readily with conventional fusion processes such as MIG/GMAW and TIG/GTAW, exhibiting low sensitivity to hot-cracking relative to higher-copper alloys. Preferred filler materials are ER4043 (Al-Si) for improved flow and reduced porosity, or ER5356 (Al-Mg) when higher post-weld strength is required, noting that ER5356 can slightly reduce corrosion resistance in aggressive environments. Users must account for HAZ softening; post-weld artificial aging or local re-heat treatments can restore strength for critical structural joints.

Machinability

Machinability of 1A60 is moderate and comparable to other 6xxx series alloys, with favorable chip control in wrought forms and predictable tool wear when using carbide tooling. Recommended practice includes high rake carbide inserts, rigid workholding and coolant to prevent built-up edge; conventional cutting speeds for turning are moderate versus free-cutting 2xx families. Drilling and tapping require attention to chip evacuation in deep holes and selection of clearances to avoid galling.

Formability

Formability in O, H14 and T4 tempers is excellent: bend radii as low as 1–2× material thickness are feasible for sheet, depending on alloy thickness and tool geometry. Cold working and strain-hardening increase strength (H tempers) but reduce elongation; therefore complex stamping is usually performed in soft tempers followed by age hardening where dimensional stability is required. For tight-radius extrusions and drawn parts, pre-aging strategies and controlled solution treatment can reduce springback and improve final dimensional control.

Heat Treatment Behavior

As a heat-treatable Al-Mg-Si alloy, 1A60 is responsive to the traditional solution treatment, quench and artificial aging cycle. Solution treatment is typically performed at 520–550 °C to dissolve Mg2Si into the solid solution, followed by rapid quench (water or polymer quenchant) to retain a supersaturated solid solution. Artificial aging at 150–180 °C precipitates fine Mg2Si particles, with peak hardness (T6) achieved as a function of time and temperature; T5 and T6 trades time and temperature for production convenience.

T temper transitions are controllable: T4 (natural age) allows forming before final artificial aging, whereas T5 (cooled from working temperature and artificially aged) provides economical strength for extrusions. Overaging reduces peak strength but improves toughness and stress-corrosion resistance; designers can specify T6, T651 or an overaged temper depending on service stress and environment. Non-heat-treatable strengthening relies on work hardening and annealing cycles; however, for 1A60 the primary design lever is precipitation heat treatment rather than cold-work.

High-Temperature Performance

1A60 retains useful mechanical properties up to moderate temperatures, but precipitate strengthening begins to deteriorate above roughly 120–150 °C as coarsening of Mg2Si reduces yield and tensile strength. Continuous service at elevated temperature causes progressive softening and potential loss of dimensional stability due to over-ageing and recovery processes; short excursions to higher temperature are tolerated but prolonged exposure will require specification of overaged tempers or alternate alloys. Oxidation of aluminum is self-limiting under normal atmospheric conditions, but elevated temperature in aggressive environments (sulfidizing or halide-containing atmospheres) can accelerate surface degradation.

In welded structures exposure to elevated temperatures exacerbates HAZ softening effects, potentially creating localized sections of lower strength; designers should assess load paths and thermal cycles when specifying joints for service above ambient. For prolonged high-temperature structural applications, consider alloys specifically formulated for thermal stability or use mechanical design compensations for reduced strength.

Applications

Industry	Example Component	Why 1A60 Is Used
Automotive	Window frames, extruded trim, body stiffeners	Good extrudability, corrosion resistance and moderate strength
Marine	Superstructure and architectural fittings	Balanced corrosion resistance and surface finish for anodizing
Aerospace	Interior structural fittings, non-critical brackets	Favorable strength-to-weight and good machinability
Electronics	Heat sinks, chassis	Moderate thermal conductivity and ease of extrusion for profiles

1A60 is often selected where a mix of formability, surface finish, and age-hardenable strength is required for medium-duty structural and architectural components. Its versatility across sheet, extrusion and machined forms makes it a go-to alloy for integrated designs where post-form age-hardening can optimize performance without introducing complex fabrication steps.

Selection Insights

If your priority is maximum electrical conductivity and formability (deep drawing, high ductility), commercially pure aluminum such as 1100 will outperform 1A60 in those metrics, but 1A60 offers materially higher yield and tensile strength through age hardening. Choose 1A60 when you need a compromise: significantly higher mechanical strength at modest loss of conductivity compared with 1100, while retaining good finishing and corrosion properties.

Compared with common work-hardened alloys like 3003 or 5052, 1A60 provides higher achievable peak strength through heat treatment while maintaining similar or slightly reduced corrosion resistance depending on alloying and finish. Use 1A60 over 3xxx/5xxx when design calls for higher stiffness, dimensional stability after aging, or when extrusion surface quality is critical.

Against higher-strength heat-treatable alloys such as 6061 or 7075, 1A60 may have lower absolute peak strength than 6061-T6 in some compositions but offers advantages in extrudability, surface finish for anodizing, and often better weldability and corrosion resistance. Select 1A60 when manufacturability, surface quality and consistent age-hardening behavior take priority over attaining the highest possible strength.

Closing Summary

1A60 remains a practical, versatile Al-Mg-Si alloy that balances extrudability, surface quality, corrosion resistance and age-hardenable strength for a wide range of structural and architectural components. Its tunable tempers, predictable precipitation response and compatibility with common fabrication routes keep it relevant for modern engineering applications that require a pragmatic trade-off between performance and manufacturability.