Aluminum 6013: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

Alloy 6013 is a member of the 6xxx series aluminum alloys, which are primarily Al-Mg-Si based with additions that promote precipitation hardening. It contains silicon and magnesium as the core age-hardening constituents and significant copper and manganese additions relative to common 6xxx alloys, which tailor its strength, toughness, and response to heat treatment.

6013 is a heat-treatable alloy whose primary strengthening mechanism is precipitation hardening (age hardening) via Mg2Si-related precipitates and Cu-containing phases that augment peak strength and alter toughness. Secondary contributions from controlled distributed dispersoids (Mn/Cr/Ti) refine grain structure and improve resistance to deformation and fracture initiation.

Key traits of 6013 include higher specific strength compared with 6000-series baseline alloys, good general corrosion resistance typical of Al-Mg-Si materials, and reasonable weldability when correct practices and fillers are used. It offers a balance of formability and strength that suits structural automotive, aerospace secondary structure, and precision industrial applications where elevated strength-to-weight and damage tolerance are required.

6013 is chosen over other alloys when designers need better peak strength and fatigue performance than 6061 while retaining acceptable formability and corrosion resistance. It is often selected where components require age-hardening to a higher yield and tensile envelope without jumping to the higher-cost 7xxx-series alloys that suffer poorer corrosion resistance and lower weldability.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High	Excellent	Excellent	Fully annealed, maximum ductility for forming
T4	Medium	Medium-High	Good	Good	Solution heat-treated and naturally aged
T5	Medium-High	Medium	Fair-Good	Good	Cooled from elevated temp. and artificially aged
T6	High	Medium-Low	Fair	Good	Solution treated and artificially aged to peak strength
T651	High	Medium-Low	Fair	Good	T6 with stress-relief by stretching, reduced residual stresses
H14	Medium	Medium	Good	Good	Strain-hardened mildly, used for parts needing moderate strength

Temper selection has a direct and predictable impact on mechanical performance; the O and T4 tempers favor forming operations while T6/T651 provide peak strength for structural load-bearing parts. T5 and H14 provide intermediate compromises where partial growth in strength is required without full solution-treatment cycles.

Heat treatment and subsequent tempering sequences also affect machinability and fatigue behavior, with overaging or improper ageing decreasing yield and introducing microstructural heterogeneity. Careful specification of temper (including any stress relieving like T651) is vital to control distortion, especially for machined aerospace fittings.

Chemical Composition

Element	% Range	Notes
Si	0.4–0.8	Enables Mg2Si precipitation; controls strength and extrusion behavior
Fe	≤0.7	Impurity element; high Fe forms intermetallics that can affect toughness
Mn	0.3–0.8	Grain refinement and improved strength/toughness through dispersoids
Mg	0.8–1.2	Primary element for precipitation with Si (Mg2Si) providing age hardening
Cu	0.6–1.6	Increases strength and response to aging; influences corrosion and SCC
Zn	≤0.2	Minor element; limited effect at low levels
Cr	0.04–0.35	Controls grain structure and recrystallization, improves toughness
Ti	≤0.15	Grain refiner for cast and wrought products
Others (each)	≤0.05	Trace elements and residuals with limited influence at low levels

The alloying matrix for 6013 is tuned to favor precipitation hardening (Mg + Si) while copper additions shift the precipitate chemistry to yield higher peak strengths and modified aging kinetics. Elements such as Mn and Cr form dispersoids and intermetallic particles that stabilize grain structure during processing and improve resistance to localized deformation and fracture.

Controlling Fe and Zn levels is important to prevent excessive coarse intermetallic formation that can act as fatigue crack initiation sites and reduce sheet surface quality. The combined chemistry results in an alloy that balances age-hardening response, machinability, and acceptable corrosion resistance for many structural applications.

Mechanical Properties

6013’s tensile behavior depends strongly on temper and section thickness; tensile strength increases significantly from annealed to peak-aged conditions due to fine precipitate distributions. Yield strength in T6/T651 tempers is substantially higher than in the annealed state, enabling thinner sections for equivalent load-carrying capacity, but ductility decreases correspondingly.

Elongation in O or T4 tempers is high enough for most forming operations, while peak-aged tempers (T6) typically show reduced elongation but improved fatigue endurance for cyclic structural use. Hardness trends follow strength changes, with Brinell or Vickers hardness rising as the alloy approaches peak-aging. Fatigue performance benefits from a combination of fine-scale precipitates and controlled particle distribution; machining and surface finish are important for fatigue life.

Thickness and product form influence achievable properties due to differences in cooling rate and natural aging; thin gauges achieve more uniform properties and faster natural age kinetics, while thick sections may require tailored heat treatment to ensure uniform solutioning and aging.

Property	O/Annealed	Key Temper (T6/T651)	Notes
Tensile Strength	120–180 MPa	330–380 MPa	T6 values vary with section thickness and aging cycle
Yield Strength	40–90 MPa	300–340 MPa	Defined yield for T6 can approach 300+ MPa in typical sheet/extrusions
Elongation	20–30%	8–14%	Ductility drops with increasing strength; depends on form factor
Hardness (HB)	30–60 HB	95–130 HB	Hardness correlates with precipitation state and work hardening

Physical Properties

Property	Value	Notes
Density	2.70 g/cm³	Typical for wrought Al alloys; contributes to favorable strength-to-weight
Melting Range	~555–650 °C	Solidus/liquidus range depends on local alloying concentrations
Thermal Conductivity	~150–170 W/m·K	Lower than pure Al due to solutes and precipitates; still good for heat spreading
Electrical Conductivity	~30–45 % IACS	Reduced relative to pure Al; varies with temper and alloying
Specific Heat	~900 J/kg·K	Typical value for aluminum alloys at room temperature
Thermal Expansion	~23–24 µm/m·K	Similar to other Al alloys; important for thermal design and jointing

The physical properties of 6013 mark it as a lightweight structural metal with good thermal transport relative to many alloys used in structural applications. Thermal conductivity and expansion must be accounted for in heat exchanger and bonded-assembly designs where differential expansion or localized heating occurs.

Electrical conductivity is moderate and declines after precipitation hardening; therefore 6013 is not a first choice where high electrical conductivity is required, but it remains useful for structural components with secondary thermal/electrical functions.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.3–6 mm	Uniform in thin gauges; quick natural aging	O, T4, T5, T6, T651	Widely used for automotive outer panels and structural sheets
Plate	>6 mm up to 100 mm	May have slightly lower achievable strength due to cooling	O, T4, T6	Thick plates require controlled solution treatment for homogeneity
Extrusion	5–200 mm cross-sections	Good through-thickness properties when properly heat-treated	T5, T6, T651	Profiles for structural frames and stiffeners
Tube	OD 10–200 mm	Performance depends on wall thickness and post-forming heat treatment	O, T6	Used for structural tubing and chassis members
Bar/Rod	Dia 5–100 mm	Good machinability in semi-solid and solution-treated states	O, T6	Common for fittings, fasteners, and machined components

Sheet and extrusion forms are the most common for 6013 because these shapes maximize its strength-to-weight advantage and allow efficient heat treatment. Plate and thick-section components need careful process control to avoid retained eutectic or un-solutioned regions that impair mechanical properties.

Extrusions and tubes can be produced with fairly complex cross-sections due to the alloy’s good flow characteristics in hot working, but final mechanical properties depend on the applied solution and aging cycles as well as any mechanical straightening or stress relieving operations.

Equivalent Grades

Standard	Grade	Region	Notes
AA	6013	USA	Official Aluminium Association designation for the alloy family
EN AW	6013	Europe	Common European designation; composition and tempers generally aligned
JIS	No direct equivalent (nearest: 6061)	Japan	JIS catalogues do not always include a direct 6013 counterpart; 6061 often nearest in properties
GB/T	No direct equivalent (nearest: 6061A)	China	Chinese standards may use 6061-series as a practical substitute in some specifications

Direct one-to-one equivalents are not always present in regional standards because 6013’s composition was developed to satisfy specific mechanical and processing goals. Where direct EN AW-6013 material is not available, engineers frequently substitute closely related 6xxx alloys (e.g., 6061) but must account for differences in copper and manganese that affect ageing behavior and final strength.

Always confirm property requirements and tempering sequences when substituting; material procurements and specifications should map mechanical targets rather than rely solely on alloy numbering when cross-referencing standards.

Corrosion Resistance

6013 provides good general atmospheric corrosion resistance attributable to the protective aluminum oxide film that self-heals under typical service conditions. Its performance in industrial and urban atmospheres is satisfactory when properly anodized or coated, and it resists stress-corrosion cracking better than many high-strength 7xxx alloys.

In marine environments 6013 shows reasonable resistance but is not as durable as specific Al-Mg (5xxx series) alloys designed for chloride-rich exposure. Copper additions increase susceptibility to localized corrosion and can slightly reduce the pitting resistance compared with low-copper 6xxx alloys; protective coatings or sacrificial cathodic measures are common for long-term marine service.

Galvanic interactions must be considered when 6013 is mated to more noble materials (e.g., stainless steels); isolating materials or coatings are recommended to prevent accelerated corrosion of the aluminum alloy. Overall, 6013 sits between the highly corrosion-resistant 5xxx series and the stronger but more SCC-prone 7xxx series in terms of overall corrosion and cracking behavior.

Fabrication Properties

Weldability

6013 can be welded by common fusion processes such as TIG and MIG with proper joint design and filler selection, though the presence of copper requires attention to filler chemistry to minimize hot cracking and post-weld softening. Filler alloys with silicon additions (e.g., Al-Si type fillers) are commonly used to improve flow and reduce cracking tendency; choice depends on required post-weld strength and corrosion performance.

The heat-affected zone (HAZ) in welds will typically exhibit some softening relative to the T6 parent metal because precipitates coarsen and solutionize during welding, reducing local yield strength. Post-weld heat treatment is sometimes used to restore strength for critical applications, but distortion and residual stresses must be managed during such treatments.

Machinability

6013 has good machinability compared with many high-strength aluminum alloys due to its relatively moderate hardness in solution-treated and annealed conditions. Carbide tooling with positive rake and appropriate coatings (TiAlN/PVD) achieves high metal removal rates; cutting speeds should be conservative relative to free-machining aluminum grades to avoid work hardening and built-up edge formation.

Chip control is generally manageable but continuous chips can form; use of flood coolant and chip breakers is recommended to maintain dimensional accuracy and tool life. Fine finishes achievable after aging make 6013 suitable for precision machined fittings and aerospace components.

Formability

Forming operations favor O and T4 tempers for 6013; these conditions allow tighter bend radii and complex stamping operations without cracking. In peak-aged states (T6) the alloy’s reduced elongation restricts severe forming; in such cases parts are often formed in softer tempers and then solution-treated/aged or formed after partial aging sequences.

As a guideline, minimum outside bend radii for drawn or bent components typically range from 2× to 4× material thickness in properly specified tempers, depending on tooling, lubrication, and grain orientation. Springback is moderate and must be accounted for in die development for precision parts.

Heat Treatment Behavior

As a heat-treatable alloy, 6013 is brought to strength by solution treatment, quenching and artificial aging paths that produce finely dispersed precipitates. Typical solution treatment temperatures are in the range of 525–555 °C, chosen to dissolve Mg, Si and Cu into solid solution without incipient melting of low-melting constituents; water quenching is used to retain the supersaturated solution prior to aging.

Artificial aging to T6 temper typically occurs at 150–180 °C for several hours, creating coherent and semi-coherent precipitates that raise both yield and tensile strength; copper alters the precipitation sequence and sometimes accelerates peak ageing relative to binary Mg-Si systems. T5 temper (cooled from elevated temperature, artificially aged) is used where full solution treatment is impractical, but it yields slightly lower peak properties.

Overaging increases ductility and lowers strength and is used where improved stress corrosion resistance or dimensional stability is required. T651 and similar designations indicate stress relief (stretching or low-temperature bake) after solution treatment to control residual stresses for precision parts.

High-Temperature Performance

6013, like other 6xxx series alloys, experiences noticeable strength reduction above ~125–150 °C as precipitates coarsen and lose coherency; design against creep and sustained stress at elevated temperatures should use conservative allowable stresses. Short-term exposure to higher temperatures may be tolerated, but prolonged service above aging temperatures will lead to permanent strength degradation and potential dimensional drift.

Oxidation at service temperatures is limited because aluminum forms a protective oxide layer; however, at elevated temperatures oxidation can increase surface roughness and complicate thermal joining. The HAZ of welded or brazed assemblies can be particularly susceptible to property changes under cyclic thermal loading, necessitating post-process tempering or design allowances.

Applications

Industry	Example Component	Why 6013 Is Used
Automotive	Seat frames, structural reinforcements	High strength-to-weight and fatigue performance
Marine	Small structural brackets and fittings	Balanced corrosion resistance and strength
Aerospace	Secondary structural fittings, actuator housings	High specific strength and good machinability
Electronics	Enclosures and thermal carriers	Adequate thermal conductivity and dimensional stability

6013 is advantageous where designers require higher strength than standard 6xxx alloys but want to avoid the corrosion and manufacturability penalties of high-strength 7xxx series materials. The alloy’s combination of age-hardening response and machinability makes it valuable for medium-duty structural components across automotive, aerospace, and industrial equipment.

Selection Insights

Choose 6013 when you need a stronger, heat-treatable 6xxx alloy with better fatigue and machinability performance than baseline alloys. It is particularly attractive when moderate increases in peak strength and improved fracture resistance are required without the sacrifice of weldability and general corrosion performance.

Compared with commercially pure aluminum (1100), 6013 sacrifices electrical conductivity and the very high formability for substantially improved tensile and yield strength, enabling lighter, stiffer structural designs. Versus work-hardened alloys such as 3003 or 5052, 6013 provides higher peak strength and better fatigue response but requires heat treatment and controlled tempering, and it is slightly more sensitive to localized corrosion.

When compared with common heat-treatable alloys like 6061 or 6063, 6013 is selected where its copper and manganese additions give a tailored aging response and enhanced fatigue/strength envelope despite overlapping tempers. Use 6013 where a targeted balance of machinability, achievable T6 strength, and acceptable corrosion resistance is prioritized over lowest-cost or maximum electrical conductivity.

• Select 6013 for medium-to-high strength machined or stamped parts that require good fatigue life.
• Prefer O/T4 tempers for complex forming and T6/T651 for final structural performance.
• Confirm availability and supplier capability for required tempers and forms before design freeze.

Closing Summary

Alloy 6013 remains a practical choice where engineers need a heat-treatable aluminum that delivers higher strength and enhanced fatigue performance than baseline 6xxx alloys while maintaining good formability and weldability. Its tuned chemistry and temper options make it versatile for automotive, aerospace, marine, and industrial components where a balance of strength, corrosion resistance, and manufacturability is critical.