Aluminum 5150: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

5150 is an aluminum alloy placed in the 5xxx series, a family defined by magnesium as the principal alloying element. This series is characterized by alloys that are non-heat-treatable and strengthened primarily by solid-solution strengthening and strain hardening rather than precipitation hardening used by 6xxx and 7xxx alloys.

Major alloying ingredients in 5150 are aluminum with a significant magnesium fraction, together with minor amounts of manganese, chromium, and iron as typical residuals. The strengthening mechanism is predominantly work-hardening (strain hardening) and solution strengthening from Mg in solid solution; there is no significant age-hardening response to conventional T-temper treatments.

Key traits of 5150 include high elevated strength for a non-heat-treatable alloy, very good corrosion resistance in many atmospheric and marine conditions, and generally good formability in softer tempers. Weldability is favorable with MIG/TIG processes when proper filler metals are used, and 5150 is selected frequently where a balance of strength, weldability, and corrosion resistance is required such as in marine, transportation, and certain structural applications.

Compared with other aluminum families, 5150 is chosen when designers need better strength than pure Al or mild 3xxx work-hardened alloys, but want to avoid the cost, distortion sensitivity, or lower corrosion resistance of high-strength heat-treatable alloys. Its combination of mechanical performance and resistance to seawater makes it attractive for hulls, structural members, and components that must be formed then welded.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High (20–35%)	Excellent	Excellent	Fully annealed, maximum ductility
H111	Moderate	Good (15–25%)	Very Good	Very Good	Slightly cold worked, general-purpose
H14	Moderate-High	Moderate (10–20%)	Good	Very Good	Single-step strain-hardened, common sheet temper
H22	High	Moderate (8–15%)	Fair	Good	Strain-hardened and thermally stabilized
H32	High	Moderate (8–12%)	Fair	Good	Strain-hardened then stabilized for welding
H116	High	Lower (6–12%)	Limited	Good	Strain-hardened and stress-relieved for marine use
H321	High	Lower (6–12%)	Limited	Good	Cold-worked and stabilized by low-temperature treatments

Temper has a strong influence on mechanical performance and forming behavior for 5150. Softer tempers (O, H111) provide the best stretch and deep-draw formability, while higher H-tempers increase strength by dislocation density at the expense of elongation and bendability.

When selecting a temper, consider downstream operations such as bending, drawing, and welding: choose softer tempers for extreme forming or H32/H116 for welded assemblies that require higher as-fabricated strength and reduced post-weld distortion.

Chemical Composition

Element	% Range	Notes
Si	0.10–0.40	Impurity element; higher Si reduces ductility and slightly increases strength
Fe	0.40–1.00	Typical residual; forms intermetallics that can affect surface finish
Mn	0.10–0.50	Improves strength and grain structure control
Mg	3.0–5.5	Principal strengthening element; increases strength and corrosion resistance
Cu	0.00–0.20	Kept low to preserve corrosion resistance; small amounts increase strength
Zn	0.00–0.25	Low levels; higher Zn can lower corrosion resistance
Cr	0.05–0.30	Controls grain structure and improves resistance to recrystallization
Ti	0.00–0.10	Grain refiner; used in small amounts for cast or wrought processing
Others	0.05–0.15	Trace elements and impurities; balance Al

The Mg content is the dominant factor setting 5150’s mechanical and corrosion behavior: as Mg rises, solid solution strengthening increases and sacrificial behavior in marine environments improves. Minor elements such as Mn and Cr are deliberately controlled to refine grain structure, stabilize dislocations during processing, and reduce susceptibility to grain-boundary-related failures.

Mechanical Properties

5150 exhibits tensile behavior typical of higher-Mg 5xxx alloys: a relatively flat strain hardening curve after yield and good uniform elongation in softer tempers. Yield strength and ultimate tensile strength increase with cold work and stabilization, while ductility and total elongation fall; thus trade-offs are predictable and repeatable for production control.

Hardness correlates with temper and cold work; annealed 5150 is relatively soft and very workable, while Hxx tempers can reach hardness levels suitable for moderately loaded structural components. Fatigue resistance is generally good for a non-heat-treatable alloy, but it is sensitive to surface condition and weld-induced HAZ softening, so design should control surface finish, notches, and weld profiles.

Thickness influences properties: as-gauge decreases, achievable strain hardening during forming changes, and cooling rates during any thermal stabilization affect residual stresses. For thick plate forms, grain size and work-hardening response can differ, requiring temper-specific property verification.

Property	O/Annealed	Key Temper (H116/H32)	Notes
Tensile Strength	120–170 MPa	280–350 MPa	Wide range due to Mg level and cold work; values depend on supplier and gauge
Yield Strength	40–90 MPa	180–300 MPa	Yield rises strongly with strain hardening and stabilization
Elongation	20–35%	6–15%	Ductility drops as strength increases; gauge dependent
Hardness	25–45 HB	80–120 HB	Brinell hardness correlates with temper and cold work

Physical Properties

Property	Value	Notes
Density	2.66 g/cm³	Typical for Al-Mg wrought alloys
Melting Range	570–645 °C	Solidus–liquidus range influenced by alloying additions
Thermal Conductivity	120–150 W/m·K	Lower than pure Al but still high for heat-sinking use
Electrical Conductivity	28–40 % IACS	Reduced by Mg and other solutes compared with pure Al
Specific Heat	~0.90 J/g·K	Approximate at room temperature
Thermal Expansion	23–24 ×10^-6 /K	Similar to many aluminum alloys; consider in joint design

5150 retains the favorable thermal conductivity and heat capacity of aluminum alloys, making it useful for components that require reasonable heat dissipation. Its electrical conductivity is lower than pure aluminum but acceptable for many structural or bus-bar applications where conductivity is not the primary requirement.

The thermal expansion coefficient must be accounted for when combining 5150 with dissimilar materials, especially in marine or automotive assemblies where cyclic temperature changes occur. Density and melting range are consistent with wrought Al-Mg alloys, influencing casting avoidance and welding processes.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.3–6.0 mm	Responds well to strain hardening	O, H111, H14, H32	Used for body panels, enclosures, and formed parts
Plate	6–100+ mm	Lower as-rolled ductility; heavier sections	O, H111, H22	Structural plate for marine and transportation applications
Extrusion	Cross-sections several mm to 200+ mm	Orientation affects yield and tensile directionally	O, H112, H32	Profiles for framing, rails, and structural extrusions
Tube	OD 10–300 mm	Cold-work affects roundness and mechanicals	O, H111, H32	Welded or seamless tubing for structural use
Bar/Rod	Dia 5–200 mm	Typical wrought bar properties	O, H111	Used for machined fittings and fasteners

Sheets are commonly used where forming and subsequent welding are required; thin-gauge sheets can achieve high strains in forming operations before aging is a concern. Plate is produced for structural components; thicker sections require careful control of rolling and solution/pulse-stabilization to maintain uniform properties through thickness.

Extrusions allow complex cross-sections where anisotropy from rolling is acceptable or can be designed for; bars and rods are typically supplied in softer tempers for machining, then strain-hardened if higher strength is needed.

Equivalent Grades

Standard	Grade	Region	Notes
AA	5150	USA	Aluminium Association designation for this Mg-bearing wrought alloy
EN AW	5150	Europe	EN designation typically matches AA series but check supplier data sheets
JIS	A5150	Japan	Japanese equivalents exist with similar Mg levels; verify mechanical specs
GB/T	5150	China	Chinese standard numbers may vary slightly; chemical ranges commonly aligned

Cross-standard equivalence is generally close for wrought 5xxx alloys, but manufacturers and standards bodies may apply differing limits for trace elements and mechanical requirements. Engineers should verify supplier mill certificates and regional standard revisions to ensure the exact chemical and mechanical tolerances meet design intents.

Subtle differences often appear in permitted Fe/Si/Mn residuals, temper definitions, and allowable thickness ranges; these can affect formability, weld performance, and corrosion thresholds in critical applications.

Corrosion Resistance

5150 offers very good atmospheric corrosion resistance, representative of higher-Mg 5xxx alloys, with enhanced performance in marine and coastal environments compared with Al-Cu alloys. Its resistance to pitting and general corrosion is favorable when the alloy is clean and properly finished, particularly when protective coatings or anodizing are applied.

In marine environments, 5150 exhibits good resistance to seawater exposure; however, design must consider galvanic interactions with more noble materials. Coupling to stainless steels or copper-rich alloys without appropriate isolation can lead to accelerated corrosion of the aluminum component.

Stress corrosion cracking (SCC) susceptibility in 5xxx alloys tends to increase with higher Mg content and higher strength tempers; stabilized tempers such as H116 are formulated to mitigate SCC under welding and service conditions. Compared to 6xxx and 7xxx series, 5150 is generally more resistant to intergranular corrosion in as-fabricated conditions but less resistant than pure Al for uniform corrosion.

Galvanic compatibility, protective coatings, and joint design are critical controls for marine and industrial deployment. When used correctly, 5150 provides an excellent balance of corrosion resistance and mechanical performance versus many commercial alternatives.

Fabrication Properties

Weldability

5150 welds well with common gas-shielded methods (MIG/GMAW, TIG/GTAW) when appropriate filler metals such as 5xxx series (e.g., ER5356 or ER5183 equivalents) are used. Hot-cracking risk is low to moderate; control of heat input and pre/post-weld stabilization reduces HAZ softening and residual stress-related distortions.

Welds can show a localized reduction in strength where the HAZ is softened relative to the cold-worked parent material; use of stabilization treatments (H116-style) and mechanized welding procedures reduce variability. Avoid fillers with significant Cu content if corrosion resistance is a priority.

Machinability

Machinability of 5150 is moderate; the alloy machines better than many older, tougher Al-Mg alloys but worse than free-machining Al alloys specifically designed for turning. Carbide tooling with positive rake geometry and rigid setups is recommended; moderate cutting speeds and generous coolant flow reduce built-up edge and improve surface finish.

Chip formation tends toward continuous ribbons; chip breakers or interrupted cuts may be required on slender parts. Drill point angle and peck drilling strategies help control burr formation and hole quality in thin-gauge components.

Formability

Cold formability is excellent in softer tempers (O, H111), allowing deep drawing, bending, and hydroforming operations with tight radii when springback is accounted for. As tempers move into H32/H116, bend radii must be increased and punch/die clearances adjusted for reduced elongation.

Warm forming can expand formability windows for complex shapes, and controlled pre-strain sequences improve consistency. For severe forming requirements, specify O or H111 and consider post-form stabilization if the part will be welded.

Heat Treatment Behavior

5150 is a non-heat-treatable alloy; mechanical strengthening is achieved primarily through cold work (strain hardening) and the retention of magnesium in solid solution. Thermal stabilization (low-temperature bake or stress relief) can be used after forming or welding to set mechanical properties and reduce residual stresses without the age-hardening behavior seen in 6xxx alloys.

Solution treatment and precipitation aging routes used for heat-treatable alloys do not produce significant age-hardening in 5150, so T6/T7 cycles are not applicable. Annealing restores ductility through recrystallization; controlled anneals followed by rapid cooling produce a ductile O-temp condition suitable for extensive forming.

Work hardening is repeatable and can be designed into the manufacturing flow: typically parts are formed in O or H111, then cold-worked to an Hxx of desired strength, possibly followed by a stabilization bake to minimize natural aging or stress relaxation during service.

High-Temperature Performance

5150 retains moderate strength at elevated temperatures but shows progressive strength loss as the temperature approaches 150–200 °C, with notable softening above these ranges. For intermittent exposures up to ~150 °C the alloy maintains useful mechanical performance; continuous service at higher temperatures is not recommended for load-bearing applications.

Oxidation is minimal for aluminum alloys at typical service temperatures, but scaling and surface changes can occur in aggressive thermal environments or prolonged elevated temperatures. The HAZ near welds can experience further softening with localized heating, so control of welding heat input and post-weld stabilization is important for thermal cycles.

Creep resistance at elevated temperature is limited relative to specialized heat-resistant alloys, so 5150 should be avoided for sustained high-temperature load-bearing components. Consider alternative alloys or designs where sustained temperatures and stresses overlap significantly.

Applications

Industry	Example Component	Why 5150 Is Used
Marine	Hull panels, deck structures	Excellent seawater corrosion resistance and good formability
Automotive & Transportation	Lightweight chassis components, tankage	High strength-to-weight and weldability for fabricated assemblies
Aerospace (secondary)	Fittings, brackets	Good strength and corrosion resistance for non-primary structural parts
Electronics & Thermal Management	Chassis, heat spreaders	Adequate thermal conductivity combined with formability
Architectural	Facades, cladding	Durable finishability and corrosion resistance in coastal installations

5150 is selected where designers need a corrosion-resistant, weldable aluminum with higher strength than pure or 3xxx series alloys but without the processing complications of high-strength heat-treatable alloys. Its versatility across forming, welding, and moderate machining tasks makes it suitable for fabricated structural elements.

Selection Insights

When choosing 5150, prioritize applications requiring marine-grade corrosion resistance, good weldability, and moderate-to-high strength from work-hardening. Select softer tempers for complex forming and H32/H116 for welded structures that require predictable in-service performance.

Compared with commercially pure aluminum (e.g., 1100): 5150 trades higher strength for somewhat reduced electrical conductivity and a modest loss in intrinsic formability; choose 1100 when conductivity and ease of forming are primary drivers. Compared with common work-hardened alloys (e.g., 3003 / 5052): 5150 typically delivers higher strength with similar or improved corrosion resistance, but may be less formable than 3003 in identical tempers. Compared with heat-treatable alloys (e.g., 6061 / 6063): 5150 won’t reach the peak aged strengths of 6xxx series but offers better seawater corrosion resistance and simpler fabrication (less distortion, no quench/age cycles), making it preferable for welded marine or transport structures.

Practical selection checklist: - Use O or H111 for severe forming operations and transition to H32/H116 if welding and service strength are required. - Specify appropriate filler metals (5xxx-series fillers) for weld corrosion compatibility. - Verify mill certs for Mg content and temper definitions to control SCC susceptibility and expected mechanical properties.

Closing Summary

5150 remains a relevant and pragmatic choice when designers require a corrosion-resistant, weldable aluminum with elevated strength achievable by cold work. Its balance of formability (in softer tempers), predictable work-hardening response, and marine-grade durability makes it a dependable alloy for transportation, marine, and fabricated structural applications.