Aluminum 5657: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

5657 is a member of the 5xxx series of wrought aluminum–magnesium alloys, placing it firmly in the non-heat-treatable, strain-hardened family favored for a balance of strength and corrosion resistance. Its primary alloying element is magnesium, supplemented by controlled additions of manganese and trace elements (chromium, iron, silicon, titanium) to control grain structure, strength and formability.

Strengthening is achieved almost entirely through solid-solution strengthening from magnesium and by work hardening; 5657 is engineered to respond well to cold deformation and to a range of H-temper stabilizations rather than to thermal age hardening. Key traits include elevated yield and tensile strength relative to pure aluminum, good resistance to general and pitting corrosion in marine atmospheres, and good weldability with typical Al–Mg filler alloys; formability is good in annealed or light-worked tempers but decreases with higher strain hardening.

Typical industries include transportation (automotive and heavy truck components), marine equipment and shipbuilding, structural and architectural applications, and certain electrical and heat-transfer components where strength-to-weight and corrosion resistance are valued. Engineers select 5657 over other alloys when a higher-strength, weldable aluminum with good marine corrosion resistance is needed while retaining workable formability and competitive cost.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High (20–30%)	Excellent	Excellent	Fully annealed, maximum ductility for deep drawing and complex forming
H14	Medium	Moderate (8–12%)	Good	Excellent	Light strain-hardening, common for formed sheet where extra strength is needed
H22	Medium-High	Moderate (6–10%)	Fair	Excellent	Strain-hardened then stabilized to reduce natural aging effects
H32	High	Lower (5–8%)	Fair to Good	Excellent	Strain-hardened and stabilized; common for structural panels
H111	Variable	Variable	Good	Excellent	Single-step controlled strain temper for extrusions and rolled products

Temper selection strongly steers the trade-off between formability and strength; annealed O temper gives the best forming window while H-tempers increase yield and tensile but reduce elongation. In welding or where local deformation follows welding, stabilized tempers (H22, H32) are chosen to limit post-weld softening and to manage dimensional stability.

Chemical Composition

Element	% Range	Notes
Si	0.10–0.40	Kept low to limit brittle intermetallics and to improve corrosion resistance
Fe	0.20–0.60	Typical impurity; controlled to prevent coarse Fe-rich phases that reduce ductility
Mn	0.20–0.80	Grain refiner and strength stabilizer; improves resistance to recrystallization
Mg	4.8–5.8	Principal strengthening element providing solid-solution strength and increased corrosion resistance
Cu	0.05–0.20	Minimized to avoid significant loss of corrosion resistance and to maintain weldability
Zn	0.05–0.30	Low levels limit susceptibility to intergranular corrosion and maintain ductility
Cr	0.05–0.25	Controls grain structure and improves resistance to sensitization and stress-corrosion cracking
Ti	0.02–0.10	Grain refiner used primarily in cast or billet feedstock to control microstructure
Others (each)	≤0.05	Residuals and trace elements; Al balance

The magnesium content is the dominant driver of alloy performance, raising tensile and yield strengths through solid-solution effects and contributing to improved seawater corrosion resistance. Manganese and chromium act as microalloying agents to control grain growth and mitigate recrystallization and sensitization, which improves toughness and SCC resistance in service.

Mechanical Properties

Tensile behavior in 5657 shows a combination of high proof stress and moderate ductility that depends strongly on temper and thickness. In annealed condition the alloy exhibits substantial elongation and lower yield, while strain-hardened tempers raise proof stress considerably and reduce ductility. Yield and ultimate tensile strengths scale with cold work level; typical failure modes are ductile with microvoid coalescence in well-formed test specimens.

Hardness follows the same trend as strength, increasing with H-temper level and with additional cold work. Fatigue performance benefits from the alloy’s good tensile strength and relatively ductile fracture mode, but fatigue limits are influenced by surface finish, residual stresses from forming or welding, and thickness. Thickness effects are pronounced: thinner gauges can be processed to higher effective strengths via cold work, while thick plate yields lower formability and different failure modes under cyclic loading.

Property	O/Annealed	Key Temper (H32)	Notes
Tensile Strength	150–200 MPa	320–380 MPa	Values vary with thickness and exact temper; H32 provides significant uplift over O
Yield Strength	65–110 MPa	260–320 MPa	Yield increases strongly with strain hardening and stabilization
Elongation	20–30%	5–8%	Elongation drops as temper hardening increases; gauge effects apply
Hardness	35–45 HB	80–95 HB	Brinell values indicative; hardness correlates with cold work and temper

Physical Properties

Property	Value	Notes
Density	2.68 g/cm³	Typical of aluminum alloys, used for lightweight design calculations
Melting Range	~570–645 °C	Solidus–liquidus range depends on alloying content and homogenization
Thermal Conductivity	120–140 W/m·K	Lower than pure Al due to Mg in solid solution but still high for heat-transfer applications
Electrical Conductivity	~30–38 %IACS	Reduced compared with pure aluminum; conductivity decreases with cold work
Specific Heat	~0.90 J/g·K	Typical value used in thermal mass and transient heating calculations
Thermal Expansion	23.5–24.5 µm/m·K	Coefficient similar to other Al–Mg alloys; relevant to differential expansion design

5657’s thermal and electrical properties make it attractive for heat-sinking and electrical enclosures where mechanical strength is also required. Thermal conductivity is sufficient for many passive cooling applications, but designers should account for reduced conductivity relative to pure aluminum when specifying cross-sections and fin geometries.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.3–6.0 mm	Strength increases with cold reduction	O, H14, H32	Widely used for body panels, marine topsides and structural skins
Plate	6–200 mm	Lower initial formability, good structural strength	O, H32	Heavy structural components and fabricated structures
Extrusion	Profiles up to 250 mm	Mechanical strength depends on downstream cold work	H111, H32	Complex cross-sections for frames, rails and structural components
Tube	Ø6–300 mm wall 0.5–10 mm	Strength and formability depend on manufacturing	O, H14	Pressure-containing and structural tubing for marine and transport
Bar/Rod	Ø5–150 mm	Good strength in cold-drawn tempers	H111, H14	Fasteners, machined fittings and connector material

Processing route and product form strongly influence the delivered properties of 5657. Rolled sheet and plate typically undergo homogenization, rolling and controlled cooling to establish a workable microstructure, whereas extrusions and forgings rely on billet quality and downstream tempering to control grain structure and strength. Fabrication choices should reflect both part geometry and required mechanical performance.

Equivalent Grades

Standard	Grade	Region	Notes
AA	5657	USA	Wrought Al–Mg alloy as specified for general use in structural applications
EN AW	5xxx (approx.)	Europe	Closest analogs lie within the EN AW-5xxx family; exact number varies with Mg and Mn content
JIS	A5xxx (approx.)	Japan	Equivalent found among JIS Al–Mg wrought alloys with similar Mg levels
GB/T	5xxx (approx.)	China	Chinese standards have comparable 5xxx designations; composition tolerances may differ

Direct cross-references vary by regional standard and exact compositional tolerances; equivalents typically fall into the broader Al–Mg wrought family rather than being one-to-one matches. Differences between standards usually concern impurity limits, guaranteed mechanical properties at specified thicknesses, and permitted surface condition for specific product forms.

Corrosion Resistance

5657 displays good general atmospheric corrosion resistance typical of Al–Mg alloys, developing a stable oxide film that protects the substrate in rural and industrial environments. In marine or chloride-bearing atmospheres, the alloy’s relatively high magnesium content improves pitting resistance compared to 1xxx and 3xxx series alloys, but careful attention to alloy temper, welding practice and surface finish is required to avoid localized corrosion.

Stress-corrosion cracking (SCC) sensitivity for Al–Mg alloys increases with magnesium content and with exposure to tensile stresses in chloride environments; 5657 mitigates this through controlled additions of manganese and chromium which stabilize grain structure and reduce susceptibility. Galvanic interactions are driven by contact with more noble metals such as stainless steel and copper; designers should isolate dissimilar metals or provide sacrificial anodes in marine systems to protect thin sections.

Compared with 6xxx (Al–Mg–Si) alloys, 5657 offers superior seawater corrosion resistance but generally lower peak age-hardening strength; compared with 7xxx (Al–Zn–Mg) alloys it trades ultimate strength for significantly improved corrosion and weldability characteristics. Proper surface treatments, sealants and cathodic protection extend service life in aggressive environments.

Fabrication Properties

Weldability

5657 welds readily using conventional processes such as MIG (GMAW) and TIG (GTAW), with recommended filler alloys in the Al–Mg family (e.g., ER5356 or ER5183) to match strength and corrosion properties. Hot-cracking risk is low provided welding parameters minimize restraint and low-hydrogen practices are used; post-weld HAZ softening is limited because the alloy is non-heat-treatable, although some reduction in local hardness and elevated residual stresses should be expected. For structural applications, weld procedure qualification and appropriate filler selection are essential to ensure joint performance in fatigue and SCC-prone environments.

Machinability

As a ductile Al–Mg alloy, 5657 typically machines with moderate difficulty compared with free-machining alloys; it tends to produce long, continuous chips that require chip control strategies. Carbide tooling with positive rake geometries and sharp edges gives the best balance of surface finish and tool life; cutting speeds are moderate and feeds should be set to avoid built-up edge. Secondary finishing operations such as polishing or chemical deburring are common to meet tight surface-finish requirements that affect fatigue life and corrosion initiation.

Formability

Formability is excellent in the O temper, enabling deep drawing, complex stamping and moderate stretch forming; minimum bend radii are small in annealed material. As H-tempers are introduced, the alloy work-hardens rapidly and springback increases, so designers should allow larger bend radii or select intermediate tempers for forming followed by controlled stabilization. Hydroforming and incremental forming techniques broaden the alloy’s applicability for complex shapes while minimizing local thinning and fracture risk.

Heat Treatment Behavior

5657 is a non-heat-treatable alloy and does not gain strength from solution treatment and artificial aging; instead, mechanical properties are controlled by cold work and by thermomechanical processing. Annealing (O temper) is achieved by heating to appropriate homogenization or recrystallization temperatures followed by controlled cooling to restore ductility for forming operations. Stabilizing heat treatments at modest temperatures can be used to relieve residual stresses and temper the microstructure, producing H22/H32 conditions that provide dimensional stability and resistance to natural aging.

Because the alloy is not subject to precipitation hardening, the common T-series solution/aging cycles (e.g., T6) are not effective and will not produce the sharp increases in strength seen in 2xxx or 6xxx families. Instead, process control emphasizes cold-work fraction, controlled strain paths, and low-temperature stabilizing treatments to set final properties for fabrication and service.

High-Temperature Performance

At elevated temperatures the solid-solution strengthening provided by magnesium weakens as solute mobility increases, so 5657 experiences progressive strength loss above approximately 100–150 °C. For intermittent exposures up to ~200 °C short-term mechanical integrity may be retained depending on loaded condition, but long-term service above 150 °C accelerates softening and recovery processes that reduce yield and fatigue life. Oxidation is minimal compared with ferrous alloys due to the protective alumina layer, but elevated temperatures can promote grain growth and localized microstructural changes that affect post-weld and fatigue behavior.

Designers should avoid operating conditions that combine elevated temperature, tensile stress and chloride exposure since these factors multiply susceptibility to stress-corrosion cracking and accelerated corrosion. Where elevated temperature service is required, alternative alloys with higher temperature stability or protective coatings should be considered.

Applications

Industry	Example Component	Why 5657 Is Used
Automotive	Crash rails, inner body panels	High strength-to-weight, good formability in selected tempers
Marine	Hull plating, deck structures	Improved seawater corrosion resistance and weldability
Aerospace	Secondary structures, fittings	Favorable strength-to-weight and good fatigue behavior for non-primary structures
Electronics	Heat spreaders, chassis	Thermal conductivity balanced with mechanical stiffness for robust enclosures

5657 is frequently specified where a balance of strength, corrosion resistance and fabrication ease is required rather than the absolute maximum strength. Its applicability spans formed sheet components to welded structural assemblies where lifecycle corrosion performance and manufacturability are priorities.

Selection Insights

Choose 5657 when a designer needs a weldable aluminum with higher strength than commercially pure aluminum while retaining good corrosion resistance for marine or structural use. It is valuable when cold forming is required initially and when post-forming stabilization or H-tempers can deliver the needed dimensional stability.

Compared with commercially pure aluminum (1100), 5657 sacrifices some electrical and thermal conductivity and reduced pure-form formability in exchange for substantially higher yield and tensile strength. Compared with common work-hardened alloys such as 3003 or 5052, 5657 typically sits higher in strength and often equals or exceeds corrosion resistance, but may be slightly more costly and less conductive. Compared with heat-treatable alloys like 6061, 5657 will not reach the same peak age-hardened strength but is often preferred where superior seam weldability and marine corrosion resistance outweigh maximum strength.

Closing Summary

5657 remains a practical choice for engineers seeking a non-heat-treatable aluminum that combines strong solid-solution strengthening, reliable weldability and robust corrosion performance in chloride-containing environments. Its balance of mechanical and fabrication properties makes it suitable for a wide range of structural, marine and transport applications where lifecycle durability and manufacturability are key design drivers.