Aluminum 4035: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

4035 is a member of the 4xxx series of aluminum alloys, a family characterized by silicon as the principal alloying element. This classification places 4035 among alloys developed for improved fluidity, wear resistance in castings and filler/welding applications, and moderate strength through solid-solution and dispersoid effects rather than classical precipitation hardening.

The major alloying elements in 4035 are silicon and controlled additions of magnesium, with minor amounts of iron, manganese, titanium and trace elements to control grain structure and casting/welding behavior. The combination yields a material that is not primarily age‑hardening; its strengthening mechanisms are dominated by solution/solid‑state strengthening from Si, fine dispersoids formed during thermal cycles, and work‑hardening for wrought tempers.

Key traits of 4035 include moderate static strength, good fluidity and wettability for welding and brazing, reliable corrosion resistance in atmospheric and mildly marine environments, and good formability in annealed or lightly work‑hardened conditions. Its weldability is a strong point, particularly where silicon additions aid filler flow and reduce hot‑cracking tendency, making 4035 attractive in automotive, consumer appliance, and certain structural applications where a balance of formability, corrosion resistance and weld performance is required.

Engineers often choose 4035 over purer alloys when enhanced weldability and joint integrity are priorities without resorting to softer, lower‑strength base metals. It is selected over some 6xxx alloys when weld filler compatibility and reduced requirement for post‑weld heat treatment are desired. The alloy’s combination of machinability, acceptable strength, and corrosion resistance make it a pragmatic choice for fabricated assemblies and welded structures.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High	Excellent	Excellent	Fully annealed, maximum ductility and formability
H14	Moderate-High	Low-Moderate	Good	Excellent	Strain‑hardened to a quarter hard, common for sheet goods
H18	Moderate	Moderate	Good	Excellent	Stabilized and partially stress‑relieved, used where some springback control is needed
H24	Moderate	Moderate	Good	Excellent	Strain‑relieved after work hardening, balances strength and ductility
T4 (limited)	Limited increase	Moderate	Good	Good	Natural or partial solutionized; not commonly used for 4xxx family
T5/T6	Not typical	N/A	Reduced	Reduced	Artificial aging to peak hardness is generally not effective for 4xxx alloys

The temper of 4035 strongly controls the tradeoff between formability and strength. Annealed (O) tempers provide the best drawability and bendability for deep‑forming operations, while H‑tempers increase strength at the expense of elongation and bend radius.

Weldability remains good across most temper conditions because silicon reduces the solidification range and susceptibility to hot cracking; however, strain‑hardened tempers can exhibit increased springback and require more force for forming after welding.

Chemical Composition

Element	% Range	Notes
Si	5.5–8.5	Principal alloying element; improves fluidity, reduces melting range and increases wear resistance
Fe	0.3–0.8	Residual impurity; forms intermetallics that affect ductility and high‑temperature stability
Mn	0.1–0.6	Grain structure modifier; improves strength and reduces hot‑shortness
Mg	0.3–0.9	Small additions promote limited Mg2Si precipitation and boost strength marginally
Cu	≤0.2	Kept low to maintain corrosion resistance and reduce tendency for galvanic activity
Zn	≤0.25	Low; large additions not typical for 4xxx family
Cr	≤0.1	Controls grain growth and improves toughness in some tempers
Ti	≤0.2	Grain refiner for castings and extrusions
Others (each)	≤0.05	Trace elements controlled to maintain weldability and mechanical consistency

Silicon is the dominant performance driver: it reduces the liquidus‑solidus gap, enhances melt flow and wetting for welding and casting, and contributes to solid solution strengthening. Magnesium at controlled levels can form fine Mg2Si dispersoids during thermal exposure, slightly increasing strength without enabling full heat‑treatability. Iron and manganese primarily influence grain and intermetallic formation, which in turn affect toughness and formability.

Mechanical Properties

In service, 4035 exhibits moderate tensile behavior with a relatively wide range depending on temper, section thickness and processing history. Annealed material shows low yield and modest tensile strength with high elongation, while cold‑worked H‑tempers raise yield and tensile strength with corresponding reductions in ductility. Hardness correlates with the degree of cold work; annealed plates are soft and easy to form, while H14/H24 sheet types reach higher Brinell and Rockwell values useful for moderate structural loads.

Fatigue behavior of 4035 is typical for silicon‑rich alloys: fatigue strength is serviceable for cyclic loads when stress concentrations are minimized, and surface finish and residual stresses from forming/welding have substantial influence. Thickness effects are notable because larger cross sections retain more as‑cast or as‑extruded microstructural heterogeneity; thin gauges are more uniform and respond more predictably to cold working and welding. Weld heat‑affected zones may show localized softening or changes in ductility, but bulk properties remain dominated by composition and temper.

Processing route and post‑forming strain history largely determine final mechanical performance. Designers should expect lower peak strength than many 6xxx heat‑treatable alloys but better weld joint integrity and comparable corrosion resistance to 5xxx alloys in many environments.

Property	O/Annealed	Key Temper (H14/H24)	Notes
Tensile Strength	110–150 MPa	200–260 MPa	Range depends on cold work and thickness; values indicative for wrought product
Yield Strength	55–90 MPa	120–180 MPa	Yield increases markedly with strain hardening
Elongation	18–28%	6–12%	Ductility decreases as strength rises; thinner gauges show higher elongation
Hardness (HB)	30–50 HB	60–95 HB	Hardness correlates with temper; reported ranges depend on manufacturing

Physical Properties

Property	Value	Notes
Density	2.66–2.70 g/cm³	Typical for silicon‑alloyed aluminum; slightly lower than steel for weight savings
Melting Range	577–640 °C	Eutectic shift from silicon lowers liquidus relative to pure Al and gives a fluid melting range
Thermal Conductivity	~140–170 W/m·K	Reduced vs pure Al due to alloying; still good for heat‑dissipation applications
Electrical Conductivity	~25–35 %IACS	Alloying with Si and Mg lowers conductivity compared with commercial‑pure Al
Specific Heat	~0.88–0.90 J/g·K	Typical for aluminum alloys in this category
Thermal Expansion	~23–24 µm/m·K	Coefficient of thermal expansion similar to other wrought aluminum alloys

The presence of silicon and other alloying elements reduces thermal and electrical conductivity compared to commercially pure aluminum. Nevertheless, 4035 retains favorable thermal performance for heat‑spreaders and components where moderate conductivity and lower thermal expansion are required.

Designers must balance reduced conductivity with advantages in castability, weldability and mechanical stability. The melting range and lower liquidus promote reliable fusion and wetting in welding and brazing operations.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.3–6.0 mm	Uniform, responsive to cold work	O, H14, H18, H24	Widely used for panels and formed components
Plate	>6.0–50 mm	Slightly lower strength at same nominal temper due to residual casting/rolling effects	O, H32	Plate requires heavier forming; used for structural segments
Extrusion	Wall thickness 1–20 mm; profiles variable	Strength varies with profile and cooling rate	O, H14	Extruded profiles leverage silicon for improved die filling and surface finish
Tube	Ø10–400 mm	Typical tube strengths match sheet/plate tempers	O, H14	Seamless or welded tubes available; used in hydraulic and structural applications
Bar/Rod	Ø3–100 mm	Similar temper behavior to extrusions	O, H14	Used for machined components and fasteners where weldability is a plus

Forming and processing routes significantly influence the mechanical response and surface condition of 4035. Sheets and extrusions can be cold‑worked to increase strength, whereas plate and thicker sections may require preheating or heavier forming equipment. Welding is commonly performed on these product forms without aggressive post‑weld treatments, though designers should account for HAZ effects in load‑bearing joints.

Equivalent Grades

Standard	Grade	Region	Notes
AA	4035	USA	American Aluminum Association designation for wrought 4xxx series composition
EN AW	4035	Europe	EN standard mirrors AA chemistry but tolerances and tempers may differ slightly
JIS	A4035	Japan	Japanese designation; chemistry compatible but manufacturing practices and impurity limits differ
GB/T	4035	China	Chinese standard with similar nominal composition but differing control on trace elements

Direct one‑to‑one equivalence across standards exists in nominal composition, but inspection limits, impurity controls and permitted microstructural tolerances vary. European and Japanese standards commonly require tighter control of iron and copper to ensure consistent weldability and corrosion resistance. Buyers should always request the relevant material certificate and cross‑reference temper and mechanical property requirements for critical applications.

Corrosion Resistance

4035 offers very good atmospheric corrosion resistance, in part due to the silicon content and low copper levels which reduce galvanic activity in air and mildly industrial environments. In rural and urban atmospheres it performs comparably to many 5xxx and 6xxx alloys, maintaining passive oxide films that protect surfaces under typical service temperatures.

In marine or chloride‑bearing environments, 4035 exhibits acceptable performance for structural components above the splash line, but like most aluminum alloys it is susceptible to pitting and crevice corrosion in stagnant saltwater or under deposits. Protective coatings, anodizing or cathodic protection are recommended where prolonged immersion or concentrated chlorides are expected.

Stress corrosion cracking (SCC) susceptibility is low compared with high‑strength 7xxx series alloys, but not zero; SCC risk increases with elevated tensile stresses, aggressive halide exposure, and certain manufacturing residual stresses. When in electrical contact with more noble metals, galvanic interactions can accelerate corrosion of 4035 unless isolating measures or compatible fasteners are used.

Compared with 5xxx magnesium alloys, 4035 generally exhibits similar or slightly better localized corrosion resistance due to lower Mg and Cu contents. Compared with 6xxx alloys, 4035 is often preferred when weldability and reduced need for post‑weld tempering are priorities, despite slightly lower peak strength.

Fabrication Properties

Weldability

4035 is formulated for excellent fusion welding and brazing performance; silicon reduces the solidification temperature range and minimizes hot‑cracking tendency. It is well suited to TIG, MIG (GMAW), and resistance welding with stable bead profiles and good wetting of base material. Recommended filler metals mirror the base alloy chemistry (Si‑bearing aluminum fillers) to preserve ductility and corrosion resistance; filler selections such as Al‑Si fillers are commonly used. Care is required to manage heat input to prevent excessive HAZ softening and to control distortion in thin gauges.

Machinability

Machinability of 4035 is generally good and better than many high‑strength aluminum alloys due to its moderate strength and silicon content which provides stable chip formation. Standard carbide tooling with appropriate coatings (TiAlN, TiN) and moderately high cutting speeds are recommended to optimize tool life and surface finish. Chip control is straightforward but can be affected by Mg and Fe intermetallics in thicker sections; finishing passes reduce burring and improve fatigue life at notches. Coolant application and rigid fixturing improve dimensional control during high‑material‑removal operations.

Formability

Formability in annealed 4035 is excellent, enabling deep drawing, bending and complex stampings with relatively small minimum bend radii compared with harder tempers. Cold work (H‑tempers) increases strength but requires larger bend radii and springback compensation during tooling design. For severe forming or stretch‑forming, use O temper or apply intermediate anneals to restore ductility; warm forming can be employed for thick sections to reduce required forces. Tooling surfaces should be clean and lubricated to prevent galling, particularly when forming thin gauges in H‑tempers.

Heat Treatment Behavior

4035 is not a classical heat‑treatable (T6‑type) alloy; it does not respond to standard solution treatment and artificial aging sequences with the same magnitude of property improvement as 6xxx (Mg‑Si) or 7xxx (Zn‑Mg) alloys. Attempts at solution and age cycles yield limited additional strengthening because silicon in 4xxx alloys primarily forms silicon phases rather than a continuous age‑hardening precipitate structure.

Annealing effectively softens 4035 and restores ductility after cold working. Typical annealing is performed at temperatures in the 350–415 °C range with controlled cooling to minimize grain growth and retain good surface finish. Work‑hardening (strain hardening) is the principal hardening route for wrought tempers; manufacturers control final temper through calibrated cold reduction and stress relief processes rather than precipitation hardening.

When post‑weld properties are critical, designers rely on mechanical design and filler selection to achieve joint integrity rather than expecting significant strength recovery through heat treatment. For applications demanding higher peak strengths than 4035 can provide, substitution with heat‑treatable alloys should be considered.

High-Temperature Performance

4035 exhibits gradual strength loss with increasing temperature, with significant softening observed above approximately 150–200 °C. For sustained structural service, recommended maximum continuous use temperatures are typically below 125 °C to avoid permanent loss of mechanical properties and dimensional stability. Elevated temperatures also accelerate coarsening of dispersoids and intermetallic particles, which can reduce fatigue life and creep resistance.

Oxidation at service temperatures is limited by the protective Al2O3 film; however, prolonged exposure at higher temperatures can lead to scaling and changes in surface chemistry that affect subsequent welding or adhesive bonding. Heat‑affected zones from welding may exhibit local microstructural changes, but overall oxidation behavior is less severe than that of ferrous alloys at comparable temperatures. Designers should perform application‑specific testing for high‑temperature cyclic loading and long‑term exposures.

Applications

Industry	Example Component	Why 4035 Is Used
Automotive	Body panels, welded assemblies	Good formability and weldability; improved joint quality vs some other alloys
Marine	Bulkheads, brackets above splash line	Corrosion resistance and weldability for fabricated components
Aerospace	Secondary fittings and fairings	Favorable strength‑to‑weight and weld performance for non‑critical structures
Electronics	Heat spreaders, housings	Adequate thermal conductivity and easy fabrication for enclosures
Consumer Appliances	Washer/dryer panels, heat exchangers	Good surface finish, formability and cost‑effective fabrication

4035 is particularly well suited for applications where welded assemblies require reliable wetting and minimal hot‑cracking, and where post‑weld heat treatment is undesirable or impractical. Its balance of mechanical, thermal and fabrication properties makes it a versatile option for many mid‑weight structural and fabricative roles.

Selection Insights

Use 4035 when weldability and ease of fabrication are central design drivers and when a balance of moderate strength with good corrosion resistance is required. It is a pragmatic choice for welded panels, extruded profiles and tubing where filler compatibility and joint integrity are priorities.

Compared with commercially pure aluminum (1100), 4035 trades some electrical and thermal conductivity and slightly reduced formability for significantly higher strength and better wear and weld behavior. Compared with common work‑hardened alloys such as 3003 or 5052, 4035 typically delivers comparable corrosion resistance with improved weldability and slightly higher achievable strength via cold work. Compared with heat‑treatable alloys such as 6061 or 6063, 4035 will not reach the same peak strengths, but is preferred where welding without subsequent aging or where superior weld puddle fluidity is required.

For buyers, select 4035 when cost, availability, and fabrication speed (fewer post‑weld treatments) outweigh the need for maximum heat‑treated strength. Specify temper and mill certificates aligned with forming and welding plans to ensure predictable in‑service performance.

Closing Summary

4035 remains relevant as a silicon‑enriched 4xxx alloy that combines good weldability, solid formability in annealed states, and reliable corrosion performance for many fabricated applications. Its pragmatic balance of properties makes it a strong choice where fabrication efficiency and joint integrity are more important than the highest available heat‑treatable strengths.