Aluminum 4017: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

4017 is a member of the 4xxx series of aluminum alloys, a family normally characterized by elevated silicon levels that influence melting behavior and welding characteristics. The 4xxx classification signals silicon as the principal alloying element, with 4017 developed to balance formability, weldability and moderate strength for structural and joining applications.

Major alloying elements in 4017 include silicon as the dominant alloyant, with controlled additions of magnesium and manganese and small controlled amounts of iron and titanium as residuals. Strength in 4017 is generated primarily through solid-solution strengthening by silicon and cold work (strain hardening); it is treated as essentially non-heat-treatable for strength gains, although minor artificial aging can affect microstructural stability in specific tempers.

Key traits of 4017 are moderate tensile and yield strength relative to pure aluminum, improved weldability and brazing behavior because of silicon, and good general corrosion resistance in atmospheric and mildly marine environments. Formability in annealed tempers is strong, while some tempering and cold work raise strength at the expense of ductility.

Typical industries using 4017 include automotive body and chassis components, welded and brazed assemblies, architectural extrusions, and general fabrication where a combination of formability and weldability is required. 4017 is chosen over some other alloys when improved weld-filler compatibility, reduced hot-cracking susceptibility and a balance of strength and formability are needed without the cost or manufacturing complexity of high-strength heat-treatable alloys.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High (20–35%)	Excellent	Excellent	Fully annealed, maximum ductility for forming
H12	Low-Medium	Moderate (10–20%)	Good	Excellent	Partial strain hardening, limited forming
H14	Medium	Moderate (8–15%)	Fair-Good	Excellent	Single-step strain hardening for moderate strength
H22	Medium	Moderate (8–15%)	Good	Excellent	Strain-hardened and stabilized by low-level thermal exposure
H24	Medium-High	Lower (6–12%)	Fair	Excellent	Strain hardened plus some natural aging/stabilization
T4	N/A / Limited	N/A	Moderate	Good	Solution-treated and naturally aged; rarely used for 4xxx alloys
T5	Limited	Moderate	Fair-Good	Good	Cooled from elevated temperature and artificially aged; limited benefit
T6	Not typical	N/A	Poor	Good	Generally not applicable; 4xxx alloys are not reliably heat-treatable for high strength

Temper significantly modifies 4017 performance by trading ductility for strength via strain hardening and stabilization processes. Annealed (O) condition offers the best formability for deep drawing and bending, while H-series tempers provide stepwise increases in yield and tensile strength with corresponding losses in elongation.

Selection of a working temper must consider downstream joining operations, as cold work can influence residual stress and distortion during welding, and some stabilized tempers reduce the extent of softening in the heat-affected zone.

Chemical Composition

Element	% Range	Notes
Si	4.0–6.0	Primary alloyant; lowers melting range, improves weldability and brazing; contributes to strength
Fe	0.2–0.8	Impurity element; forms intermetallics that affect toughness and surface finish
Mn	0.2–0.8	Grain structure control and some strengthening via dispersoids
Mg	0.2–0.8	Small additions enhance strength via solid solution and minor precipitates when balanced with Si
Cu	≤0.1	Kept low to preserve corrosion resistance and to avoid excessive strengthening that reduces ductility
Zn	≤0.1	Low content to avoid sensitization and galvanic concerns
Cr	≤0.1	Trace additions for grain control and to stabilize microstructure
Ti	≤0.15	Grain refiner, added in small amounts to control cast and wrought grain size
Others	Balance Al; impurities ≤0.15 each	Includes residuals and trace elements controlled for performance consistency

The chemical balance in 4017 places silicon as the dominant strengthening and processing element, with modest magnesium and manganese to tune mechanical behavior and microstructure. Silicon reduces melt viscosity and improves flow in brazing and welding, while Mg and Mn provide modest additional strength and control of recrystallization. Tight control of iron and copper is important to maintain toughness and corrosion resistance.

Mechanical Properties

Tensile behavior in 4017 is characterized by a relatively flat strain-hardening response in wrought tempers, with annealed material showing high elongation and lower yield and ultimate tensile strengths. Yield-to-tensile ratios tend to be moderate, meaning some plasticity before permanent deformation but less than very soft commercial purity aluminum. Thickness and processing history influence measured strengths, with heavily cold-worked sheets exhibiting marked increases in yield and tensile values.

Elongation in O tempers typically exceeds 20% and allows extensive forming, while H-series tempers reduce elongation toward the low teens. Hardness correlates with temper and cold work, with Brinell or Vickers hardness values increasing predictably with H-number while annealed material remains relatively soft. Fatigue performance is acceptable for general fabrication, but surface condition, welds and residual stresses are primary influencers of fatigue life.

Thickness effects are significant; thin gauges attain higher work-hardening rates during forming and may show higher tensile strengths in strained tempers due to through-thickness cold work. Conversely, thicker plate and extrusions are less responsive to stretch-forming and may rely more on alloy chemistry and precipitation to achieve strength.

Property	O/Annealed	Key Temper (e.g., H14)	Notes
Tensile Strength	120–170 MPa	180–260 MPa	Values vary with gauge and degree of cold work; typical lab values shown
Yield Strength	50–100 MPa	120–200 MPa	Yield increases strongly with strain hardening
Elongation	20–35%	8–15%	Ductility reduced in strain-hardened tempers
Hardness	30–55 HB	55–95 HB	Hardness tracks cold work; annealed alloy is soft and easily machined/formable

Physical Properties

Property	Value	Notes
Density	2.68–2.71 g/cm³	Typical lightweight aluminum density; varies slightly with Si content
Melting Range	~575–640 °C	Eutectic and solidus-liquidus range widened by silicon additions
Thermal Conductivity	120–160 W/m·K	Lower than pure Al but still high; Si reduces conductivity relative to Al-1100
Electrical Conductivity	~30–45 % IACS	Reduced from pure Al because of alloying additions
Specific Heat	~0.88–0.90 J/g·K	Comparable to other Al alloys
Thermal Expansion	22–24 µm/m·K (20–100 °C)	Typical aluminium expansion; consider for joined dissimilar materials

The physical properties of 4017 make it attractive where low weight and thermal management are required, while its silicon content moderates melting characteristics for joining processes. Thermal conductivity is still adequate for heat-sinking applications but is reduced versus very pure aluminium grades; designers should account for this in thermal analyses.

Electrical conductivity reduction means 4017 is not a preferred choice for high-performance conductors, but it remains suitable for structural parts that must also conduct electricity at moderate levels or be welded using standard aluminum practices.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.3–6.0 mm	Thin gauge responds well to cold work	O, H14, H24	Used for formed panels, welded assemblies, and cladding
Plate	6–50 mm	Thicker sections show lower strain hardening	O, H22	Used for structural welded components and machined parts
Extrusion	Up to large profiles	Strength depends on extrusion ratio and cooling	O, H14	Profiles for frames, tracks, and welded assemblies
Tube	1–10 mm wall	Behavior depends on forming (seam-welded or seamless)	O, H12	Good for welded hydraulic or structural tubing
Bar/Rod	5–50 mm	Limited strain hardening in cross-section	O, H12	Used for machined components and fittings

Processing differences between product forms stem from section thickness and cooling rates; thinner sections harden more readily by cold work while thicker extrusions and plates require mechanical or thermal stabilization to achieve desired properties. Extruded sections can be produced with tailored profiles and often receive light heat treatments or stabilization cycles to control residual stresses and dimensional stability.

Application choices follow form: sheet for stamped and welded panels, extrusions for structural frames, and plate or bar for machined components where bulk properties and stiffness are primary concerns.

Equivalent Grades

Standard	Grade	Region	Notes
AA	4017	USA	Designation within Aluminum Association numbering; chemistry controlled for 4xxx family traits
EN AW	4xxx series equivalent (e.g., EN AW-4043)	Europe	Similar Si-based alloys available; direct equivalence requires chemistry verification
JIS	A4xxx (e.g., A4043)	Japan	Local standards use similar composition windows for welding/brazing alloys
GB/T	4xxx-series equivalent	China	Chinese standards have analogous Si-rich wrought alloys; exact grade mapping required

Cross-references are approximate because national standards occasionally specify differing maximum impurities and tolerance windows that shift mechanical behavior. Engineers should cross-check certificate chemistries and measured properties rather than relying solely on designation numbers when substituting alloys across standards and regions.

Small differences in allowed impurities and trace elements (e.g., Fe, Cu) can alter fatigue, surface finish and weldability, so qualification testing or supply chain audits are recommended for critical applications.

Corrosion Resistance

4017 exhibits good general atmospheric corrosion resistance, owing to the formation of a stable aluminum oxide film and the relatively low content of copper and zinc which can accelerate localized corrosion. In typical outdoor and industrial atmospheres the alloy performs well, with corrosion rates comparable to other silicon-bearing aluminum alloys rather than to magnesium-rich alloys that are more susceptible to pitting.

Marine exposure presents an elevated risk of localized attack if chloride-bearing deposits persist on the surface; however, 4017 resists uniform corrosion well and often performs adequately in splash-zone and coastal applications when protected by coatings or anodizing. Crevice and under-deposit corrosion can be an issue in welded assemblies where flux residues or contaminants remain.

Stress corrosion cracking is not a principal failure mode for the 4xxx family; 4017 is less susceptible to SCC than certain highly stressed 7xxx magnesium-containing alloys. Galvanic interactions should be considered when 4017 is mated to more noble alloys such as stainless steels or copper; anodic protection or insulating barriers are recommended for mixed-metal joints to avoid accelerated corrosion of the aluminum component.

Compared with 5xxx magnesium-bearing alloys, 4017 trades some sacrificial resistance for better weldability and lower susceptibility to post-weld exfoliation, while compared with 6xxx alloys its corrosion performance is competitive but depends strongly on surface finish and heat-treatment history.

Fabrication Properties

Weldability

4017 is highly weldable by common fusion processes like TIG and MIG because silicon reduces hot-cracking tendency and improves flow of the weld pool. Recommended filler materials are silicon-bearing filler alloys (for example Al-Si fillers similar to EN AW-4043) to ensure metallurgical compatibility and reduce porosity and cracking risk during fusion welding. Heat-affected zone softening is modest compared with heat-treatable alloys, but cold-worked areas can lose some strengthening when welded or post-weld thermally exposed.

Machinability

Machinability of 4017 is moderate to good; silicon content tends to promote predictable chip formation and supports higher cutting speeds than very soft alloys, while still allowing fine surface finish achievement. Carbide tooling with positive rake angles is recommended, and coolant or mist lubrication improves tool life and surface quality. Chip control is influenced by section thickness and temper; heavier Si may produce more abrasive behavior, so tool selection should account for abrasive wear.

Formability

Formability in the annealed O condition is excellent, enabling deep drawing, bending and stretch forming with relatively large bend radii. Recommended minimum bend radii are typically 1–3 times material thickness for common forming operations in O temper, increasing for H-series tempers. Cold-work response is favorable and predictable, enabling incremental strengthening through forming, but springback must be considered for design and tooling to achieve dimensional targets.

Heat Treatment Behavior

As a primarily non-heat-treatable alloy, 4017 does not respond to conventional solution-treatment plus artificial aging routes the way 6xxx or 7xxx series alloys do. Attempts to apply T6-style heat treatment deliver limited strengthening because the Si content and Mg:Si balance do not favor substantial Mg2Si precipitation hardening.

Work hardening is the principal route to raise strength in 4017; controlled cold work followed by stabilization or mild overaging (H2x–H3x series) is used to lock in properties and minimize natural aging effects. Full annealing (O) returns the alloy to its softest, most ductile state for forming operations, and stress-relief anneals are used to reduce residual stresses from forming or welding. For specialized service conditions controlled artificial aging (T5/T4) can be used to stabilize microstructures but yields only modest incremental strength.

Process control during thermal cycles—welding, brazing, or heat entering fabrication steps—is important to limit coarsening of silicon particles and to maintain surface quality and corrosion resistance.

High-Temperature Performance

Elevated temperature reduces the strength of 4017 significantly compared with room temperature values; service temperature limits are typically set conservatively in the 100–150 °C range for sustained load-bearing applications. Above these temperatures silicon-aluminum intermetallics and dispersoids can coarsen, causing reductions in yield and fatigue strength.

Oxidation of aluminum is self-limiting, so scale formation is minimal compared with ferrous alloys, but prolonged exposure at high temperatures can promote surface roughness and embrittlement in fine-featured parts. The heat-affected zone adjacent to welds is susceptible to microstructural changes at elevated temperatures that may reduce local toughness and fatigue resistance.

For intermittent elevated temperature excursions, 4017 can be used when allowance is made for strength degradation and potential dimensional changes; engineering safety factors and thermal stabilization steps should be incorporated for high-temperature service.

Applications

Industry	Example Component	Why 4017 Is Used
Automotive	Outer body panels, welded subframes	Good formability, weldability and moderate strength at low mass
Marine	Structural brackets, non-critical frames	Balanced corrosion resistance and weldability in coastal environments
Aerospace	Secondary fittings, interior structural members	Good strength-to-weight and compatibility with welding/brazing joining
Electronics	Chassis and heat spreaders	Good thermal conductivity and ease of fabrication with controlled surface finish

4017 is commonly deployed where a combination of welded fabrication, forming and reasonable mechanical strength are required without the complexity of heat-treatable alloys. Its use in secondary structural parts and fabricated assemblies leverages its balanced properties and manufacturing friendliness.

Selection Insights

4017 is a practical choice when engineers need superior weldability and brazing compatibility alongside reasonable formability and strength. It is particularly well-suited where joining operations dominate fabrication and where large-scale forming or stamping in annealed tempers is required.

Compared with commercially pure aluminum (e.g., 1100), 4017 trades some electrical conductivity and ultimate formability for substantially higher strength and improved resistance to hot-cracking in welds. Versus common work-hardened alloys like 3003 or 5052, 4017 typically offers improved weldability and slightly better strength for welded or brazed assemblies while maintaining competitive corrosion resistance. Compared with heat-treatable alloys such as 6061 or 6063, 4017 will not reach the same peak strengths but is preferred when welding-driven fabrication, lower susceptibility to HAZ softening and simpler processing are higher priorities than maximum strength.

Consider cost and availability constraints: 4017 is frequently available in sheet and extrusion inventories for fabrication shops, but substitution should always be validated by checking supplier chemistry and property test data against application requirements.

Closing Summary

4017 remains relevant as a silicon-bearing wrought aluminum alloy that delivers a pragmatic balance of weldability, formability and moderate strength for fabrication-heavy applications. Its material chemistry and processing flexibility make it a durable choice where joining operations, manufacturability and corrosion performance must be balanced to meet engineering and production demands.