Aluminum Grades for Extrusions

A practical, vendor-neutral guide to picking the alloy and temper that actually fit your part — not just the strongest one.

Choosing an aluminum extrusion alloy is a balancing act. Strength and extrudability pull in opposite directions: the harder you push an alloy for strength, the harder it is to push through a die — and the more you tend to give up in finish, corrosion resistance, and cost. By the end of this guide you should be able to narrow any custom extrusion to the right alloy family, pick between the common 6000-series grades, and match a temper to the part you're actually building.

New to the process? Start with what aluminum extrusion is →, then come back here.

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Why the 6000-Series Dominates Extrusion

Every alloy choice trades off three things that matter for an extruded part:

• Strength — how much load the section carries.
• Extrudability — how easily and quickly the alloy flows through a die into thin walls and complex shapes, and how much die life and surface quality you get along the way.
• Finish & corrosion resistance — how cleanly it anodizes (an electrochemical surface treatment that builds a hard oxide layer) or paints, and how it holds up in the field.

These three pull against each other. Add the alloying elements that build strength — copper, zinc, magnesium in higher amounts — and the metal gets harder to extrude, often anodizes less uniformly, and can lose corrosion resistance. That tradeoff is the whole story of alloy selection.

Here's roughly where each aluminum series sits on the spectrum, from easiest-to-extrude/lowest-strength to hardest-to-extrude/highest-strength:

Series	Main alloying element	Strength	Extrudability	Typical role in extrusion
1xxx	Pure aluminum	Lowest	Excellent	Electrical, chemical; rarely structural
3xxx	Manganese	Low	Very good	Sheet-heavy; limited extrusion
5xxx	Magnesium	Moderate	Fair–poor	Marine sheet/plate; hard to extrude well
6xxx	Magnesium + silicon	Moderate–high	Very good–excellent	The workhorse of custom extrusion
7xxx	Zinc (+ magnesium, copper)	Very high	Poor	Aerospace; rarely extruded for general use
2xxx	Copper	Very high	Poor	Aerospace; poor corrosion/weldability

The 6000-series (6xxx, an aluminum-magnesium-silicon family) lands in the sweet spot: enough strength for the large majority of structural and cosmetic parts, with the extrudability, finishing, weldability, and corrosion resistance to make those parts practical and affordable. That's why it accounts for the large majority of custom extrusion work. The rest of this guide focuses there, then explains where the high-strength alloys do and don't fit.

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The Core Extrusion Alloys, Head to Head

This is the reference. The table below compares the 6xxx alloys you'll actually specify, followed by a plain-English "choose this when…" line for each. Directional comparisons (which alloy is stronger, finishes better, extrudes easier) are well established; for exact mechanical properties, always work from the Aluminum Design Manual or your supplier's datasheet for the specific alloy and temper you're specifying.

Alloy	Strength	Corrosion resistance	Extrudability	Finish / anodizing	Weldability	Conductivity	Typical temper	Typical uses
6063	Moderate	Very good (low copper)	Best of the group	Best of the group	Good	Good	T5, T6	Trim, frames, railings, heat-sink fins, anything visible/anodized
6061	Higher	Good	Good	Fair (can streak)	Good	Good	T6, T4	Structural members, machined parts, transportation
6005 / 6005A	Near-6061	Very good	Very good	Good	Good	Good	T5, T6	Complex/thin structural sections, trailer & RV rails
6082	Highest of common 6xxx	Very good	Harder than 6063/6061	Good	Good	Good	T6	Structural (more common in Europe / EN standard)
6101	Moderate	Good	Very good	Good	Good	Highest of the group	T6, T61, T64	Bus bar, electrical conductors

Two more worth knowing by name: 6060 behaves much like a softer, very-easy-to-extrude cousin of 6063 (common in Europe for fine architectural detail), and 6105 sits near 6005/6061 on strength and shows up in transportation profiles.

6063 — the architectural alloy

Moderate strength, very good corrosion resistance thanks to low copper content, and the best extrudability and best anodized finish in the group. It fills thin walls and complex, detailed cross-sections cleanly and takes a uniform, cosmetic anodized surface.

Choose 6063 when the part is visible, anodized or color-matched, thin-walled, or built for heat dissipation (tall, fine fins) rather than heavy structural load.

For a deeper head-to-head with 6061, see our dedicated comparison: 6063 vs 6061 →.

6061 — the do-everything structural alloy

Higher strength than 6063, good corrosion resistance, and good machinability — the default when a part has to carry real load or get machined after extrusion. The trade-off is cosmetic: its anodized finish is less uniform than 6063's and can streak, so it's a weaker choice where appearance is matched across multiple pieces.

Choose 6061 when the part is load-bearing or heavily machined and finish uniformity is secondary.

6005 / 6005A — the versatile middle

6005 and 6005A approach 6061's strength while extruding more easily, which makes them well suited to complex or thin structural sections that would be slow or marginal in 6061. 6005A adds small amounts of chromium and manganese that improve toughness and resistance to stress-corrosion cracking. It's common in trailer and RV rails and other structural profiles that need both strength and a clean extrusion.

Choose 6005A when you need close-to-6061 strength in a complex or thin section, or in corrosion-prone structural parts.

6082 — highest strength of the common 6xxx

The strongest of the everyday 6xxx alloys, with very good corrosion resistance, but harder to extrude than 6063 or 6061. It's specified more often in Europe (under the EN standard) than in North America, where 6061 typically fills the same role.

Choose 6082 when you need maximum 6xxx strength, the section isn't highly complex, and the standard or supply base favors it.

6101 — the conductor alloy

6101 trades some mechanical strength for higher electrical conductivity (often reported in %IACS, a scale where pure annealed copper is 100%). It's the standard choice for bus bar and other current-carrying extrusions.

Choose 6101 when the part's job is to carry current, not load.

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Where 7075 and the 2000-Series Fit — and Why They're Rarely Extruded

It's tempting to reach for the strongest aluminum available. For extrusions, that's usually the wrong move, and it's worth understanding why.

7075 is among the strongest common aluminum alloys, but it carries real penalties for extruded parts: it isn't reliably fusion-weldable, its corrosion resistance is lower than the 6xxx alloys, it costs significantly more, and it extrudes slowly and with difficulty into anything but simple shapes. It earns its place in aerospace and defense parts that are machined or bolted — not in general custom extrusions.

2024 (a 2xxx, copper-based alloy) is similar in spirit: high strength, but poor corrosion resistance and poor weldability. Like 7075, it lives in aerospace and specialized machined-or-fastened applications rather than everyday extruded profiles.

The takeaway reinforces the core tradeoff: these alloys buy strength by giving up the extrudability, weldability, corrosion resistance, and cost that make a custom extrusion practical. Unless your part specifically requires that strength and is designed to be machined or fastened rather than welded, a 6xxx alloy will almost always serve you better.

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Tempers Explained: T5 vs T6 (and the Others)

A temper describes the thermal and mechanical treatment that sets an alloy's final strength and stability. The same alloy in two tempers behaves differently, so the temper is part of the spec — not an afterthought. The two you'll choose between most often are T5 and T6.

T5 — cooled from the press, then artificially aged. The profile is quenched as it exits the extrusion press (using its own process heat) and then aged in an oven. T5 is less expensive, carries lower internal stress, and holds dimensions well — which makes it a strong fit for thin or complex shapes that would distort under a harder treatment. The trade-off is moderate strength.

T6 — solution heat-treated, quenched, then aged. The profile is reheated, held, rapidly quenched, and aged for maximum strength. That extra strength is real, but the quench can introduce distortion and internal stress, especially in thin walls or complex cross-sections.

A few others you may see:

• T4 — solution heat-treated and naturally aged; formable, lower strength than T6, sometimes chosen when the part is bent or worked after extrusion.
• T52 — stress-relieved for improved dimensional stability.
• T1 — cooled from the press and naturally aged; a softer, as-extruded condition.

The message: T6 isn't automatically "better." For a thin, detailed, or tightly toleranced section, T5 often delivers a more stable, lower-cost part that still meets the load. Match the temper to the part.

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How to Actually Choose: The Questions That Drive the Decision

Alloy and temper selection comes down to a handful of practical questions. Run your part through these before you lock anything in.

• Is the part structural or cosmetic? Load-bearing leans toward 6061 or 6005A. Visible or anodized leans toward 6063.
• Will it be anodized or color-matched across multiple pieces? Favor 6063 for uniform finish; 6061 can streak when anodized.
• How thin-walled or complex is the cross-section? The thinner and more intricate the profile, the more it favors 6063, then 6005A.
• Will it be welded? All 6xxx alloys weld reasonably well; avoid 7075. Design for strength loss in the heat-affected zone (HAZ) — the band of metal beside a weld that's softened by welding heat.
• What's the corrosion environment? Marine, chloride, or wash-down service favors the low-copper alloys, 6063 and 6005A.
• T5 or T6? Decide whether you truly need maximum strength, or whether stability and finish matter more for a thin or complex part.
• Cost and lead time. Over-specifying strength wastes money and die life. The right alloy is the one that meets the load with the best extrudability and finish — not the strongest one on the chart.

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Alloy-by-Application: Matching Grade to Your Product

Different products lean on different parts of the 6xxx family. The table below maps common end-markets to likely alloy/temper choices and the reasoning behind them. Treat these as informed starting points, not final specifications — the right call still depends on your loads, geometry, and finish.

Application	Likely alloys / tempers	Why
Conveyors & material handling	6061-T6, 6005A-T5/T6	Structural framing and rails need strength and stiffness
Food-service equipment	6063, 6061 (anodized)	Wash-down corrosion resistance and a clean, sanitary finish
Building products	6063-T5/T6; 6005A where load-bearing	Architectural finish and anodizing; 6005A for structural spans
Transportation (RV / trailer / specialty)	6005A, 6061, 6105	Rails, floors, and frames need strength with good extrudability
Electronics enclosures & heat sinks	6063; 6061 where structural	Thin, tall fins and good thermal conductivity; 6061 for rigid housings
Data-center build-out	6063 + 6101 + 6061/6005	Thermal/enclosures, bus bar/power distribution, and racks/structure

That last row is worth pausing on. A single data-center project routinely spans three jobs at once — thermal management (6063 enclosures and heat sinks), electrical distribution (6101 bus bar), and structural support (6061/6005 racks and framing). It's a good reminder that "what alloy should I use?" is often really "which alloys, for which parts?" — and that a single extrusion partner who can run all three keeps the program simpler.

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Common Alloy-Selection Mistakes

• "Use the strongest alloy to be safe." Over-specifying strength costs money, slows extrusion, shortens die life, and often worsens finish. Spec to the load, not to the spec sheet's top line.
• "6061 and 6063 are interchangeable." They diverge where it counts: 6061 for strength and machining, 6063 for finish and corrosion resistance. Swapping one for the other changes how the part performs and looks.
• "All 6xxx alloys anodize the same." Copper and iron content drive anodizing uniformity. 6063's low-copper chemistry is why it finishes more cleanly than 6061.
• Picking the alloy after the profile is finalized. Alloy, temper, and geometry have to be chosen together. Tight tolerances and uneven wall thickness slow extrusion and can force surface-marring secondary work — problems that are far cheaper to design out early.
• "T6 is always better than T5." For thin or complex sections, T5 often gives better dimensional stability and lower cost while still meeting the load.
• Ignoring weld HAZ strength loss. Welding softens the metal beside the joint. Design the joint and the surrounding section for that reduced strength rather than the base-metal number.

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You've Picked the Alloy — That's Half the Job

Choosing the alloy is only the start. The profile, die, and temper all have to work together, and the geometry you draw affects which alloy and temper will actually run well. That's where a custom extruder earns its keep: the right guidance up front prevents the expensive surprises that show up at the press.

If you'd like a second set of eyes, send AES a drawing or just describe the application, and we'll recommend an alloy, temper, and profile approach that fits your part and your budget. AES has extruded custom aluminum in Cincinnati for 50+ years, runs extrusion, machining, fabrication, finishing, and assembly under a single PO, and runs 300 lb minimums — lower than many extruders accept, which makes prototypes and short runs practical. US-made, in the central Midwest. A US extruder you can call: 513.563.2205.

The right alloy only matters if you have a reliable supplier to make it. See why more OEMs are reshoring their extrusion supply: US-made aluminum & the Reshoring Playbook →.