What is the difference between 6061 and 6063?

6063 is softer (214 MPa yield) and primarily used for extrusions and architectural shapes; 6061-T6 is stronger and is the standard for machined parts and plate.

Can 6061-T6 be welded?

Yes, but welding reduces strength in the heat-affected zone to roughly the -T4 temper level (about 145 MPa yield); post-weld heat treatment can restore T6 properties but adds cost.

For high volumes, is switching to a 6061 casting worth it?

Above roughly 2,000–5,000 pieces depending on complexity, a die-cast or permanent-mold casting with secondary CNC machining on critical features can reduce unit cost by 30–50%.

Aluminum does not rust in the iron-oxide sense; 6061 forms a protective oxide layer and has good general corrosion resistance, though it will pit in saltwater environments without coating.

Aluminum 6061-T6 for CNC Machining: Why It is the Default and When to Upgrade

Why 6061-T6 Is the CNC Default

Aluminum 6061-T6 is the most widely used alloy for custom CNC machined parts because it offers good strength (276 MPa yield), excellent machinability, corrosion resistance in most environments, predictable anodizing results, and a price roughly 30–40% below 7075-T6. Around 80% of aluminum CNC parts are appropriately made from 6061-T6.

What the T6 Temper Means

T6 means the material has been solution heat-treated (heated to about 530°C to dissolve alloying elements, then quenched) and artificially aged (held at about 160°C for 8–18 hours) to precipitate strengthening phases. This raises yield strength from roughly 55 MPa in the annealed -O condition to 276 MPa in -T6.

Key Properties at a Glance

Property	6061-T6 Value	Note
Yield strength	276 MPa	Comparable to mild steel for stiffness-to-weight
Hardness (Brinell)	95 HB	Machines cleanly with carbide tooling
Elongation	12%	Good formability before heat treatment
Machinability rating	Good	Minimal built-up edge, excellent chip evacuation
Corrosion resistance	Good	Suitable for most outdoor and industrial environments
Anodizing response	Excellent	Clear, black, and color anodizing all work well

Parts That Belong in 6061-T6

Enclosures, housings, and covers where dimensional stability matters more than ultimate strength
Mounting brackets, adapter plates, and fixture bases in the 3–12 mm thickness range
Prototype parts that may later move to 7075 or a different alloy for production
Parts requiring cosmetic or hard-coat anodizing, where 6061 anodizes more evenly than 7075

When to Upgrade and What to Specify

Upgrade to 7075-T6 for high-stress or fatigue-loaded components; 2024-T3 for aerospace fatigue; 5052-H32 for welded sheet metal assemblies
Specify 6061-T6 on the PO, not just 6061; the temper designation determines actual strength
Request material certificates (mill test reports) on structural or safety-critical parts
Watch for internal stress in plates over 50 mm; ask about stress-relieved material if flatness is critical

TruPart Precision, an ISO 9001 CNC shop in Dongguan, stocks 6061-T6 in plate, bar, and block form for fast turn-around. It is the default choice for good reason, and the best alloy to start with unless your application forces a different selection.

Frequently Asked Questions

What is the difference between 6061 and 6063?
6063 is softer (214 MPa yield) and primarily used for extrusions and architectural shapes; 6061-T6 is stronger and is the standard for machined parts and plate.
Can 6061-T6 be welded?
Yes, but welding reduces strength in the heat-affected zone to roughly the -T4 temper level (about 145 MPa yield); post-weld heat treatment can restore T6 properties but adds cost.
For high volumes, is switching to a 6061 casting worth it?
Above roughly 2,000–5,000 pieces depending on complexity, a die-cast or permanent-mold casting with secondary CNC machining on critical features can reduce unit cost by 30–50%.
Does 6061-T6 rust?
Aluminum does not rust in the iron-oxide sense; 6061 forms a protective oxide layer and has good general corrosion resistance, though it will pit in saltwater environments without coating.