Selection summary
Overview
6063 is a heat-treatable 6xxx alloy strongly associated with architectural and general-purpose extrusions. T5 and T6 strength, wall thickness, profile geometry, dimensional tolerance, surface quality, and anodizing requirements must be ordered together.
This page separates standard-oriented limits from typical reference data. Purchase acceptance comes from the ordered specification and certified material test report.
Names and systems
Identity & standards
Similar designations across ASTM, EN, JIS, and other systems are not automatically interchangeable. Product form and ordered standard control chemistry, properties, dimensions, condition, and testing.
Reference chemistry
Composition
| Element | Reference range | Why it matters |
|---|---|---|
| Magnesium | 0.45–0.90% | Precipitation strengthening |
| Silicon | 0.20–0.60% | Extrudability and precipitation strengthening |
| Iron | ≤0.35% | Surface and structure control |
Concise grade-family reference only. Confirm every element limit against the current standard for the exact product ordered.
Condition matters
Reference properties
T5 and T6 extrusion values differ by temper, profile, and thickness
Use ASTM B221 or the ordered product standard and certificate
Typical room-temperature reference value
Environment first
Corrosion behavior
Good atmospheric performance for architectural use with suitable detailing and finish.
Coastal exposure, crevices, fastener couples, and coating damage require system-level review.
Temperature, concentration, deposits, crevices, stress, surface finish, cleaning, and fabrication quality can change service performance.
Service limits
Temperature & service
Strength depends on artificial aging and can change with subsequent thermal exposure.
Delivery condition
Heat treatment & condition
6063 is solution-heat-treatable and precipitation hardenable. T5 commonly uses cooling from the extrusion process followed by artificial aging, while T6 includes solution treatment and artificial aging under the applicable route.
Subsequent welding, bending heat, or coating cure can change local temper and properties; visible profiles also require surface-protection controls through fabrication.
Process route
Fabrication
Excellent extrusion response and generally good anodized appearance.
Bending, machining, welding, and post-fabrication finishing depend on temper and profile design.
Magnetic response: Non-ferromagnetic.
Decision boundaries
Comparisons & substitution
6063 generally offers better extrudability and architectural finish than 6061, while 6061 commonly provides higher structural strength.
5052 suits formed sheet rather than complex extrusions, and 5083 suits marine welded plate; product geometry and temper should lead the comparison.
Where it is used
Applications
Ordering scope
Product forms & standards
Extruded profiles, bar, rod, and tube under ASTM B221/B221M or the ordered extrusion specification, normally with an explicit T5 or T6 temper.
Architectural systems require controlled visible-surface class, die lines, twist, straightness, wall thickness, anodizing/coating, color range, and packing separation.
Sheet, plate, drawn tube, and forgings require separate product standards; an extrusion certificate does not qualify them.
Decision support
Selection guidance
Choose this grade when
- Extrudability, surface appearance, and anodizing quality outweigh maximum strength.
- T5/T6 temper and profile tolerances are explicitly controlled.
Review another grade when
- Higher structural strength or plate availability favors 6061.
- Marine welded plate, demanding fatigue, or aerospace strength governs.
Before ordering
Procurement checklist
State alloy, temper, product specification, dimensions, tolerances, surface finish, edge, and quantity.
Require heat or lot traceability and a certificate showing chemistry, temper, mechanical tests, and ordered inspection.
Confirm fabrication, welding, anodizing or coating, flatness, residual-stress condition, packaging, destination, and delivery target.
State extrusion drawing revision, T5/T6 temper, dimensional tolerances, visible-surface class, anodizing or coating, color range, and packing separation.
Traceable evidence