Aluminum Alloy 6061-T6

Overview

6061 is the most versatile and widely used heat-treatable aluminum alloy, with magnesium and silicon as principal alloying elements. The T6 temper (solution heat-treated and artificially aged) provides medium-to-high strength, excellent corrosion resistance, good machinability, and ready weldability. Aluminum 6061 is about one-third the weight of steel with roughly half the strength of mild steel.

Specific Gravity

Specific gravity (relative density) is the ratio of material density to water density (1,000 kg/m³).

Aluminum's specific gravity of about 2.7 means it is 2.7 times heavier than the same volume of water, but only about 34% the weight of steel (specific gravity 7.85).

Unit Weight

Unit weight (weight density) expresses the weight per unit volume:

Quick reference: a 1 m³ block of 6061 aluminum weighs 2,700 kg (2.7 t); the same volume of steel weighs 7,850 kg.

Unit Conversion

Examples: 2,700 kg/m³ = 168.6 lb/ft³ = 0.0975 lb/in³ = 26.5 kN/m³. For quick mental math, remember 2.7 g/cm³ = 2,700 kg/m³ = 0.0975 lb/in³.

Mechanical Properties (6061-T6)

Comparison to Steel

Thermal Properties

Corrosion Resistance

Aluminum forms a thin, self-healing oxide layer (Al₂O₃) that provides excellent atmospheric corrosion resistance. It resists:

• Rural, urban, and mild industrial atmospheres
• Fresh water (pH 4.5-8.5)
• Many chemicals (nitric acid, organic acids)
• Marine environments (better than carbon steel; can pit in stagnant seawater)

Not resistant to:

• Strong acids (HCl, sulfuric above dilute concentrations)
• Strong alkalis (caustic soda dissolves aluminum)
• Mercury and mercury salts (catastrophic embrittlement)
• Prolonged contact with wet concrete/mortar (alkaline attack)

Common Tempers

Applications

• Aircraft and aerospace structures (historically 2024/7075; 6061 for secondary structure)
• Truck and trailer bodies, rail cars
• Marine structures (boats, docks, gangways)
• Architectural — window frames, curtain walls, roofing
• Bicycle frames, ladders, scaffolding
• Heat exchangers (excellent thermal conductivity)
• Pressure vessels and piping for cryogenic service (down to -270°C)
• Machined parts, fixtures, tooling plates

Fabrication Notes

• Weldable with TIG or MIG using 4043 or 5356 filler (weld zone loses T6 strength — returns partially with age)
• Excellent machinability; chip-breaking alloys available
• Can be anodized for superior corrosion resistance and coloring
• Cold working increases strength (temper H116, H32 for sheet)
• T6 temper can be restored by re-heat-treatment after welding

Summary

6061-T6 aluminum (density 2700 kg/m³, yield 276 MPa) offers excellent strength-to-weight, corrosion resistance, and thermal conductivity. About 1/3 the weight of steel with comparable yield strength but 1/3 the stiffness (deflects more under load). Standard for lightweight structures, marine applications, heat exchangers, and architectural use. Watch for galvanic corrosion when dissimilar metals contact aluminum.

Aluminum Alloy Density Table

Aluminum Weight Calculation

Formula

Where:

• W = weight (kg)
• V = volume (m³)
• ρ = density (kg/m³), typically 2,700 for 6061-T6

Example Calculations

Aluminum Plate: A 1000 × 500 × 10 mm aluminum 6061 plate:

• V = 1.0 × 0.5 × 0.01 = 0.005 m³
• W = 0.005 × 2,700 = 13.5 kg
• Compare: same steel plate = 39.25 kg (2.9× heavier)

Aluminum Round Bar: Ø50mm × 1000mm 6061-T6 bar:

• V = π × (0.025)² × 1.0 = 0.00196 m³
• W = 0.00196 × 2,700 = 5.3 kg
• Compare: same steel bar = 15.4 kg

Aluminum Extrusion (6063): Standard 40×40mm square tube, 2mm wall, 3m length:

• V ≈ (0.04² - 0.036²) × 3 = 0.000912 m³
• W = 0.000912 × 2,700 = 2.46 kg

Aluminum vs Other Metals Weight Comparison

Aluminum 6061-T6 vs 7075-T6

Related Engineering Tools

• Aluminum Weight Calculator — Calculate weight from dimensions
• Metal Weight Calculator — Compare metal weights
• Steel Weight Calculator — Steel weight reference
• Copper Weight Calculator — Copper weight reference
• Density Calculator — General density calculations
• Beam Deflection Calculator — check deflection when using aluminum beams
• Material Strength Basics — modulus, yield, and strength concepts
• Steel Material Properties — compare with structural steel

Frequently Asked Questions

What is the density of aluminum 6061-T6? Aluminum 6061-T6 has a density of 2,700 kg/m³ (0.0975 lb/in³). This is approximately one-third the density of steel (7,850 kg/m³).

What is the specific gravity of aluminum? The specific gravity of 6061 aluminum is 2.70 (density 2,700 kg/m³ ÷ 1,000 kg/m³ water). All aluminum alloys fall in the 2.66-2.81 range.

What is the unit weight of aluminum? Aluminum unit weight is 26.5 kN/m³ in SI units, 168.6 lb/ft³ in imperial, or 0.0975 lb/in³ in US customary. A 1 m³ block weighs 2,700 kg.

How do I convert aluminum density from kg/m³ to lb/ft³? Divide kg/m³ by 16.018. Example: 2,700 ÷ 16.018 = 168.6 lb/ft³. For lb/in³, divide kg/m³ by 27,680.

How much does aluminum weigh per square meter? A 1mm thick aluminum 6061 sheet weighs 2.7 kg/m². A 10mm plate weighs 27 kg/m². Compare: 10mm steel plate = 78.5 kg/m².

Is aluminum lighter than steel? Yes, aluminum is about 1/3 the weight of steel. A structure made from 6061-T6 aluminum weighs approximately 35% of an equivalent steel structure, though aluminum requires larger cross-sections due to lower stiffness (1/3 of steel).

What is the strongest aluminum alloy? 7075-T6 is the strongest common aluminum alloy with yield strength of 503 MPa, comparable to many steels. However, it has poor weldability and moderate corrosion resistance. 6061-T6 (276 MPa) is the best all-round alloy.

How do you calculate aluminum weight? Weight = Volume × Density. For a plate: W = Length(m) × Width(m) × Thickness(m) × 2700. Use our Aluminum Weight Calculator for instant results.

6061-T6 Aluminum — Detailed Engineering Data

6061-T6 is the most widely used aluminum alloy in structural engineering. The T6 temper (solution heat-treated at 530C, quenched, then artificially aged at 160C for 18 hours) provides the best combination of strength, corrosion resistance, and weldability.

Chemical Composition

Mechanical Properties by Temper

6061-T6 Design Allowables (ASME BPVC Section II)

6063 Aluminum — Extrusion Alloy

6063 is the most common aluminum alloy for extruded shapes (window frames, architectural profiles, heat sinks) due to its excellent extrudability and surface finish.

6063 is weaker than 6061 but produces smoother extrusion surfaces and takes anodizing better — preferred for architectural applications.

2024-T3 Aluminum — Aerospace Alloy

2024-T3 is a high-strength aerospace alloy (used historically for aircraft skins and structures). Higher strength than 6061 but poor corrosion resistance and weldability.

Aluminum Density Lookup by Alloy