Mill Finish 3005 3105 Aluminum Sheet

06/11 2025

When it comes to durable, corrosion-resistant, and aesthetically pleasing aluminum sheets, Mill Finish 3005 and 3105 aluminum sheets shine as two of the industry’s most versatile and widely applied materials. Their unique combination of alloy composition and surface finish makes them ideal for a number of functional uses – from architectural applications to consumer goods.

Mill Finish in Aluminum Sheets

Mill finish refers to the natural, untreated surface condition of aluminum sheet as it leaves the rolling mill. This finish is characterized by a dull, matte appearance with subtle rolling lines. While mill finish sheets can be subjected to additional surface treatments (e.g., anodizing or painting) to boost aesthetics and corrosion resistance, many functional applications favor the natural finish for its cost-effectiveness and ready-to-use properties.

Working with Mill Finish 3005 and 3105 aluminum sheets daily, I've noticed a significant difference in their workability. While both are popular for their formability and corrosion resistance, the 3005, with its slightly higher manganese content, tends to spring back less after bending, making it preferable for applications needing precise shapes. The 3105, however, boasts superior strength, especially important in applications where the sheet will experience stress or impact. The mill finish itself presents its own challenges; its inherent softness makes it susceptible to scratching and marring during handling and processing, requiring careful attention to storage and transport. We often see issues arising from improper stacking, leading to surface imperfections that necessitate extra cleaning before further processing.

Beyond the technical specifications, I've found that the subtle variations in the mill finish between batches is crucial for consistent production. Even with the same alloy designation, differences in the rolling process can affect surface texture and reflectivity. This means that close collaboration with the mill is essential, ensuring a consistent supply that meets our manufacturing needs. We've invested in advanced surface inspection systems to help us detect even slight variations and adjust our processes accordingly to minimize waste and maximize yield. The "mill finish" might sound simple, but maintaining consistent quality in this seemingly basic aspect is a continuous learning process.

The inherent smoothness and cleanliness of mill finish aluminum provide an excellent base for subsequent processing or direct use where visual appearance combined with performance is prioritized.

Both the 3005 and 3105 alloys belong to the 3xxx series of aluminum, where manganese is the principal alloying element. This gives the metal excellent corrosion resistance, modest strength improvements over pure aluminum, and enhanced workability.

Properties	3005 Aluminum Sheet	3105 Aluminum Sheet
Alloy Series	3xxx (Aluminum-Manganese Series)	3xxx (Aluminum-Manganese Series)
Typical Applications	Roofing, siding, outdoor furniture	Roofing, siding, HVAC panels, rain carrying systems
Strength Level	Medium strength	Slightly lower strength than 3005
Surface Finish	Mill finish (natural)	Mill finish (natural)

Functions and Applications

1. Architectural Panels and Cladding

3005 and 3105 mill finish sheets are excellent for external construction surfaces including siding and roofing panels. Their alloy composition provides durability and corrosion resistance without the need for extensive post-treatment, especially suitable for coastal and industrial locations where corrosive environments prevail.

2. HVAC Components

The sheets are frequently used to fabricate ductwork, air handling systems, and heat exchangers thanks to their high formability and resistance to atmospheric corrosion.

3. Transportation Industry

Being lightweight yet resilient, mill finish 3005 and 3105 sheets contribute directly to fuel efficiency when used in truck trailer skins and other vehicle panels.

4. Appliances and Furniture

These aluminum sheets are also chosen for domestic and industrial appliances, outdoor furniture, and equipment panels for their resistance to moisture, ease of fabrication, and clean well-machined look.

Technical Details: Chemical Composition and Temper

Both 3005 and 3105 aluminum sheets follow precise standards that promote reproducible manufacturing quality and performance.

Chemical Composition:

Element	3005 (%)	3105 (%)
Aluminum (Al)	Balance	Balance
Manganese (Mn)	1.0 – 1.5	0.5 – 1.0
Iron (Fe)	≤ 0.7	≤ 0.7
Silicon (Si)	≤ 0.6	≤ 0.6
Copper (Cu)	≤ 0.3	≤ 0.3
Magnesium (Mg)	≤ 0.2	≤ 0.2
Zinc (Zn)	≤ 0.1	≤ 0.1
Titanium (Ti)	≤ 0.2	≤ 0.2

Compliance with Standards

Mill finish 3005 and 3105 aluminum sheets conform to rigorous national and international standards that guarantee their mechanical and chemical attributes:

ASTM B209: Covers aluminum and aluminum-alloy sheet and plate.
ASTM B209M: Metric equivalent of ASTM B209.
AA (Aluminum Association) 3XXX Series Standards.
EN 573-3 (European standard): Specifies chemical composition.

These standards ensure reliability in a wide range of applications and compliance with fabrication equipment specifications.

Alloy Temper Designations

The temper states denote the hardness and strength of aluminum sheet, influenced chiefly by cold working and annealing. For mill finish sheets:

Common tempers include H14, H24, H22, H16 (strain-hardened but partially annealed for varying strength/flexibility levels)
For example:
H14: Quarter hard (good strength and formability)
H24: Quarter-hard, partially annealed
O anneal: Fully annealed for max softness

Manufacturers offer varying tempering to suit specific formation, pressing or cutting requirements.

Mechanical Properties*

Property	3005-H14	3105-H14
Tensile Strength	~145 – 205 MPa	~110 – 170 MPa
Yield Strength	~110 – 165 MPa	~90 – 140 MPa
Elongation (%)	~6 – 12%	~6 – 15%
Hardness (Brinell)	~35 – 55 HB	~30 – 50 HB