Is Aluminum Softer Than Brass? Hardness & Strength Compared

Is Aluminum Softer Than Brass?

Yes, aluminum is softer than brass in most commonly used alloy grades. A typical free-machining brass like C360 measures around 100-120 HB on the Brinell hardness scale, while general-purpose aluminum alloys like 6061-T6 sit around 95 HB and pure aluminum (1100 series) drops to just 23-32 HB. The exception is high-strength aerospace aluminum such as 7075-T6, which can reach 150 HB and actually exceed many brass grades.

So the short answer is: for the alloys most engineers and sourcing managers deal with daily, brass is the harder metal and aluminum is the softer one. But the full picture depends on which specific alloy you're comparing, how it's been heat-treated, and what your part actually needs to do.

How Is Metal Hardness Measured?

Before comparing brass vs aluminum hardness numbers, it helps to understand what those numbers actually mean. Hardness is a metal's resistance to being dented, scratched, or permanently deformed. Engineers use three main scales to measure it, and each one works a little differently.

Brinell Hardness (HB)

The Brinell test presses a hardened steel or tungsten carbide ball into the metal surface under a known load. The size of the dent left behind determines the hardness number. Bigger dent means softer metal, smaller dent means harder metal. Brinell is the most commonly referenced scale for brass and aluminum alloys in manufacturing, governed by ASTM E10.

Vickers Hardness (HV)

The Vickers test uses a tiny diamond pyramid pressed into the surface. It works on the same principle as Brinell but can measure much smaller areas and thinner materials. Vickers numbers and Brinell numbers are often close to each other for softer metals, which is why you'll see both used in brass and aluminum datasheets.

Mohs Hardness Scale

Mohs is a simpler scratch-resistance scale from 1 (talc) to 10 (diamond). It's less precise than Brinell or Vickers, but it gives a quick sense of where metals sit relative to everyday materials. Brass scores about 3-4 on the Mohs scale. Aluminum sits at roughly 2.5-3. For reference, a copper penny is about 3 and a steel nail is about 6.5.

Brass vs Aluminum Hardness by Alloy Grade

Saying "brass is harder than aluminum" is true as a general rule, but alloy grade changes everything. A heat-treated 7075 aluminum part can actually be harder than some brass alloys. Here's a grade-by-grade breakdown using data from MatWeb and standard engineering references.

Is Brass Stronger Than Aluminum?

Hardness and strength are related but they're not the same thing. Hardness is about resisting dents and scratches. Strength is about resisting pulling forces (tensile strength) and bending before permanently deforming (yield strength). So how strong is brass compared to aluminum?

In most common grades, brass is stronger than aluminum in absolute terms. But aluminum has a much better strength-to-weight ratio because it's about one-third the weight of brass. That's why aerospace and automotive engineers often pick aluminum even when brass is technically "stronger" on paper.

Here's a detail that often gets overlooked: 7075-T6 aluminum is actually stronger than C360 brass in both tensile and yield strength. So saying "is aluminum stronger than brass" depends completely on which aluminum you're talking about. For general-purpose 6061, brass wins. For aerospace-grade 7075, aluminum wins by a wide margin.

Is Brass a Soft Metal?

Brass sits in the middle of the hardness spectrum. It's softer than steel, but harder than pure copper, pure aluminum, gold, silver, lead, and tin. Calling brass "soft" only makes sense when you're comparing it to hardened steels or tool steels. Compared to most non-ferrous metals, brass is actually one of the harder options.

That's what makes brass so popular for precision parts like valve seats, gears, bushings, electrical connectors, and decorative hardware. It's hard enough to resist wear in sliding contact, but soft enough to machine cleanly without excessive tool wear. Think of it as the Goldilocks zone: not too soft, not too hard, just right for a huge range of engineering applications.

In our experience machining both metals across 30+ years of turnkey manufacturing, brass produces some of the cleanest cuts and tightest tolerances of any non-ferrous metal. The chips break short and clean, the surface finish comes out smooth, and dimensional stability stays consistent across long production runs.

How Hardness Affects CNC Machining

If you're an engineer or sourcing manager evaluating brass and aluminum for a CNC project, the hardness difference has real consequences on the shop floor. It affects which tools you use, how fast you can cut, and what kind of surface finish you'll get.

Tool Selection and Wear

Brass is harder than aluminum, so you might assume it eats through cutting tools faster. But brass actually machines very predictably. The chips break short and don't stick to the tool. Carbide inserts (YG-grade) are the standard choice for brass and they last a long time because brass cuts clean.

Aluminum is softer, but it's stickier. The chips are long and stringy, and aluminum has a tendency to weld itself onto the cutting edge of the tool. This is called a "built-up edge" and it ruins surface finish fast. That's why aluminum CNC milling and CNC turning often use polished, coated carbide tools or sometimes even polycrystalline diamond (PCD) tooling to prevent material from gumming up.

Cutting Speed and Surface Finish

Aluminum's softness allows much higher cutting speeds than brass. You can often run aluminum at 500-800+ surface feet per minute (SFM) versus 250-350 SFM for brass. That speed advantage means shorter cycle times and lower per-part costs when machining aluminum, which is one reason aluminum dominates high-volume production.

On the other hand, brass delivers a naturally smoother surface finish straight off the machine. If your part needs a fine finish for sealing surfaces or cosmetic appearance, brass often requires less post-machining polishing than aluminum does.

Brass vs Aluminum: Full Properties Comparison

Hardness is just one property. When you're choosing between brass and aluminum for a real project, you need the full picture. This table compares the most important engineering and commercial properties side by side.

Aluminum has more surface finishing options available, including Type II and Type III anodizing per MIL-A-8625, which can significantly increase its surface hardness and wear resistance. This is one way engineers close the hardness gap between aluminum and brass in finished parts.

When to Choose Brass Over Aluminum (and Vice Versa)

The right metal depends on what the part actually needs to do, not just which one is harder. We recommend using what we call the "Brass-or-Aluminum Decision Matrix" below. Match your project requirements to the recommended material.

Can Brass and Aluminum Be Used Together?

This is a common concern that most brass vs aluminium guides skip over. When brass and aluminum are in direct contact in the presence of moisture, they can suffer from galvanic corrosion. Brass acts as the cathode (the "winner") and aluminum acts as the anode (the "loser"), which means the aluminum corrodes faster than it normally would.

In practical terms, this means a brass fitting screwed directly into an aluminum housing can seize up over time as the aluminum corrodes around the joint. The Fastenal galvanic corrosion guide documents this phenomenon clearly.

If your design requires both metals in the same assembly, isolate them with a non-conductive gasket, coating, or sealant. Alternatively, use fasteners made from a metal that sits between brass and aluminum on the galvanic series (like stainless steel) to reduce the voltage difference. This is an important consideration for any multi-material product and one of the reasons a turnkey manufacturing partner that handles design, material selection, and assembly under one roof can catch problems before they reach production.

How Meco Machines Both Brass and Aluminum

Meco is an IATF 16949:2016 certified turnkey manufacturer with 30+ years of experience machining both brass and aluminum across CNC turning, CNC milling, casting, forging, and assembly processes. Our facilities in Thailand (20,000 m²) and China (16,000 m²) produce millions of precision parts per year in materials ranging from brass C360 and C464 to aluminum 6061, 7075, and ADC12.

Whether your project calls for a brass valve body with tight sealing tolerances or a lightweight aluminum electronics housing that needs anodizing, Meco's engineering team provides DFM feedback with every quote to help you select the right material before tooling begins. Quotes are returned in under 24 hours, and we scale from 10-piece prototypes to 10 million+ production runs with no minimum order quantity.

If you're evaluating brass or aluminum for an upcoming project, contact Meco's engineering team for material guidance and a detailed quote. We also maintain a detailed breakdown of CNC machine costs if you're benchmarking production economics.