Ferrous and Non-Ferrous Metals: A Guide for Engineers
A simple way to understand how iron content shapes material choice, cost, and performance.
When choosing a manufacturing metal, one of the first distinctions you'll encounter is whether it's ferrous or non-ferrous.
The word ferrous comes from the Latin ferrum, meaning iron (chemically known as Fe). Ferrous metals contain iron as a major element while non-ferrous metals contain little or no iron.
In this guide, we look at how iron content affects real engineering decisions. We’ll explore where ferrous and non-ferrous materials show their mettle, how they perform across different applications, and what trade-offs matter when you’re designing parts.
What Are Ferrous Metals?
Ferrous metals contain iron as their primary element, which is why they’re usually strong, tough, and magnetic. If you need durability at a reasonable cost, ferrous metals are often where engineers start.
Carbon steels: These everyday workhorses are strong, affordable, and easy to CNC machine or weld. Commonly used for brackets, frames, and general-purpose parts.
Alloy steels: Stronger and more wear-resistant thanks to added elements like chromium or molybdenum. Suitable for high-stress parts such as gears, shafts, and tooling.
Stainless steels: These still contain iron, but chromium gives them a self-healing surface layer that resists corrosion. They’re a reliable choice when you need durability, cleanability, and strong performance, so you’ll see them used in food equipment and medical devices, where hygiene and corrosion resistance matter.
Cast irons: With high carbon content (typically 2–4%), cast irons excel at producing complex shapes. Grey iron absorbs vibration well, while ductile iron offers better impact resistance, which works well for housings, machine bases, and heavy‑duty components.
What Are Non-Ferrous Metals?
Non-ferrous metals contain little or no iron. They’re often lighter, naturally corrosion-resistant, and usually non-magnetic. These qualities are useful in parts where weight, conductivity, or corrosion resistance matter.
- Aluminium: Low density, natural corrosion resistance, and good machinability. Grades like 6061 and 7075 are common in aerospace, consumer electronics, and lightweight structures.
- Copper alloys: Excellent electrical and thermal conductivity. Brass and bronze appear in electrical components, plumbing, and antimicrobial applications.
- Titanium: High strength-to-weight ratio and corrosion resistance. Widely used in aerospace, defence, and medical implants. Non-magnetic and biocompatible.
- Magnesium: Lightest structural metal. Machines quickly but produces highly flammable fine chips, so it requires careful handling.
- Nickel superalloys: Alloys like Inconel offer outstanding strength at high temperatures. Expensive and used only when extreme heat is part of the design environment.
Ferrous And Non-Ferrous Material Comparison
Ferrous and non-ferrous metals behave differently because of their iron content. Not every property divides neatly along ferrous and non-ferrous lines, but several key behaviours do show clear patterns Here are a few key areas where performance diverges and why it matters:
- Corrosion behaviour: While there are a few exceptions, non‑ferrous metals are generally more corrosion‑resistant than ferrous metals because iron oxidises readily. Stainless steel behaves differently thanks to its protective chromium oxide layer, but most other ferrous metals will rust without coatings or treatments. Note that when ferrous and non-ferrous metals touch, galvanic corrosion can occur without proper insulation.
- Weight: Because ferrous metals like steel contain iron, they’re often much denser than lightweight non‑ferrous metals such as aluminium. This is why aluminium is so valuable in weight‑sensitive designs such as aerospace and automotive, where every gram counts.
- Magnetism: Ferrous metals are generally magnetic because they contain iron, while most non‑ferrous metals (like aluminium, copper, and titanium) are non‑magnetic. This matters for motors, sensors, shielding, and any design that depends on magnetic response.
- Conductivity: Non‑ferrous metals typically offer much higher electrical and thermal conductivity than ferrous metals. Copper and aluminium are standout examples, offering excellent heat transfer and electrical performance, while ferrous metals are usually chosen for strength rather than conductivity.
The table below compares key properties across common ferrous and non-ferrous metals.
| Property | Carbon Steel | Stainless 316 | Aluminium 6061 | Titanium Grade 5 | Copper | Brass |
|---|---|---|---|---|---|---|
| Metal Type | Ferrous | Ferrous | Non-ferrous | Non-ferrous | Non-ferrous | Non-ferrous |
| Tensile Strength | 400-550 MPa | 515-620 MPa | 260-310 MPa | 893-920 MPa | 220-310 MPa | 340-470 MPa |
| Density | 7.85 g/cm³ | 8.0 g/cm³ | 2.7 g/cm³ | 4.43 g/cm³ | 8.96 g/cm³ | 8.4-8.7 g/cm³ |
| Corrosion Resistance | Poor (rusts) | Excellent | Excellent | Excellent | Good | Good |
| Magnetic | Yes | No* | No | No | No | No |
| Thermal Conductivity | 50 W/m·K | 16 W/m·K | 152-169 W/m·K | 7 W/m·K | 401 W/m·K | 120 W/m·K |
| Electrical Conductivity | 6-8 MS/m | 1.4 MS/m | 24 MS/m | 0.6 MS/m | 59 MS/m | 15-28 MS/m |
| Machinability Rating | 70% | 45% | 90% | 25% | 70% | 90% |
| Weldability | Excellent | Good | Good | Difficult | Good | Fair |
| Typical upper service temp | 425°C | 870°C | 150 °C | 400°C | 400°C | 200°C |
| Relative Cost | € | €€ | €€ | €€€€€ | €€€ | €€ |
* Non-magnetic when annealed but can become slightly magnetic after heavy cold work or welding.
Values in this table are approximate and will vary based on alloy selection, heat treatment, part geometry, and service environment.
For a deeper dive into hardness and strength behaviour, check out our material hardness testing guide.
Industry Applications
When you look at real applications, you start to see patterns in where ferrous and non-ferrous metals tend to appear. Engineers don’t usually choose materials just because they’re ferrous or non-ferrous—specific properties like strength, weight, conductivity, and corrosion resistance usually drive the decision. But these broad families still help explain why certain metals show up again and again in particular industries.
- Automotive: Ferrous steels are used for crash structures because of their strength and cost. Non-ferrous aluminium helps reduce weight in wheels, body panels, and structural parts.
- Aerospace: Weight matters most, so non-ferrous aluminium, titanium, and nickel alloys dominate.
- Medical: Stainless steel (ferrous) is common in tools and equipment. Titanium (non-ferrous) is the standard for implants.
- Marine: Copper alloys resist saltwater better than unprotected ferrous metals.
- Consumer electronics: Copper (non-ferrous) supports conductivity, while steel brackets (ferrous) offer structure.
- Robotics: Aluminium (non-ferrous) provides lightweight frames. Stainless steel (ferrous) adds durability for high-wear parts.
You can see more examples in our industries overview on the Protolabs site.
Selecting Ferrous or Non-Ferrous Metals
Choosing between them usually depends on what your design needs most. Here are a few quick guidelines engineers use:
- Need high strength at an affordable cost? → Ferrous metals are often the most economical way to get strong, durable parts.
- Need high strength at low weight? → Non-ferrous metals like titanium and high‑strength aluminium alloys shine here.
- Need corrosion resistance without coatings? → Non-ferrous metals (and stainless steels) are strong candidates.
- Need magnetic response? → Ferrous metals are the way to go.
- Need good electrical or thermal conductivity? → Copper and aluminium (non‑ferrous) are your best options.
- Need biocompatibility? → Titanium (non‑ferrous) is the top choice.
FAQ
What makes a metal ferrous or non-ferrous?
expand_less expand_moreFerrous metals contain iron as a major element, whereas non-ferrous metals contain little or no iron.
Which type is stronger?
expand_less expand_moreFerrous metals (such as most steels) often have the highest tensile strength, while non-ferrous metals (such as titanium) offer the best strength-to-weight ratio.
Why are non-ferrous metals more expensive?
expand_less expand_moreThey’re harder to extract and refine, and sometimes less abundant.
Can ferrous and non-ferrous metals be used together?
expand_less expand_moreYes, but protect the joint from galvanic corrosion.
How does material choice affect cost and lead time?
expand_less expand_moreMachinability, tool wear, and process compatibility all play a role.
Is stainless steel ferrous or non-ferrous?
expand_less expand_moreIt’s ferrous. It contains iron but behaves differently from carbon steel because chromium creates a protective oxide layer.
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