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Ferrous and Non-Ferrous Metals

Ferrous and Non-Ferrous Metals

What is the difference between ferrous and non-ferrous metals? In case of ferrous (ferrum=iron) metals, the base metal is iron. They compose a large part of the overall metals in use today. This is made possible by their properties that suit many different industries and use-cases.

Non-ferrous metals, on the other hand, do not include iron. This distinction is made because it brings along a certain characteristic change that non-ferrous metals do not provide.

Properties of ferrous metals

Ferrous metals may include a lot of different alloying elements. Some examples are chromium, nickel, molybdenum, vanadium, manganese. Those give ferrous steels mechanical properties that make them widely used in engineering. 

A list of ferrous metal properties:

  • Durable
  • Great tensile strength
  • Usually magnetic
  • Low resistance to corrosion
  • A silver-like colour
  • Recyclable
  • Good conductors of electricity

These qualities make them usable in constructions of long-lasting skyscrapers. On top of that, they are utilised in making tools, vehicle engines, pipelines, containers, automobiles, cutlery etc.

Ferrous metal examples

We made a list of ferrous metals along with a description of each. They all have different specifications, resulting in a variety of applications.

Non-alloy steels

Non-alloy steels are also known as carbon steels because carbon is the alloying element there. Yes, a little confusing as the name suggests one thing but that’s how it often is in the world of metals. Although there are other elements also present, their content is low enough to not make an impact on the material properties. Those elements are sulphur, phosphorus, silicon and manganese. Sulphur and phosphorus can actually have a detrimental effect on the steel’s quality but again, not with such low-level content.

Although the term “non-alloy steels” doesn’t get much mention in a typical engineering company as such, our beloved structural steels like S235, S355 etc belong to this group.

Non-alloy steels are classified by their carbon content as low, medium and high carbon steel. Each has their own uses and the characteristics vary. Also, different treatment methods are available accordingly.

Low carbon steel

Low carbon, or mild steels contain 0.05…0.25% of carbon. They are pretty low-cost and very well suited for bending operations. The surface hardness can be increased through carburising.

The low cost and malleability low carbon steels are widely used. Some examples include bolts and nuts, forgings, medium-loaded details etc.

Examples of low carbon steels: C10E/1.1121, C15E/1.1141

Medium carbon steel

Medium carbon steels contain 0.25…0.6% of carbon. The higher carbon content increases their strength and hardness compared to low carbon steels. At the same time, the ductility decreases. The increase of carbon and manganese allows tempering and quenching.

Gears made from ferrous metals
Gears, shafts and axles – all ferrous metal

Medium carbon steels are mainly used for making different automotive industry components like gears, axles, shafts but also bolts, nuts, screws etc. Steels ranging from 0.4…0.6% are also suitable for everything related to locomotives and rails.

Examples of medium carbon steels: C40E/1.1186, C60E/1.1221

High carbon steel

The carbon content numbers for high carbon steels vary according to different sources. Some have more sub-groups, while other stop with high carbon steels that start with 0.6% carbon content and end around 1%. We’ll go with the second interpretation.

These are the strongest of this group, making it suitable for applications where resistance against mechanical wear is needed. Another quality of high carbon steels is their tendency to keep a shape. As a downside, the weldability, ductility and impact toughness are all inferior to steels with less carbon.

Tools made from steel
Steels are also classified by uses. Tool steels and high carbon steels overlap.

The shape-keeping quality makes them useful as springs. Other use-cases include blades, rail steels, wire rope, wear-resistant plates, all kinds of tools etc.

Examples of high carbon steels: C70U/1.1520, C105U/1.1545

Alloy steels

Alloy steels make up another sub-group of ferrous metals. Steel’s alloying elements are chrome, nickel, silicon, copper, titanium etc. Each has their own effect on material properties. Of course, they are usually combined, so the end products has a bit of everything. We discuss how the most common elements affect the outcome.

Chromium

Chromium is the element responsible for creating stainless steel. Presence of chromium at levels above 11% make a metal corrosion-resistant. As discussed in the materials wear article, the protection takes place through creating an oxidised chromium layer on top of the metal. This means that the base metal does not get into contact with oxygen and the danger of corrosion is greatly diminished.

On top of that, chromium also increases tensile strength, hardness, toughness, resistance to wear etc.

Manganese

Manganese improves ductility, wear resistance and hardenability. The latter is done through quenching where manganese has a significant impact. It diminishes the danger of defect formation during the process by making it more stable.

It also eliminates the formation of harmful iron sulfides, increasing strength at high temperatures.

Nickel

Cutlery from alloy steel
Stainless steel cutlery helps us avoid the taste of rust

Its main purpose is to increase ductility and corrosion resistance in combination with other elements, namely chromium. When chromium content is around 18% and nickel at 8%, we get an extremely durable stainless steels.

Silicon

Improves strength and provides elasticity in springs. Another significant effect is increasing a metal’s magnetic properties.

Titanium

Improves strength and corrosion resistance, limits austenite grain size.

Vanadium

The formation of vanadium carbides limits the grain size. This has an effect on increasing a material’s ductility.

It also increases strength, hardness, wear and shock impact resistance. Because of its effectiveness, the amounts must be held low. Otherwise, it can have a negative impact on material properties.

Molybdenum

Molybdenum has a large effect on steel alloys at high temperatures. It improves mechanical properties but also resistance to corrosion and acts as an amplifier for the effects of other alloying elements.

Cast iron

Cast iron is an alloy of iron and carbon, with a carbon content somewhere between 1.5 and 4 percent. There are also other elements present – namely silicon, manganese, sulphur and phosphorus.

Cast iron pan
We all know the 40-year-old heavy cast iron pans in grandma’s kitchen

Although it is brittle, its hardness makes it resistant to wear. The final form of a cast iron product is gained through casting. This process only needs minor after treatment, making it possible to form a needed shape.

The properties of cast iron:

  • Great castability
  • Relatively cheap
  • High compressive strength
  • Good wear resistance
  • Low melting point

What is a non-ferrous metal?

Non-ferrous metals do not contain iron. They are softer and therefore more malleable. They have industrial uses as well as aesthetic purposes – precious metals like gold and silver are both non-ferrous. Actually, all pure metal forms, except for pure iron, are non-ferrous.

Non-ferrous metals’ properties

Non-ferrous metals’ advantages make them usable in many applications instead or iron and steel.

The properties of non-ferrous metals:

  • High corrosion resistance
  • Easy to fabricate – machinability, casting, welding etc
  • Great thermal conductivity
  • Great electrical conductivity
  • Low density (less mass)
  • Colourful
  • Non-magnetic

Non-ferrous metals list

Again, we are going to provide some examples of non-ferrous metals and use-cases for each group.

Copper

Copper roofing
When oxidised, copper turns green

Copper is pretty widely spread in the industrial sphere. Add the alloys brass (copper and zinc) and bronze (copper and tin), and you may already see the many uses of copper. If not, we can help you out. For mechanical engineers, slide bearings and bushings may be the most known uses.

Still, copper and copper alloy properties allow more applications:

  • High thermal conductivity – heat exchangers, heating vessels and appliances etc
  • High electrical conductivity – used as an electrical conductor in wiring and motors
  • Good corrosion resistance – beautiful but expensive roofing
  • High ductility – makes the material very easily formable and suitable for making statues

Aluminium

In engineering terms, a very special and important metal. May not be so useful in everyday application because of the price but its combination of low weight and great machinability make it the go-to metal in yachts, planes and many automotive parts.

Aluminium is also the base metal in many alloys. The best known are probably duralumin, Y-alloy and magnalium.

Aluminium properties include:

  • Corrosion resistant
  • Good conductor of heat and electricity (but less than copper) – in combination with ductility and malleability replaces copper in some instances
  • High ductility and lightweight
  • Becomes hard after cold working, so needs annealing

Lead

For the average person, lead may ring a bell related with bullets (which are now without lead) and gas (which has a sign “unleaded”). Although at first added to fuel to decrease motor knocks, it turned out to be heavily unhealthy when vaporised into the atmosphere.

The same goes for bullets and shooting range employees who got health problems because of it. But why add it in the first place? Because lead is the heaviest common metal. As it doesn’t react easily with other substances, they are still used in batteries and power cables, acid tanks and water pipes.

Lead properties are:

  • Very heavy
  • Resistant to corrosion – doesn’t react with many chemicals
  • Soft and malleable

Zinc

Zinc on its own doesn’t mean much to the average person. As an alloying element, on the other hand, it has a wide range of purposes. It is mainly used for galvanising steel in all kinds of fields. Galvanising makes a material more durable against corrosion.

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