Steel is a catch-all phrase use to describe a group of iron alloys. These alloys all have one thing in common: malleability. Steels can all be melted down and used in the injection moulding process to create everyday items. Steels can be cast directly into moulds, or can be made into other forms which allow them to be heat-treated and worked on at a later stage. Here are four different types of steel:
- Standard Steels.
- Carbon steel. A carbon steel only requires carbon to create a successful alloy. Other alloys will have minimum requirements for materials such as chromium, nickel, tungsten and a handful of other elements. Carbon steel can range from low-carbon to ultra-high carbon (1.0-2.0%) content. Generally, the greater the carbon content, the more the alloy can be hardened, increasing strength, wear and impact resistance.
- Alloy steel. Steel is alloyed with other elements in order to improve its mechanical properties. The mixture of other elements can be anywhere from 1% to 50%, dividing alloys into two camps: low alloy steels and high alloy steels. The most common alloy steel is low alloy steel. Alloy steels are used to improve harden-ability and corrosion resistance. Often a low-alloy steel will have less carbon in it, as the low non-carbon alloy materials in combination with high carbon content can make it difficult to weld.
- Stainless steel. This is the stuff kitchen benches are made out of. Also known as inox steel or corrosion-resistant steel (usually in the aviation industry), it is an alloy containing a large amount of chromium by mass (a minimum of 10.5%-11%). Stainless steel does not stain, rust or corrode as easily as ordinary steel (it is a myth that it will not corrode at all). The main difference between stainless steel and other types of steel alloy is the amount of chromium present. The chromium in the alloy acts as a film against the rust which usually plagues steel by forming a film of chromium oxide, which acts as a barrier, not allowing corrosion to spread from the surface inwards. Its resistance to corrosion and staining make it an ideal candidate for commercial applications, and there are over 150 different varieties in use, each with specific and differing properties.
- Tool steels. These are a collection of steels and alloys, collectively grouped because their particular properties make them ideal for use in making tools. They are commonly resistant to abrasion or corrosion, are hard, impact resistant and are able to hold a cutting edge. There are a number of different grades of tool steel, each with one or more of its properties enhanced for use in its industry. Tool steels are used in the creation of moulds for injection moulding, as they are able to withstand the production of thousands of parts without showing signs of abrasion.
Steel has thousands of applications, and each application has its own particular makeup of compounds. Steel’s amazing properties mean that its makeup can be specifically targeted for the needs of the designer or engineer.