Different Types of Alloy Steel: Why They are Important

stainless steelA Little History
Steel has been used for thousands of years because of its incredible strength and durability. Originally, it was simply used as iron, until someone discovered how to make it in to steel. The very first known production of steel was almost 4,000 years ago when ironware was used to create steel weapons which were used by the Roman military.

Current Day
Nowadays, iron is smelted and contains carbon, but to actually become steel, it has to be have the carbon reduced somewhat. Other elements can then be added to make the different kinds of alloy steel that are below. One of the best things about steel is that it is mostly all recycled by now. The majority (69%) of the steel just in the U.S. is recycled. What’s even more amazing, though, is that steel never loses its strength or integrity throughout the entire recycling process.

Steel is a large part of the metal family. All types of steel are alloys. Alloy steels are produced by adding metals like nickel, tungsten, and chromium to iron. Every time you add a different element to iron, a different amount, or a different combination, you create a different kind of alloy steel. Below are several types of alloy steels that can be produced.

Alloy Steel
This is the general term given to iron when another element has been added. Alloy steels are the backbone of the construction industry because of their inexpensive cost, easy accessibility, and response to heat treatments.

Stainless steel
Stainless steel can also be called inox steel. It contains at least 10.5% chromium and does not corrode, rust or stain very easily. However, in low oxygen or poorly ventilated areas, the stain resistance factor lowers. The reason why stainless steel is resistant to corrosion and rust is because the chromium forms a film of chromium oxide, which blocks oxygen diffusion from the surface and prevents corrosion from getting into the internal structure. Different level grades and finishes are available for stainless steel.

Carbon steel
Carbon steel can also be separated into three categories: low, medium, and high. Low carbon steel contains 0.04% to 0.30% carbon. Medium carbon steel typically has about 0.31% to 0.60%, and high carbon steel can range between 0.61% and 1.50%.

Low carbon steel is probably the largest group, and it covers a large variety of shapes. Medium carbon steel is stronger than low carbon steel, so it is harder to mold and cut. High carbon steel is the strongest and is extremely difficult to cut and bend. After being heat treated, high carbon steel is incredibly hard and brittle.

Tool Steel
This is basically the term that is used for a wide range of abrasion resistant, extremely hard steels. Tools like this are usually used for cutting, molding, stamping or extrusion. It is usually sold in rectangular or round shapes.

Galvanized Steel
You cannot really talk about steel without bringing up galvanizing. This is when zinc is applied to the steel in order to prevent rusting. The zinc forms a corrosion resistant coating on every part of the metal. It serves as a protection against dents, scratches, or damage. The zinc will take the majority of the abuse, leaving the steel unharmed. Galvanized steel strapping is used to secure shipments, even by the military, because of its strength and resistance to the elements.

There are over 3,500 different grades of steel so it would be impossible to cover every one but you may be interested to know that three-quarters of the steels have been produced within the most recent 20 years. Steel is now more dent resistant and almost 30% times stronger than it was even just 10 years ago. About 83,000 tons of steel was used to make the Golden Gate Bridge, but because of how much stronger steel now is, only half of that would be needed to make the same bridge now. The leaps and bounds that the steel industry has made are more than any other metal so far.