What is the difference between steel and iron?

The incorrect use of words is widespread iron and steel, both in the everyday context but also in the specialist or technical one. In fact, it is often easy to create confusion between what is essentially steel but is wrongly labeled as iron. From a technological point of view, we are talking about two completely different materialsalthough they appear to be linked by some production processes: in fact, Steel is an alloy that is produced from iron, which is a metal. In some ways, we have a big similarity with what often generates confusion between the technological identification of the cement and concreteobviously with the due proportions. In this article we try to clarify in a simple way what the differences are between iron and steel and what Application contexts can easily lead us to correctly distinguish between the two.

The iron

The iron (Fe) it’s a chemical element and represents the main ingredient of all those alloys that make, for example, construction materials, both for civil/building use but also for industrial, mechanical or naval use. It also represents one of the most common metals in the world. Its presence is fundamental in the production process of some alloys. However, its use as a construction material is difficult to apply, as has poor mechanical and technological properties.

It is extracted downstream of a refining process, starting from naturally present materials composed of other elements, such as sulphides or silicates. In general, the refining process takes place at high temperatures and allows the separation of the raw material from the remaining parts: the quality of the process implicitly outlines the quantity of impurity still present in the final metal, which is why It is difficult to obtain pure iron starting from any production process. Its use, rather than for structural purposes, is instead linked to its important magnetic properties and is widely used in fields such as medicine or agriculture (it is used as a nutrient for plants).

The steel

The term steel specifically identifies some particular alloys composed mainly of iron and carbonas well as other elements that are introduced to create specific products of the case. The quantity of carbon present within the alloy must follow predetermined percentages: the percentage of carbon present in the alloy must be around between 1.7% and 2% to obtain an alloy that can be defined steel. Based on the actual value of this percentage, a steel can be subsequently classified by Sweet to very hard, with other intermediate categories that vary as the amount of carbon present increases.

How does the percentage of carbon affect? ​​We can say that the more carbon there is in the alloy, the more the steel that is formed performs in terms of resistance. However, the presence of an excessive quantity of carbon is due to the alloy becoming brittlewhich therefore loses its ductility characteristics. The choice of alloy is therefore conditioned by the specific application of the case. In the case in which the percentages of carbon exceed those indicated above, then we are no longer talking about steel, but rather about cast iron.

The other elements of the alloy

Other elements are inserted into the alloy for the production of steels. The presence of these additional elements strongly depends on the purposes of use of the alloy. However, in some cases the presence of these additional elements is dictated by the same impurities due to the extraction process of the iron at the start.

In general, elements such as manganese (Mn) and silicon (Si) are inserted to obtain weldable steel with high mechanical characteristics. The chromium (Cr)in some cases, is added to increase mechanical resistance but also to reduce sensitivity to corrosion. In this regard, elements such as chromium (Cr), copper (Cu) and phosphorus (P) can be added for create a particular steel alloy, called CorTencapable of protect yourself from spontaneous corrosion of metal in aggressive environments.