Steel is one of the fundamental materials of modern industry, widely used in construction, transportation, infrastructure and mechanical engineering. Its history, however, goes back much further and follows the evolution of ironworking and metallurgy through to modern steelmaking.
What is steel?
Steel is a metal alloy consisting primarily of iron and carbon, with other elements added to modify its properties.
Carbon content plays a fundamental role, influencing characteristics such as hardness, strength, ductility and machinability. From a metallurgical perspective, steels generally contain up to approximately 2.1% carbon; above this level, iron-carbon alloys are generally classified as cast irons.
In addition to carbon, steel may contain elements such as chromium, nickel, manganese, molybdenum, vanadium and silicon, which are used to obtain specific properties.
The English word steel has Germanic origins and is related to Old English stȳle and stēli, terms historically associated with the material and with objects made from hardened steel.
The material we now call steel was known and worked long before the modern English term and modern metallurgical definitions developed.
Origins: from iron to the first steels
The history of steel is closely connected with that of iron.
The earliest evidence of iron use dates back several thousand years. Initially, humans also used iron from meteorites, which could be found in metallic form and worked directly. Only later did people learn to extract iron from ores found in the earth, developing the first metallurgical techniques.
From the 1st millennium BC onwards, the use of iron became increasingly widespread among many civilizations, eventually characterizing the period commonly known as the Iron Age.
Early processes did not allow precise control over the composition of the material. However, heating and working iron in contact with carbon-rich materials could increase the carbon content of its surface and produce harder material: early forms of what we would now classify as steel.
Ancient and medieval world
Over the centuries, production techniques continued to evolve in different parts of the world.
Particularly significant were steels produced in India and the Middle East, including the so-called wootz steel, renowned for its properties and historically associated with the famous Damascus blades.
Steelmaking techniques also gradually improved in Europe during the Middle Ages. However, control over composition remained limited, and producing large quantities of steel with consistent properties was difficult and expensive.
For a long time, steel was therefore mainly used for applications in which hardness and strength were particularly important, including weapons, tools and working implements.
The Industrial Revolution
The major transformation took place between the 18th and 19th centuries, alongside the Industrial Revolution.
Increased iron production, the development of blast furnaces and a better understanding of metallurgical processes created the conditions for steel to be produced in much larger quantities.
A major breakthrough came in 1856, when Henry Bessemer patented the process that bears his name. The Bessemer converter used air blown through molten pig iron to reduce its carbon content and remove other impurities.
The process made it possible to produce large quantities of steel much faster and at a lower cost than previous methods.
Other systems were subsequently introduced, including the Siemens-Martin open-hearth process, allowing greater control over steel production and composition.
Steel and the rise of industrial society
Between the second half of the 19th century and the 20th century, steel became one of the defining materials of industrialization.
The availability of a strong, relatively inexpensive material that could be produced on a large scale supported the development of railways, bridges, ships, buildings, machine tools and industrial infrastructure.
Steel also played a fundamental role in the growth of the automotive industry and, more broadly, in the development of modern mechanical engineering.
The ability to modify its chemical composition and apply different heat treatments progressively made it possible to develop steels designed for increasingly specific applications.
The development of stainless steel
Another important milestone came in the early 20th century with the development of stainless steels.
The addition of a sufficient amount of chromium allows a thin passive layer of chromium oxide to form on the surface of the steel, helping to protect it against corrosion.
Following experiments and developments during the first decades of the 20th century, stainless steels rapidly spread across many sectors, from the food and chemical industries to medicine, architecture and mechanical engineering.
Today, numerous families of stainless steel are available, each developed to meet different operating requirements.
The development of case-hardened steels
Even in ancient times, people had observed that heat could modify iron and make its surface harder, particularly when the metal was heated in contact with carbon-rich materials. Over the centuries, these early observations contributed to the development of carburizing, a process that enriches the surface of steel with carbon.
With the development of industrial steelmaking between the late 19th and early 20th centuries, steels suitable for this treatment were developed with a relatively low carbon content, allowing them to retain a tough core while achieving a hard surface after treatment.
20MnV6 is the steel used by Sibo for its standard bushings. After carburizing and hardening, it can achieve a very hard surface with high wear resistance while maintaining a tough and impact-resistant core.
This combination represents the fundamental principle of case hardening: a hard, wear-resistant surface combined with a tough core capable of withstanding mechanical loads and impacts.
How steel is produced today
Modern steelmaking mainly follows two major production routes.
The first starts with iron ore, which is processed through a series of metallurgical operations to produce pig iron and subsequently steel.
The second makes extensive use of steel scrap, generally melted in electric arc furnaces. This allows existing steel to be recovered and returned to the production cycle.
Once the liquid steel has been produced, its chemical composition is carefully controlled and adjusted. The material is then cast and subsequently transformed through processes such as rolling, forging and drawing, depending on the required final product.
Main types
There is no single type of steel. By varying its chemical composition, microstructure and treatments, steels with very different characteristics can be produced.
In general terms, the main categories include carbon steels, alloy steels and stainless steels, alongside numerous grades developed for specific industrial applications.
Heat and thermochemical treatments also play a fundamental role, making it possible to modify the microstructure and properties of the material.
Processes such as hardening, tempering, quenching and tempering, and carburizing can provide different combinations of surface hardness, mechanical strength, toughness and wear resistance.
The choice of the most suitable steel therefore depends on the properties required for the component and its specific operating conditions.
Steel bushings catalog
Sibo manufactures standard and custom steel and stainless steel bushings, selecting materials and specifications according to wear resistance, mechanical requirements and operating conditions.
Contact us for technical informatioform n or a customised quotation, or request our steel bushings catalogue using the below.
