Believe it or not, the expression “stronger than steel” did not become a common phrase simply because it rolls off the tongue nicely. Rather, whatever it is you are comparing to this metal alloy is probably pretty darn tough.
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Made from the combination of iron and carbon, and other elements, steel is one of the world’s most utilized materials. From our simplest tools to our most complex structures, it is everywhere around the globe - surrounding and impacting us daily.
Yet, for playing such an important role in our society, knowledge about this common material is pretty uncommon.
So, exactly what is steel? And why is it so important?
What is Steel?
Metals, steels, they’re all the same, right? Well, not quite.
To be accurate, metals are natural elements found within the Earth’s crust. Think way back to high school chemistry and the metals on the periodic table, such as copper, zinc, and iron. If you remember, steel was not included.
This is because steel classifies as a variation of metal. Specifically, it is known as an alloy of iron. This means that its chemical makeup is actually a mixture that is part metal (iron) and part nonmetal (carbon).
At its core, you can think of steel as a purified form of iron. It retains iron’s metal characteristics but has a carbon content that ranges anywhere between 0.02% to 1.7%. Additionally, metal and non-metal elements are often added during the production process.
The addition of specified amounts of carbon and other alloying elements increases the physical-chemical properties such as strength, resistance, and variability. These drastic improvements make steel one of the most widely used materials in the world.
How is Steel Made?
Okay, so steel is basically iron with carbon and some other elements sprinkled in— great. But how in the world do we go from a rock in the ground to the finished product?
Well, today there are two primary ways steel is produced: the BOS (Basic Oxygen Furnace) method or the EAF (Electric Arc Furnace) method.
The BOS method stems from the original Bessemer Process (the first inexpensive industrial process for the mass production of steel) and uses raw material inputs to create steel.
In the BOS method, iron is smelted from its ore in a blast furnace and is reprocessed by blowing oxygen through the heated iron. The oxygen lowers the carbon content and reduces impurities within the iron, converting it into molten steel.
Unlike the BOS method, the EAF method takes a more modern approach and operates using recycled scrap steel--steel already produced and ready to be recycled. Rather than using raw materials like iron ore, recycled steel is fed through high-power electric arcs and melted into high-quality steel.
Initially, the BOS and EAF methods differ, but both produce the same end result: molten steel.
Once the molten steel is produced, it must be treated with a secondary steelmaking process that adjusts the steel's composition. This involves adding or removing certain elements and/or tweaking the temperature and production environment.
Once the final composition is chosen, it is time for the manufacturing, fabrication, and finishing stages. This involves techniques such as cold rolling, coating (galvanizing), or heat treatment (tempering) that give the steel its final shape and properties.
Types of Steel
There's a reason Superman was nicknamed the "Man of Steel" - steel is strong. But aside from its immense strength, steel's second greatest quality is versatility.
During the production process, different types of steel are created and categorized by their physical, chemical, and environmental properties. These properties include the amount of carbon, the level of impurities, and the addition of other alloying elements.
Each type of steel allows for different uses and applications and is broken down into four different groups by the chemical structures and physical properties:
1. Carbon Steel
Carbon steels contain trace amounts of alloying elements such as manganese, silicon, and copper. They are often dull and matte in appearance and account for 90% of total steel production. There are three sub-groups that categorize carbon steels based on their carbon content:
- Low Carbon Steel: contains less than .3% carbon and is the most common carbon steel.
- Medium Carbon Steel: contains between .3%-.6% carbon and often has manganese added.
- High Carbon Steel: contains 1.5% carbon and is the strongest of the carbon steels.
2. Alloy Steel
Alloy steels contain varying amounts of alloying elements (e.g., aluminum, chromium, copper, manganese, nickel, silicon and titanium). These additional elements change the steel's properties. Some examples of these properties include corrosion resistance, strength, or ductility. These steels tend to be cheaper and are often used in auto parts, mechanical work, power generators, and pipelines.
3. Stainless Steel
Stainless steels have a low carbon content and typically contain between 10%-20% chromium. They are commonly found in home appliances, food processing equipment, and kitchen utensils because of their strength and resistance to both corrosion and high temperatures.
4. Tool Steel
Tool steels contain varying amounts of cobalt, molybdenum, tungsten, and vanadium which make them extremely hard, durable, and heat resistant. These steels are ideal for making metal tools (hence their name) and are ideal for drilling, cutting, and stamping.
Why use Steel?
By now, you should have a solid idea of what steel is and how it's made, but here comes the big question: why do we use it?
Steel is a strong, durable, and versatile material, but it also has another key trait: sustainability.
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Steel is the most recycled material on earth and can be recycled an indefinite amount. This is because it does not lose any of its attributes during the recycling process.
Combining its sustainability with its strength and versatility makes steel not only one the most valuable resources in the world, but also the most utilized across countless industries.
From the construction of buildings, stadiums, and bridges to our automobiles, pipelines, farm equipment, and tools, steel is everywhere and contributes to both the development of our society and the betterment of our lives.
The steel industry in the US is an ever-evolving sector of the economy, with steel being a key component in many industrial products. From automobiles to bridges and buildings, it is an important part of the US steel industry. Industrial steel, in particular, is used in a wide variety of industries and applications due to its strength and durability. Its versatility makes it a popular choice for many projects, from construction and engineering to agricultural applications. The steel market is an integral part of the US economy and is here to stay.
Introduction
The iron and steel industry is an economic sector dedicated to the extraction, processing and transformation of iron into its various types of alloys, with steel being the most widely used for global development, due to its high demand by large key industries such as construction, transportation and machinery manufacturing.
Through high-performance processes, such as the reduction of iron ore in blast furnaces and refining in steel mills, steelmaking allows the production of materials with optimum mechanical properties, adapted to different technological applications.
Steel’s versatility and strength make it an irreplaceable resource in modern infrastructure, from buildings and bridges to transportation and energy systems. Thus, the steel industry drives innovation in materials engineering, playing a strategic role in the sustainability and efficiency of industrial processes.
What is the steel industry?
The steel and iron industry is the sector that specializes in the production of steel from the processing of iron ore and other ferrous materials. The obtaining of this resource includes processes such as extraction and preparation of the ore up to its transformation. Through stages such as smelting, refining and alloying, steels with specific properties are obtained that meet the standards of strength, durability and versatility required in different industrial applications.
This industry is important for infrastructure, machinery manufacturing and the development of strategic sectors such as transportation and energy. The quality of the steel produced depends on the purity of the iron ore used, where factors such as sulfur and phosphorus content influence its mechanical characteristics. Its global impact positions it as a fundamental pillar of the economy and modern engineering.
How does the steelmaking process work?
Due to its great importance, this process involves several key stages, each with a specific purpose to transform the raw material into high quality steel. Among the stages of the steelmaking process we have:
- Obtaining and preparing iron ore: The main raw material is iron ore, which is extracted in the form of oxides or carbonates. To improve its efficiency in the reduction processes, the ore is subjected to treatments such as sintering or pelletizing, which allows for more efficient handling and greater reactivity in the blast furnace.
- Ore reduction in the blast furnace: In integrated steelmaking, the reduction of iron ore is carried out in a blast furnace, a vertical reactor where the oxides are removed from the ore by reacting with carbon monoxide (CO) generated by the combustion of coke. This process results in pig iron, an iron with a carbon content of 4-5%, which is obtained in a liquid state together with the slag, which is removed periodically.
- Pig iron desulfurization: Before being converted into steel, pig iron undergoes a desulfurization process, where its sulfur content is reduced to improve its mechanical properties. This treatment is carried out by adding reagents such as lime and magnesium, which remove the sulfur in the form of slag.
- Conversion of pig iron into steel:
There are two main methods for converting pig iron to steel:
- LD (Linz-Donawitz) furnace conversion: Oxygen is added to the pig iron to oxidize the carbon and remove impurities such as silicon, manganese and phosphorus.
- Electric arc furnace: It is used to melt scrap and iron pre-reduced products by means of an electric arc generated between graphite electrodes. This process achieves greater versatility in the composition of the steel and facilitates the recycling of ferrous materials.
- Steel refining and finishing: To obtain steels with specific characteristics, finishing processes are carried out, where the concentrations of alloying elements such as chromium, nickel or vanadium are adjusted; residual impurities are also removed by deoxidation and other metallurgical treatments.
- Steel casting:
Molten steel is solidified by different casting methods:
- Ingot casting: Poured into molds for subsequent rolling.
- Continuous casting: A solidified product is obtained in the form of billets or slabs, optimizing the efficiency of the process.
- Forming and finishing: Finally, the steel undergoes forming processes such as hot or cold rolling, drawing or forging, and surface treatments such as galvanizing or special coatings to improve its strength and durability.
Each of these stages is necessary for the production of steel with controlled mechanical and chemical properties, adapted to different industrial sectors.
Types of steel and their industrial applications
Depending on their composition and characteristics, there are different types of steel, each designed for specific applications in various industries.
Carbon steel: It is an alloy composed of iron and carbon in a range of 0.3% to 2%, with minimal amounts of other elements. Its hardness and mechanical strength increase with carbon content, although it also reduces ductility and increases brittleness. It is more susceptible to corrosion compared to other alloy steels and is used in the manufacture of cutting tools, high-voltage cables, automotive parts and metal structures.
Alloy steel: It is obtained by adding elements such as nickel, chromium, copper and aluminum to the iron base, which gives it greater mechanical strength, hardness and tolerance to corrosion and high temperatures. Due to the variation in its composition, it adapts to different industrial needs, being used in engine parts, piping in the chemical industry, shipbuilding, marine structures and heavy machinery.
Tool steel: Incorporates tungsten, molybdenum, cobalt and vanadium to improve its hardness and wear resistance, even at high temperatures, making it an ideal material for the manufacture of drills, saws, milling cutters, molds for plastics, impact tools such as hammers and dies for metal stamping.
Stainless steel: Contains at least 10.5% chromium, together with nickel and molybdenum, which gives it high resistance to corrosion and chemical agents, as well as high cleanability. It is used in the manufacture of medical and surgical equipment, household appliances, kitchen utensils, architectural facades and in the food and chemical industries.
Corten steel: Corten steel is an alloy with copper, chromium and nickel, developing a protective oxide layer when exposed to the elements, which prevents deep corrosion. This type of steel is ideal for the construction of bridges, architectural facades, sculptures, urban furniture and maritime structures.
Galvanized steel: It is coated with zinc through a hot-dip process, providing high resistance to rust and corrosion, especially in outdoor environments. It is used in poles, metal fences, roofs, ventilation ducts and drainage systems.
Structural steel: Contains small amounts of manganese and silicon to increase its mechanical strength and capacity to support large loads without significant deformation. It is essential in the construction of skyscrapers, bridges, road infrastructure, electrical transmission towers and industrial platforms.
Surgical steel: It is a special type of stainless steel with a high content of chromium, nickel and molybdenum, which gives it biocompatibility, corrosion resistance and the ability to withstand sterilization processes without degradation. It is used in surgical and dental instruments, medical implants, prostheses, hypoallergenic jewelry and biomedical equipment.
Importance of the iron and steel industry
The iron and steel industry is a significant sector in the economic and technological development of any nation due to the production of steel, a key material in multiple industrial sectors. Its importance lies in the production of materials with high strength and durability, essential in the construction of infrastructure such as skyscrapers, bridges and railway networks, as well as in the manufacture of heavy machinery and precision tools. Without this sector, progress in engineering, transportation and manufacturing would be severely limited.
In addition to its relevance in construction and manufacturing, the steel industry drives the growth of other strategic sectors such as mining, energy and logistics, due to the high demand for raw materials and the transportation of derived products. It is also a key generator of employment, offering direct and indirect opportunities that strengthen economic stability and improve the quality of life of the population.
Unlike metallurgy, which encompasses various metals, the iron and steel industry specializes in the transformation of iron into steel, ensuring its optimization for different industrial applications. In this sense, the steel industry serves as a driver of industrialization, as well as a crucial element of global sustainability.
Future prospects for the iron and steel industry
In the coming years, several trends are expected in the sector, improving production efficiency, reducing environmental impact and adapting to new markets. Below are some of the main trends in the steel industry.
Sustainable production and green steel
Growing concerns about sustainability have led the steel industry to explore lower-carbon production methods. Green steel, produced with renewable energy sources and innovative technologies such as hydrogen-based steelmaking, is gaining prominence. This technique replaces carbon with hydrogen in the iron ore reduction process, virtually eliminating CO₂ emissions.
Development of high-strength low-weight steels
Advances in materials engineering have led to the creation of high-strength, low-weight steels, especially for sectors such as the automotive and aerospace industries. These materials make it possible to reduce the weight of structures without compromising their strength, improving energy efficiency and reducing emissions of polluting gases in vehicles and aircraft.
Recycling and circular economy
The use of recycled scrap in steel production is on the rise, aligning with the principles of the circular economy. This approach reduces dependence on virgin raw materials and significantly reduces energy consumption and pollutant emissions. Advanced technologies in steel recycling improve process efficiency and enable the reuse of materials with a lower environmental impact.
Nanotechnology applications in steel
Nanotechnology is currently synthesizing steels with improved properties, such as increased corrosion resistance, greater durability and better mechanical behavior. These advances offer opportunities for applications in extreme conditions, such as structures in marine environments or high-wear machinery components.
Conclusions
The iron and steel industry is an essential component of global industrial and economic development, providing materials with a unique combination of strength, durability and versatility. Its impact extends to key sectors such as construction, transportation and manufacturing, where steel is indispensable for the creation of high-performance infrastructure, vehicles and machinery. Thanks to its ability to adapt to different applications through refining and alloying processes, the iron and steel industry has been a driver of modernization in multiple industries.
In addition to its structural importance, the iron and steel industry represents a strategic axis in the circular economy, promoting recycling and the optimization of resources to reduce environmental impact. With the advance of new technologies, such as hydrogen-based steelmaking and the development of lighter and stronger steels, the industry is moving towards more sustainable and efficient production. In this context, its evolution will not only ensure the supply of essential materials, but will also contribute to meeting the environmental and technological goals of the future. Steelmaking will therefore continue to be a key pillar in the transformation of modern societies and in the construction of more sustainable development.
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