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Why steel ist not just steel

Do you also prefer to go shopping where the selection is greatest? Then we have good news for you. Worldwide there are over 2,500 standardized types of steel and a large part of this is processed at Walzwerke Einsal.

At this point we already hear the objections: “2,500 varieties, how can that be? Isn't steel simply the combination of iron and carbon from which its impurities have been expelled? Steel is steel! "

Well, that may have been the case in the 14th century, when the first blast furnaces were built in Europe, but a lot has happened in the last 700 years. In fact, the production of steel as part of metallurgy has meanwhile become a science of its own.

Nowadays there are countless manufacturing processes in which the addition of additional alloying elements and the heat treatment process used, play a decisive role. Because this makes it possible to produce steel with a wide variety of material properties: hardness, tensile strength, oxidation or corrosion resistance, for example, can be precisely balanced in the production process.

In this way, types of steel are created that are ideally suited for their intended use - and that is over 2,500. And we would like to present our three most important categories to you in more detail below.

The tough one: Nickel-based materials

The element nickel - element symbol: Ni, atomic number: 28 - is a real miracle weapon as a metal. At 1,455°C it has an extremely high melting point, it is particularly resistant to chemical substances, very resistant to oxidation, as only one of three elements is ferromagnetic - and therefore quite expensive. For a ton of nickel (as of February 2021) you have to put around 15,000 euros on the table.

So it's good that nickel passes on its excellent properties in alloys to other metals; for example our nickel-based materials. In particularly high concentrations, the nickel content can reach over 50 percent, but even in smaller amounts, nickel makes a steel alloy corrosion-resistant, insensitive to constantly high temperatures - experts also call this creep-resistant - and increases the toughness and tensile strength of the material.

A particularly extreme example of a nickel-based material is the superalloy called Alloy 718. It is creep-resistant up to 700°C, oxidation-resistant up to 1,000°C and has a nickel content of 52.5 percent. It is used wherever the material is exposed to extreme conditions. For example in the turbines of aircraft.

It should also be mentioned that nickel always forms the main component of a nickel-based alloy, although numerous other elements are necessary for the production of modern materials. Alloy 718 already mentioned, for example, still contains 19 percent chromium, 3 percent molybdenum, 0.9 percent aluminum, less than 0.1 percent copper, 5.1 percent niobium and 0.9 percent titanium. As I said: steel production is a science in its own right.

If you want to delve deeper into the subject: The composition of common nickel-based materials is described in DIN 17742, DIN EN 10095, ASTM B168, the material-specific AMS standards for the aviation industry and many other regulations

Whatever the composition of a nickel-based alloy may look in detail, its possible uses are extremely versatile. Nickel alloys are used wherever harsh conditions prevail and materials have to be resistant. These are:

  • Mechanical stress: The effect of constant forces and strong moments.
  • Chemical stress: attacks of a chemical and electrochemical nature on the surface.
  • Thermal stress: the effect of constant as well as abruptly changing temperatures.

Nickel-based materials are therefore used in numerous areas, for example in the chemical industry, aerospace technology, automobile construction and medical technology.

The light one: Titanium-based materials

Titanium - element symbol: Ti, atomic number: 22 - has outstanding properties as a metal. It is characterized in particular by its high tensile strength and the natural formation of a protective layer that makes it insensitive to external influences. At the same time, it has a density of just 4.5g/cm3 (for comparison: the density of iron is 7.8g/cm3) and is therefore comparatively light.

Unfortunately, it is also comparatively expensive - very expensive to be precise. A ton of pure titanium costs more than 100.000 euros. This enormous price is not justified by the rarity of the element; in fact, titanium is the ninth most abundant element on our planet. However, the metal is almost never found in its pure state and must first be extracted using extremely complex and expensive processes.

To give you an impression: The production of one kilogram of cement consumes an average of 0.3 kilowatt hours of energy. One kilogram of steel accounts for six kilowatt hours, and one kilogram of plastic even with 19 kilowatt hours.
For one kilogram of titanium, however, 140 kilowatt hours of energy are required - for the same amount an energy-saving lamp could light up for a year and a half or 5,000 cups of coffee could be brewed.

Once extracted, an alloy with titanium gives the steel high strength, toughness and fracture resistance, known in specialist circles as ductility. Due to the already mentioned tendency to form an oxidative protective layer, it is also particularly corrosion-resistant and at the same time lighter than other alloys due to its low density. The metallurgy distinguishes between different grades, classified from 1 to 39. The grades 1 to 4 denote pure titanium in different purities, the grade 5 material most frequently used in industry has a titanium content of 90 percent.

These titanium alloys are therefore used wherever it is not just about the durability of the material, but especially where every gram counts. For example, titanium elements are installed in spaceships, are part of protective equipment for the military and police, or are used in medicine for the manufacture of modern prostheses.

But titanium materials are also finding their way into our normal everyday life. In sports equipment such as golf and tennis rackets, bicycles or mountaineering equipment, the ultra-light material ensures higher performance. And with high-end technology for notebooks and smartphones, a housing made of a titanium alloy protects sensitive components.

The versatile one: Inox

Inox is highly resistant to corrosion and high temperatures. This type of steel is popularly referred to as stainless steel.

However, this cannot do without a certain alloying element. This time, in addition to the nickel already mentioned, it is first of all chromium: Element symbol: Cr, atomic number: 24. As a raw material, it is extremely rare on our globe in unbound form. Only ten deposits at great depth have been discovered so far. However, it is often found in connection with other elements, for example as ferrochrome, an alloy of iron and chromium. In this form, chrome is not only relatively cheap at around 200 euros per ton, it is also ideally suited for the production stainless steels.

But the addition of chrome doesn't just make the material resistant to rust, heat and acid. Steel also gains other properties through a chrome alloy. For example, the metal makes it very easy to shape and thus enables numerous possible uses. In addition, chrome alloys are characterized by their low thermal conductivity - which makes them ideal for a wide variety of applications.

Here, too, it goes without saying that chromium is only one of numerous alloy elements for stainless steel. Different materials require a wide variety of metals - depending on the desired material properties and the intended use. Another example of a typical Inox alloy element would be molybdenum, element symbol Mo, atomic number 42.

This heavy metal from the chromium group has only been known to mankind since the 18th century and is now mainly obtained as a by-product in copper production. Solid molybdenum, on the other hand, is very rare. So far, in addition to a rock sample from the interior of a volcano, it could only be detected in three soil samples that were brought from the moon by US astronauts.

Metallurgists discovered its usefulness in steel alloys towards the end of the 19th century. In small quantities, it is used there for hardening on the one hand, and to increase chemical resistance on the other.

Overall, Inox is used almost everywhere thanks to its high resistance, its excellent further processing properties and the good price/performance ratio. You can find it in your bathroom fittings and cutlery, in the pharmacy and in the kettle of your favorite brewery, in your garden fence and the stairs of your local outdoor pool.

We'd miss steel

Researchers believe that the ancient Egyptians were the first to process ferruginous meteorite rocks more than 5,000 years ago. Since then, our material has come a long way. Today steel is a high-performance material with numerous important properties, without which our modern world would simply be inconceivable.

We hope to have brought you a little closer to its diversity and to have given you a little insight into how much intelligence, effort and science actually goes into steel production. Because steel is never just steel, but must be produced precisely and with the greatest care for its future application.

That is precisely why we at Einsal are proud of our know-how and the consistently high quality of our steels - from the superalloy for the intercontinental aircraft to the chrome steel for the thermos flask. If you, too, are convinced of our services or simply have a question, please do not hesitate to contact us. In any case, we look forward to hearing from you.