Description of the types of steel depending on their composition, quality and application according to UNE-EN 10020:2001. Steel types in industrial machining.

Steel types: by composition, quality and application

It is common to work with different materials in industrial machining, and steel is one of the most widely used. Steel is an alloy of iron (Fe) and carbon (C), which retains the metallic properties of iron in its pure state and, depending on the proportion of carbon and the treatments applied to it, we obtain different types of steel. The variety in the types of steel is related to different properties: hardness, corrosion, malleability, elasticity, ductility and resistance. These properties make steel an ideal quality material for industrial machining applicable to sectors such as food, agricultural machinery, renewable energies, railway constructions, the chemical and mechanical sectors, among others.

UNE-EN 10020:2001 Standard for the classification of steels

There is a wide variety of ways of identifying and classifying steels according to their composition, quality, intended use, etc., and each country has its own standards and regulations. UNE-EN 10020:2001 is the standard that regulates the classification of steels in Spain, although there are others with wide international application, such as the American AISI (American Iron and Steel Institute) and ASTM (American Society for Testing and Materials), the German DIN standards, or ISO 3506 and the EN 10025-2:2006 and EN-10025-4:2007 standards for structural steels.

The Spanish standard UNE-EN 10020:2001 classifies steels into different types:

1. According to chemical composition.
2. According to quality.
3. According to their application.
4. According to the numbering system of EN 10020 steels.

Types of steel according to their chemical composition and quality.

It is common to work with different materials in industrial machining, and steel is one of the most widely used. Steel is an alloy of iron (Fe) and carbon (C), which retains the metallic properties of iron in its pure state and, depending on the proportion of carbon and the treatments applied to it, we obtain different types of steel.

The variety in the types of steel is related to different properties: hardness, corrosion, malleability, elasticity, ductility and resistance. These properties make steel an ideal quality material for industrial machining applicable to sectors such as food, agricultural machinery, renewable energies, railway constructions, the chemical and mechanical sectors, among others.

Carbon or non-alloy steels

Non-alloy steels or carbon steels are those that contain other alloying elements such as manganese, chromium, nickel, vanadium, or titanium in smaller quantities. Furthermore, they can be low-carbon, medium-carbon or high-carbon steels, depending on their carbon content.

In terms of quality, they can be quality non-alloy steels, with special characteristics in terms of toughness, grain size or formability, or special non-alloy steels, which have a higher purity in the content of non-metallic inclusions and offer good values in their yield strength, hardenability, cold formability, weldability and toughness.

Alloy steels

Alloy steels are those which in their composition, in addition to carbon, have another element with a value equal to or greater than the limit value given in table 1 of UNE EN 10020:2001. They can be low or high alloy steels, depending on the greater or lesser presence of this element.

As far as the quality of the steels is concerned, and according to their behaviour in terms of toughness, grain size or formability, we have several types of alloy steels. Quality alloy steels, intended for metal construction, for flat products, rolled products, those with copper in their alloy, steels for electrical applications, etc. Special alloy steels have a precise control of their chemical composition, a particular processing and control to ensure improved properties, such as those intended for mechanical construction and pressure equipment, bearing steels, tool steels and high-speed steels.

Stainless steels

Stainless steels are those containing a minimum of 10.5% chromium and a maximum of 1.2% carbon, considering the chemical composition and quality. The quality of stainless steels varies according to their nickel content and to physical characteristics such as corrosion resistance, resistance to hot oxidation or their creep performance.

Most common steel types

The classification of steel types is very broad. There are different types according to their handling capacity, depending on the elements added to their alloy. Moreover, there are more than 5,000 different types of steels with different applications thanks to the development and innovation of the steel industry. The most common types of steel for industrial use include the following.

Corten steel

Corten steel is resistant to atmospheric corrosion thanks to the nickel, phosphorus, copper and chromium present in its alloy, which protect it against oxidation. Corten steel does not therefore lose its mechanical qualities. Its adaptability, strength and versatility make it suitable for use in the railway industry, building cladding, urban furniture, both indoors and outdoors.

Corrugated steel

t is a type of structural steel used in reinforced concrete structures. They are a kind of rolled bars that can be cut and bent with relative ease, as their main property is ductility.

Galvanised steel

The galvanisation process consists of bathing the steel in zinc to protect it from oxidation, this process gives it metallic strength and resistance to corrosion. It is used in furniture, building, agricultural and livestock industries.

Stainless steel

This is a type of alloy steel that must contain at least 10.5 % chromium and more than 1.2 % carbon, and may also contain other elements. Stainless steel is one of the most widely used because of its resistance to corrosion, oxidation, high temperatures, recyclability, durability, hardness and good aesthetic finish. It is used in constructions, buildings, in the food industry, household appliances, chemical and petroleum industries, among others.

Rolled steel

It is made from raw steel that is melted into ingots and deformed by heat into sheets until it forms the desired profile depending on its use. It is widely used in construction as it withstands heavy weights and is very resistant.

Carbon steel

This type of steel contains different proportions of carbon which define its mechanical properties, as well as other alloying elements. It has great strength, hardness and malleability, which is why it is used in construction, in the mechanical industry, shipbuilding or in the construction of commonly used elements such as bicycles or locks.

Alloy Steel

It contains various chemical elements and other components that improve its mechanical properties. Low alloy steels and high alloy steels depend on the weight of the alloying elements. The construction industry, aerospace, railways, land and maritime structural engineering are sectors where its application is common. 

Mild Steel

It has a low carbon content, is malleable and has low corrosion resistance. Mild steel is readily available, its price is not high, and its fabrication is one of the simplest, so it is widely used in the manufacture of internal components, where metal bending or welding is required.

Fizzing Steel

So called because in the manufacturing process it gives off small bubbles due to the effect of fermentation or deoxidation of the steel, a chemical process of eliminating excess oxygen from the molten metal. There are four different types within this category: dead, semi-dead, edged and capped steels. It is used to manufacture profiles, wires and thin sheet.

Cold Drawn Steel

It is manufactured at room temperature with additional pressure to give it shape, this gives the steel certain qualities such as strength, yield, allows for more precise measurements, sharper corners, and an aesthetic finish. It is used for machined parts, in the automotive industry, axles and fabricated structural units, hand tools.

Structural steel

Also known as construction steel, it is a material that has been heat-rolled and cold-formed, has high ductility and fracture toughness. It is used in the construction of all types of structures, buildings and for industrial machine components.

Weathered Steel

It has improved resistance to atmospheric corrosion, i.e. it develops an oxide layer on its surface on contact with rain and humidity, which adheres to the main metallic element, protecting it from subsequent corrosion and providing greater strength. It is used in the cement industry, in construction.

Mild Steel

There are various degrees of mild steel with a low carbon content. Other elements may be added to the alloy to improve properties such as corrosion resistance, wear resistance or tensile strength. This metal is highly machinable and offers improved weldability. It can be cut, machined and shaped into complex parts. Beams, nuts, bolts, screws are made from this type of steel.

Black steel

Black steel has a minimal carbon content and has not been subjected to other treatments, because of this its surface darkens. It is a strong and durable material used for the manufacture of tools, utensils, appliances, furniture and decorative elements.

What types of steel are used in industrial machining?

Steel is one of the indispensable metals in industrial machining. Among the most commonly used are carbon steels, alloy steels, stainless steels and tool steels, which offer advantages in terms of durability, toughness and performance. These characteristics make this material essential in the manufacture of parts and machinery for the food and agricultural sectors, in the manufacture of household appliances, the chemical industry, the oil industry and in the manufacture of moulds, among others.

EONSI specialises in the industrial machining of steel parts. We have the machinery and specialised equipment to work steels for machining for various industrial sectors. We manufacture elements with different types of steels with special characteristics of resistance to corrosion, high durability, resistance to high temperatures or ease of cleaning. Contact us and discover the advantages of steel machining with guaranteed quality.

Numbering of steel types in the UNE-EN 10020:2001 Standard.

The numbering system of the steel types according to the UNE-EN 10020:2001 Standard, follows the scheme 1. YY XX(XX).

• The number corresponds to the material group, in this case, 1. is for steels, for other materials it is used from 2 to 9. 
• YY is used to indicate the steel group number, specifying the main characteristics of the group and the tensile strength.
• XX(XX) is the sequence number, the digits in brackets are for possible future use.

The EN 10020 system classifies steel types according to their chemical composition (unalloyed and alloyed steels), and the quality category based on their main properties and applications.