Alloyed and non-alloyed steels: what they are and what are their applications.

Deciphering the World of Steels: A Complete Guide

In the fascinating world of metallurgy, steels occupy a prominent place due to their versatility and diverse applications. To better understand this universe, it is crucial to approach its classification from two key perspectives: chemical composition and specific applications. Join us on this journey to explore the different facets of steels!

Classification by Chemical Composition: Alloyed and Non-Alloyed

Steels can be divided into two main categories based on their chemical composition: alloyed and unalloyed. This distinction is fundamental as it directly affects the properties and performance of the steel in various applications.

Non-alloy steels are composed mainly of iron and carbon, with minimal amounts of other elements considered residual.

Alloy steels contain additional elements apart from iron and carbon, which can be both metals and non-metals. These added elements are used to modify and improve  properties of steel, such as mechanical strength, hardness, machinability  </ span>or corrosion resistance.

The symbolic designation of steels, which is based on their chemical composition, is essential to properly identify and classify materials, facilitating their selection and application in various industries.

Limit contents of residual elements for the Classification of Steels

To classify steels as alloyed or non-alloyed, the table containing the limit content of each chemical element in % is used as a reference.

To avoid the joint effect of some elements when their presence is close to the maximum content, two groups have been selected and appear in the table as (1) and (2). In both cases, it must be met that none of them exceed the established limit and that the sum of the content of the elements present in the group is less than 70% of the sum of the individual limits.

Limit contents for the Classification of Steels

It is important to take into account the limit contents of certain elements in steels, since these can influence their properties and performance. For example, the presence of elements such as chromium, nickel, and molybdenum can improve the corrosion and temperature resistance of stainless steels.

When analyzing the chemical composition of steels, it is essential to consider the interactions between the different elements to guarantee quality and compliance with the specific standards of each application.

 (1) When two, three or all four of these elements are found in combination in a steel, the following must be considered simultaneously: a) the individual limit percentages of each of them, b) a joint limit content that will be 70% of the sum of the values. individual limits of each of the elements considered. (2) When two or three of these elements are found in combination, the same rule applies as for elements marked with (1)

Classification by Specific Applications

In addition to classification by chemical composition, steels are also classified according to their specific applications. This classification considers the properties and characteristics required for different industrial and commercial uses. Some of the most relevant categories include:

• Structural steels: Designed to support structural loads in buildings, bridges, and other infrastructures.
• Special steels for mechanical construction: Used in the manufacture of components and machinery that require high resistance and toughness.
• Stainless steels, valves and refractories: With resistance to corrosion and high temperatures, ideal for applications in aggressive environments.
• Steels with specific properties and applications: Adapted for particular needs, such as wear resistance, thermal conductivity, etc.
• Special steels for tools and tools: Designed for cutting tools, dies, dies and other applications that require high hardness and wear resistance.

Explore the fascinating world of steels and unlock their infinite potential in modern engineering and manufacturing!