Fundamentals of materials science: chemical composition, structure and properties

Materials science is a science that studies the relationship between the chemical composition, structure and properties of materials, as well as their changes under the influence of various external factors.

The main task of materials science is to find the optimal combination of the chemical composition of the material and the method of its processing to achieve specified properties, for example, increased strength or plasticity, high electrical conductivity and other properties. This is important for various areas, from the production of metal alloys to the creation of polymers and composites.

Materials science covers all types of materials, including metals, alloys, polymers, glass, ceramics, and others. An important branch of this science is metal science, which focuses on studying the relationship between the chemical composition, structure and properties of metals and metal alloys exclusively.

The chemical composition of the metal

The chemical composition of a material is the percentage of chemical elements present in it. It is he who determines the basic properties of materials. This is especially important in production precision alloys, where the accuracy of the chemical composition plays a key role. After all, even small changes in the content of the elements can significantly affect the final characteristics of the product.

On PZPS a spectral laboratory operates that accurately determines the chemical composition of alloys at each stage of the process, which ensures high quality of our products.

Metal structure

The structure includes complete information about the material under study: from the electronic structure of individual atoms to surface defects visible to the naked eye.

When studying the structure of the material, there are:

• macrostructure study — allows you to identify defects (chips, cracks, pores, shells, etc.) visible to the naked eye and when magnified by no more than 10 times (magnifying glass);
• microstructure analysis is the determination of the location of particles that can only be seen at high magnification using an optical (up to 1,000 times) or electron (up to 25,000 times) microscope.

At the same time, materials can, having the same chemical composition, have different structures and, as a result, different properties.

Various methods are used to study the structure:

• X-ray analysis is based on the fact that, passing through the normal structure of the metal or existing defects, X-rays are weakened in different ways;
• magnetic and ultrasonic flaw detection — distortion of the intensity of the magnetic field and ultrasonic waves makes it possible to detect internal and external defects in the structure;
• capillary flaw detection — using special liquids, it allows you to detect thin cracks on the metal surface that are invisible to the eye.

For controls structures of steels and alloys, a metallographic laboratory operates at the PZPS. In particular, it evaluates non-metallic inclusions and grain score, which helps to accurately determine the properties of products.

Material properties

The properties of materials can be influenced both through their chemical composition and by changing their structure during various types of processing.

For example, when the quantity decreases carbon in steel, its strength decreases, but plasticity increases. As the amount of carbon increases, casting properties improve, but ductility and weldability are getting worse. The addition of silicon increases the elasticity of the alloy, and manganese increases its strength.

Pressure treatment has a special effect on the properties of metals, since this effect forms a rivet — grain deformation, as a result of which the strength and hardness of steel increase. It is possible to remove this condition or make other changes to the internal structure of the material by heat treatment: annealing, hardening and tempering.

• Annealing involves heating the material to a certain temperature, then holding it and slowly cooling it (together with the furnace). It makes steels and alloys less hard and improves their workability, as well as relieves internal stresses.
• Hardening is heating the material to a certain temperature, holding it at this temperature and then rapidly cooling it (into water, oil or other quenching media). It increases the strength and hardness of the material, but reduces its plasticity and viscosity.
• Tempering is the heat treatment used after the material has been hardened. Its goal is to obtain a more balanced structure of steel or alloy, to relieve internal stresses after hardening.

As a result heat treatment it is possible to completely change the mechanical properties of steel or alloy: by hardening and annealing, two materials with significant differences in hardness, viscosity and plasticity are obtained.

Materials science is a key discipline for engineers and manufacturers that allows them to create materials with the required characteristics. By controlling the chemical composition and structure, as well as understanding the impact of various processing methods, it is possible to achieve optimal properties of steel or alloy while maintaining high quality and production efficiency. At the PZPS you can order material with exactly the properties that your production needs, and be confident in the quality of the product.