The magnetic properties of materials determine the possibility of their use in various technological processes and devices. In this article, we will consider the influence of the chemical composition and technological features of heat treatment on the magnetic characteristics of precision alloys. We will pay special attention to such structure-sensitive parameters as coercive force, magnetic induction, magnetic field strength, and hysteresis losses.

Properties of magnetic materials

The magnetic properties of precision alloys are determined by their chemical composition, manufacturing technology and heat treatment features. All the characteristics acquired by the alloy can be divided into two main groups:

• Structurally insensitive parameters — these include the phase transition temperature (Curie point), the maximum induction that can be obtained in a particular material (saturation induction), changes in the volume and linear dimensions of parts depending on their magnetization (magnetostriction). These properties depend on the chemical composition and structure of the alloy and can be adjusted by adding various impurities. The technological features of production and heat treatment have little effect on the listed characteristics.
• Structurally sensitive parameters is the intensity of the external magnetic field that is necessary for complete demagnetization of the material (coercive force), power loss when the core is magnetized and demagnetized when current flows (hysteresis losses), and a coefficient characterizing the relationship between magnetic field strength and magnetic induction (magnetic permeability). These characteristics are significantly affected by heat treatment and the method of producing the material, as well as the presence of harmful and useful impurities. The effect of impurities is due to the fact that when impurity atoms are introduced, the electron density in the crystal lattice is unevenly distributed, and this leads to a change in magnetic properties.

Using various methods of heat treatment, it is possible to significantly change the structure-sensitive parameters of precision alloys. For example, the magnetic permeability of the material can be increased or decreased in this way by about 20 times.

The effect of carbon and other impurities on the magnetic properties of alloys

Carbon It is considered one of the most “influential” impurities. A decrease in the amount of this chemical element reduces specific losses and increases the magnetic induction of materials, and an increase in its content worsens the magnetic properties of alloys. The figure shows the effect of carbon impurities on iron magnetization curves.

Nitrogen has a more significant effect on the magnetic properties of alloys: even with a slight increase (by 0.005-0.01%) in the percentage of this substance, the coercive force can increase several times. Also, the coercive strength of materials increases significantly when the amount of sulfur increases, and slightly when phosphorus, oxygen or manganese is present. That is why precise chemical composition and strict chemical composition are so important for precision alloys overseeing quantities harmful contaminants in alloy after production.

The role of heat treatment in the formation of the magnetic properties of precision alloys

Mechanical stresses caused by various machining processes, such as rolling and forging, make significant changes in magnetic properties. Internal stresses can prevent magnetization, which leads to an increase in coercive force and a decrease in magnetic permeability.

Heat treatment, such as annealing, plays an important role in restoring magnetic properties after machining. This process helps to relieve internal stresses and create an optimal microstructure of the crystal lattice.

For soft magnetic materials, characterized by low coercive force, the homogeneity (homogeneity) of the structure and the absence of internal stresses are important. For magnetic-hard alloys, where high coercive force is required, hardening is used to create magnetic anisotropy — the dependence of magnetic parameters on the direction of magnetization.

Thus, composition control and the use of various methods of mechanical and thermal treatments play a key role in creating magnetic materials with certain parameters. Understanding the influence of each stage on magnetic properties makes it possible to develop materials with optimal characteristics for specific technological problems.

PZPS products: basic magnetic materials

The St. Petersburg Precision Alloy Plant produces a range of magnetic materials, including those with high magnetic permeability, high saturation induction, a rectangular hysteresis loop and high magnetostriction. The plant's products include alloys of the following grades:

• 50NP and 70NM with a rectangular hysteresis loop;
• 45N and 50N with increased saturation induction and high magnetic permeability;
• 79NM, which has the highest magnetic permeability in magnetic fields;
• 49K2FA with high saturation induction;
• 49K2F with high magnetostriction.

To order an alloy with the required magnetic parameters or select the optimal material for your project, leave a request on the website or call specified phone. Our experts will answer all your questions in detail and help you find the most suitable precision alloy.

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