Due to the dominant trends in the development of various industries in recent decades, the demand for new magnetic materials has increased sharply. The need for them increased around the mid-1990s and continues to grow. Transformers, magnetic amplifiers, rotors and stators of electrical machines, and much more — all this requires components that are made from soft magnetic alloys. So what is this?
It is known from a high school physics course that the magnetic properties of all materials make them react to a magnetic field in one way or another. In the world around us, most materials are diamagnets or paramagnets, meaning they hardly react to magnetic fields. However, there are also so-called ferromagnets — materials that can be magnetized under the influence of an external magnetic field and partially or completely retain the acquired magnetization after removal from it. First of all, these are metals: if you run a permanent magnet over a nail or screwdriver, these objects will temporarily become magnetized and will emit their own weak magnetic field.
The most common ferromagnets are iron, cobalt and nickel, but we rarely encounter chemically pure substances in everyday life. In the manufacture of metal products, special alloys are usually used to give the metal the desired properties — sensitivity, wear resistance, and so on. Thus, compounds based on iron, cobalt or nickel with the addition of manganese, silicon, aluminum and other materials are capable of producing various types of precision alloys that demonstrate ferromagnetism and have specified parameters.
Depending on the ease of magnetization, ferromagnets are divided into magnetic-solid et magnetically soft. Soft magnetic materials (like alloys made from them) are easily magnetized, but this magnetism is usually temporary. Magnetic solids, on the contrary, are difficult to magnetize, but after that they retain their magnetism.
Products made of precision soft magnetic alloys have high strength and sufficient plasticity, withstand high current strength, temperature coefficient of linear expansion, and have good magnetic properties. Such characteristics are necessary for the manufacture of particularly sensitive elements and high-precision devices. Computers, microphones, walkie-talkies, antennas, microscopes and many other items important to us would not be able to fully perform their functions without using various types of soft magnetic alloys in their manufacture.
Each brand is used to produce products with different properties. For example, 50NHS alloys are used in the cores of communication equipment for throttles and pulse transformers, 49K2F alloys are used in ultrasonic, hydroacoustic equipment, electromechanical filters, delay lines, and 49K2FA in telephone membranes.
To decipher the alloy grade, you need to know what letters are used to designate certain chemical elements that make up the product. If the letter A is at the very end, it means that it is high-quality steel, its phosphorus and sulfur content is kept to a minimum, and all the conditions for high-quality metallurgical production are met. The two letters A at the very end indicate that this steel grade is extremely pure, that is, there is practically no sulfur and phosphorus in it. Regular quality steels are marked with the letters “t” and numbers 0 to 6, which indicate the grade number depending on its chemical composition and mechanical properties.
Steel grade 79NM means that the metal alloy is based on nickel (Ni) and its content can range from 78.5% to 80%. And in grade alloy 50N nickel — from 49% to 50.5% (that is, in this case the letter H stands for nickel).
It is not necessary to memorize all alphanumeric designations — to clarify information on a specific steel grade, you can use so-called maraudersthat are easy to find on the Internet.
