A magnetic material with low coercivity and high permeability. Soft magnetic materials are easy to magnetize and demagnetize, and are widely used in electrical and electronic equipment. The most commonly used soft magnetic materials are iron silicon alloys (silicon steel sheets) and various soft magnetic ferrite materials. There are various types of soft magnetic materials, usually divided into:

① Pure iron and low-carbon steel. Carbon content below 0.04%, including electromagnetic pure iron, electrolytic iron, and carbonyl iron. It is characterized by high saturation magnetization, low price and good processing performance; But its low resistivity and high eddy current loss under alternating magnetic fields are only suitable for static use, such as manufacturing electromagnetic iron cores, pole shoes, relay and speaker magnetic conductors, magnetic shielding covers, etc.

② Iron silicon alloy. The silicon content ranges from 0.5% to 4.8%, commonly known as silicon steel sheet, and is generally used as a thin plate. Adding silicon to pure iron can eliminate the phenomenon of magnetic materials changing with usage time. With the increase of silicon content, the thermal conductivity decreases, the brittleness increases, and the saturation magnetization decreases, but its resistivity and permeability are high, and the coercive force and eddy current loss are reduced, which can be applied to the AC field to manufacture iron cores for motors, transformers, relays, transformers, etc.

③ Iron aluminum alloys. Containing 6% to 16% aluminum, it has good soft magnetic properties, high permeability and resistivity, high hardness, good wear resistance, but brittleness. It is mainly used for manufacturing iron cores and magnetic heads for small transformers, magnetic amplifiers, relays, and ultrasonic transducers.

④ Iron silicon aluminum alloy. Obtained by adding silicon to a binary iron aluminum alloy. Its hardness, saturation magnetic induction intensity, magnetic permeability, and resistivity are all high. The disadvantage is that magnetic properties are sensitive to component fluctuations, have high brittleness, and have poor processing performance. Mainly used for audio and video heads.

⑤ Nickel iron series alloys. Nickel content is 30%~90%, also known as permalloy. Through alloying element ratio and appropriate process, magnetic properties can be controlled to obtain soft magnetic materials such as high magnetic conductivity, constant magnetic conductivity and moment magnetic conductivity. It has high plasticity and is sensitive to stress, and can be used as a material for pulse transformers, inductor cores, and functional magnetic materials.