Magnetic field permanent magnet manufacturers tell you that steel or other materials can become permanent magnets because they are properly treated and processed, and the internal inhomogeneity is in the best state and the coercivity is the largest. Iron's crystal structure, internal stress and other inhomogeneities are small, and its coercivity is naturally small, so it does not require a strong magnetic field to magnetize or demagnetize it. Therefore, it cannot become a permanent magnet. Magnetic field permanent magnet manufacturers tell you that materials that are easy to magnetize and demagnetize are called "soft" magnetic materials. "Soft" magnetic materials cannot be used as permanent magnets, and iron belongs to this category of materials.

Just like the kind you usually see with magnetic steel rods. Permanent magnets are objects that retain a certain residual magnetization after the external magnetic field is removed. To make the residual magnetization of such an object to be zero and the magnetism to be completely eliminated, a reverse magnetic field must be added. The magnetic field permanent magnet manufacturer tells you the magnitude of the reverse magnetic field required to completely demagnetize the ferromagnetic substance, which is called the coercive force of the ferromagnetic substance.
Both steel and iron are ferromagnetic, but their coercivity is different. Steel has a larger coercivity, while iron has a smaller coercivity. This is because in the process of steelmaking, carbon, tungsten, chromium and other elements are added to the iron to make carbon steel, tungsten steel, chromium steel, etc. The addition of carbon, tungsten, chromium and other elements causes the steel to have various inhomogeneities at room temperature, such as inhomogeneous crystal structure, inhomogeneous internal stress, and inhomogeneous magnetic strength. Magnetic field permanent magnet manufacturers tell you that the unevenness of these physical properties increases the coercive force of steel. And the greater the degree of unevenness within a certain range, the greater the coercivity. However, these inhomogeneities are not the best state that the steel has or has achieved under any circumstances. In order to achieve the best state of the internal inhomogeneity of the steel, proper heat treatment or machining must be carried out. For example, when carbon steel is smelted, its magnetic properties are similar to that of ordinary iron; after it is quenched at high temperature, the non-uniformity grows rapidly and becomes a permanent magnet material. The magnetic field permanent magnet manufacturer tells you that if the steel is slowly cooled down from a high temperature, or the quenched steel is smelted at 600 or 700 degrees Celsius, its internal atoms will have sufficient time to arrange into a stable structure. The uniformity is reduced, so the coercive force is reduced, and it is no longer a permanent magnet material.