Magnetic control of metal
This method of non-destructive testing is quite effective for determining the stresses in the metal. The metal magnetic memory method is based on the use of irreversible changes in the magnetic state of ferromagnetic materials in the zone of stress and strain concentration.
It has been established that the change in the residual magnetization of ferromagnetic materials is associated with the maximum acting stresses. In places of local change in magnetization, stray magnetic fields arise, which are recorded by appropriate instruments. Thus, we get a unique opportunity to find damage zones without careful preparation of the product surface by measuring the normal component of tension. In these zones, the normal component changes sign, indicating a change in the internal structure of the metal.
Special control devices make it possible to determine the relative values of the magnetic properties of controlled objects in a wide range of their changes.
Why is defect control so important?
Every year, several hundred man-made emergencies entail significant economic losses and even death of people. The main causes of accidents and failures at production facilities are the following reasons:
- Corrosion damage to metal structures;
- Lack of construction and installation works, factory defects of materials and equipment;
- Mechanical damage;
- Violation of the rules of operation technology.
Unsatisfactory technical condition of metal structures may occur due to:
- The presence of defects in the discontinuity of the material;
- Inconsistencies in the geometric parameters of the design normalized;
- Inconsistencies of physical and mechanical characteristics with the normative value.
It becomes clear that the issue of monitoring the materials of metal structures is currently quite relevant, since the performance of all industrial facilities, as well as the health of production workers, depends on it. That is why it is necessary to regularly monitor the functioning of the equipment, noticing any defects in a timely manner.