(1) Principles of Magnetic Memory
The metal magnetic memory (MMM) - is a non-destructive testing methods, the basic principle is the leakage magnetic field distribution of the recording and analysis of self-produced parts and equipment in the stress concentration area. At this time, since the leakage magnetic field reflects the magnetization towards the irreversible change in the principal stress direction of the working load, as well as parts and welds in their manufacture and after cooling of the earth's magnetic field, the metallic structure and manufacturing process of hereditary. Metal magnetic memory method in the detection, the use of natural magnetization, and parts and equipment, metal deformation and metal organizational change manifested in the form of metal magnetic memory consequences.

(2) magnetic memory effect
The main source of damaged mechanical parts and metal components, micro and macro mechanical stress concentration. The most intense development in the areas of stress concentration, corrosion, fatigue and creep process. Mechanical stress with the self-magnetization of the ferromagnetic material and the residual magnetic conditions have a direct link, in the geomagnetic conditions, reduce the permeability of the defect at the workpiece surface leakage magnetic field increases, this characteristic of the ferromagnetic material said magneto-mechanical effect. Magneto-mechanical effect of the presence of ferromagnetic metal workpiece surface magnetic field strength the enhanced magnetic "memory" parts defect or stress concentration position, which is magnetic memory effect.

(3) detection principle
Is well known, the process cooling in the hardening process of the ferromagnetic member, the more intense cooling hardening may be formed becomes neck, neck variable at (Hp = 0 cross-sectional) will occur fast approaching dislocations formed in the member, and causing micro-cracks ─ ─ a later point of origin of the component damage or stress concentration line. When the stress concentration line forces and external loads perpendicular to the direction, the neck becomes initiator member faults must occur in the stress concentration line, if the stress concentration distribution along the axis of the member or stress concentration (HP value variation intensity)] is very small, the neck becomes The fracture of the location and the member often do not coincide; Nonetheless, as the load force increases, stress concentration to the neck becomes offset. Therefore, timely disclosure of existing metal member in the stress concentration line is very important.
Engineering components generated due to fatigue, creep and micro cracks cause the defect occurs at the stress concentration, experimental study shows that: ferromagnetic metal parts exist magneto-mechanical effect, the magnetic field distribution on its surface and components stress loads have a certain relationship, and therefore the magnetic field distribution of the surface by detecting member indirectly member defects and / or stress concentration for diagnosis.
The ferromagnetic member flaws or stress concentration region a magnetic field tangential component Hp (x) has a maximum value, the normal component Hp (y) changes sign and has a zero value. As shown in Figure 1. Practical applications, by the detection method to the component Hp (y)
To complete the detection of components.

The metal components of the stress concentration region is the root cause of the defect formation and development. Metal components are made of metal material processing, within the areas of stress concentration generated depends on the production process. Processing metal materials tend to be after melting, forging, heat treatment and processing, when the metal materials greatly exceeds the Curie point (768 ° C), wherein the residual magnetism disappears. But then the metallic material in the Earth's magnetic field gradually cooled (temperature lower than the Curie point), the crystals generated in the magneto-mechanical effect, but also formed a magnetic tissue. The microscopic structure of the metal member formed in the cooling process, including the metal constituting the particle shape and size, particle uniformity and configuration, the presence of inclusions or defects, etc., will be a metal form of magnetic memory manifested, constituting the member "genetic characteristics.

Under the existing conditions in the Earth's magnetic field, where the highest concentration of defects and inclusions in the metal member will appear fixed point of the magnetic domains and magnetic field leakage occurs at the surface. Centralized place in the defect concentrated local and internal stress, the magnetic permeability of the metal minimum, the maximum leakage magnetic field is formed in the surface. In the stress concentration area, the cutting of the magnetic field component of Hp (X) has a maximum value, while the normal component Hp (Y) changes sign and has a zero value. The size of the degree of stress concentration can judge according to the changes in the values ​​of Hp (X), the value and the direction of the magnetic domains of the member surface consistent. The closure domains direction is oriented along the axis of difficult magnetization and thus the anisotropy energy of the HP (X) value of the performance by the organization unevenness decision.

Metal member, the stress concentration line is not only closely related to the "genetic" characteristics of the member, and with the components in-service during the load and its direction of force and the large size relationship. Experiments show that member by the action of external forces during operation, due to the different of the direction and position of the external load force member stress concentration can be strengthened or weakened, if the concentration of stress lines and load of the member when the force directions are perpendicular to each other allows stress concentration line strength is lowered, damage will occur when the intensity is reduced to a certain limit member.

Theory and experiments show that the damage to the metal components and their innate "genetic characteristics and acquired Existing workload, the occurrence of defects, in the development process, the stress concentration is the root cause, is an early manifestation of component damage. Equipment accident is nipped in the bud, the importance of timely detection of the components of the stress concentration line. IDEAP0201 intelligent metal magnetic memory instrument new nondestructive testing system is developed from the above principle.

A member of the service equipment, since the relationship of its structure hereditary microstructure) (formed in the manufacturing and running in the load, the magnetic memory performance in a cumulative manner. The size of the force and direction of the operation member load will cause the metal magnetization on the magnitude and direction of the change. Magnetic memory diagnostic technology is developed according to the principle. The experiment proved that the effect of geomagnetism in the defects and inclusions parts of the existing ferromagnetic workpiece, will produce magnetic domain normalization phenomenon, and on which the leakage magnetic field. In relatively concentrated areas of the defect position and / or the internal stress, the minimum metal magnetic permeability, the magnetic field has a maximum tangential component, while the component changes sign and has a zero value. Leakage magnetic field component of the workpiece surface scan testing can determine areas of stress concentration, thereby indirectly determine the possibility of the ferromagnetic workpiece flawed. In order more intuitive to clarify the magnetic memory diagnostic techniques with traditional NDT detection technology (ultrasonic, eddy current, magnetic particle, penetrate, coloring, etc.) between component failure detection capability, shown in Figure 1 to illustrate this. Figure 2 shows the process of the development of the non-continuous change in the metal microstructure, wherein the abscissa represents the workpiece using the length of time, the ordinate indicates increase as the continuation of the time of defect levels. According to the detection principle of the MMM method, generally, assuming that the conventional detection method can be detected is greater than or equal to T0 at defects, MMM law can be detected is greater than or equal to T0 at the defects, and can found less than T0 defects. Therefore, MMM law is actually an implementation of metal failure of early diagnosis of non-destructive testing of new technologies.

Advantages:
1 the subjects object does not require any preparation (clean surface).
2, does not require artificial magnetization, because it utilizes the natural magnetization is formed in the workpiece during manufacture and use.
, Metal magnetic memory method can not only detect the equipment is running, also repaired equipment capable of detecting.
4, metal magnetic memory method - the only method to determine the equipment stress concentration area to 1mm accuracy.
5, in the prevention of losses from the damaged source.

Main applications:
1, machinery factories detect the workpiece metal and weld quality
2, all industrial sectors manufacture, repair and use of pipes, containers, equipment, any structure and workpieces (ferromagnetic material metal)
3, lifting and rotating machinery
4, in the laboratory study the mechanical properties of the metal