Fig. 1.
The main magnetization, the magnetic hysteresis loop, and the related magnetic characteristics [11]
Fig. 2.
The hysteresis loop changes for steel subjected to cold working or caused by the non-magnetic addition: soft (1) and hardened (2) steels [11]
Fig. 3.
Magnetic measurement system schemes, based on a) permeameter; b) attachable transducer: 1 – the tested object; 2 – magnetizing coil; 3 – yoke of the magnetic circuit; 4 – winding on the tested object for magnetic flux measurement; 5 – magnetic flux density sensor; 6 – movable pole of magnetic circuit.
Fig. 4.
Magnetic Analyzer of type MA-05: a) general view of electronic unit with PC screen; b) an example of measurement results as hysteresis loop with calculated magnetic characteristics
Fig. 5.
The KRM-Ts coercive force meter with attachable U-shaped core magnetic transducer and two calibration specimens of known coercive force
Fig. 6.
Attachable magnetic transducers for KRM-Ts type coercive force meter
Fig. 7.
Spherical and cylindrical gas containers of aircraft selected for NDT inspection
Fig. 8.
The scheme of measurements and results obtained: a) measuring points diagram; b) resulting coercive force distribution along the container length
Table. 1:
Results of coercive force measurements
| Container | Material | HcB | Average Hc | Min Hc | Max Hc | Difference | Difference |
|---|---|---|---|---|---|---|---|
| type | A/cm | A/cm | A/cm | A/cm | A/cm | % | |
| 1 | 40HMA | 22 | 17.8 | 16.3 | 18.8 | 2.5 | 13 |
| 40HMA | 22 | 15.8 | 14.5 | 16.9 | 2.4 | 14 | |
| 40HMA | 22 | 15.7 | 14.3 | 16.5 | 2.2 | 13 | |
| 2 | 40HA | 20 | 14.6 | 14.2 | 15.3 | 1.1 | 7 |
| 40HA | 20 | 15.1 | 14.6 | 16 | 1.4 | 9 | |
| 40HA | 20 | 14.8 | 13.7 | 15.7 | 2 | 13 | |
| 3 | 40HA | 20 | 13.5 | 12.8 | 15 | 2.2 | 15 |
| 40HA | 20 | 14.7 | 13.8 | 15.7 | 1.9 | 12 | |
| 40HA | 20 | 14.2 | 13.5 | 14.8 | 1.3 | 9 | |
| 4 | 30HGSA | 24 | 18.5 | 18.1 | 18.9 | 0.8 | 4 |
| 30HGSA | 24 | 18.5 | 18 | 18.9 | 0.9 | 5 | |
| 30HGSA | 24 | 19.1 | 18.8 | 19.5 | 0.7 | 4 |