The calibration blocks are made from hot-rolled, corrosion- and heat-resistant high-temperature round steel bars diam. 100 mm, 40Х13 grade. The blocks represent a straight cylinder limited by two flat surfaces: operational and bearing ones. From the bearing surface side, there is a blind plain bore with a flat bottom (flat-bottomed reflector).
The calibration blocks allow to measure the following parameters of flaw detectors, operating in the frequency range from 1 to 10 MHz with straight-beam probes:
- deviation of conditional sensitivity by the effective reflector parameter by the occurrence depth from the nominal one;
- sensitivity margin;
- testing area range by distance;
- ‘dead zone’;
- sensitivity limit by the effective reflector parameter;
- depth-gauge error;
- conditional resolution by the occurrence depth and edge;
- frequency of flaw detector.
|Occurrence depth of flat-bottomed reflector, mm||1,0 – 180|
|Dynamic range of longitudinal ultrasonic waves (at frequency of 10 MHz), dB||1 ± 0,3|
|Velocity of propagation of longitudinal ultrasonic waves, m/s||6030 ± 30|
|Deviation of the amplitude of signal from flat-bottomed reflectors, dB||3|
|Spread of longitudinal waves, %||2|