Abstract：The calibrating blocks of the incident points，refraction angles and scanning zeros of the concave surface oblique probe were the nondestructive testing technologies urgently needed for ultrasonic probes manufacturers，calibration laboratories and users. The technical characteristics and design principle of heel test block，as well as the special and conventional use of it were introduced.The heel test block could not only ensure the accurate location ofth edefects detected by the curved oblique probe，but also improvethe circumferential ultrasonic detection levelof convexsurface forgings，castings and pipes. At the same time，it could also be "one piece for many purposes" to test the performance and calibration sensitivity of the instrument.
2019, Vol. 37 
