Ultrasonic detection means to detect material and using ultrasonic and ultrasonic testing the work-piece, showing the way as a nondestructive testing method. Ultrasonic testing of many characteristics of ultrasonic is reflected and diffraction (as), through the observation shows in ultrasonic testing of ultrasound in relevant materials or workpiece was happened in the transmission, change is material and workpiece surface and the internal defects, and whether or not to damage the workpiece is material and assess the situation, the quality and use value. More than 20 kHz ultrasonic frequency is a wave (relative to the frequency range in 20 ~ 20 kHz speed of sound waves. Ultrasonic testing of ultrasonic, with its frequency range in general 0.25 MHz ~ 15 MHz. Used for metal materials, the ultrasonic testing of ultrasonic frequency range in 0.5 ~ 10 usually between MHz MHz, But for ordinary steel materials of ultrasonic wave, the frequency range usually 1 MHz ~ 5 MHz. With distinctive characteristics of ultrasonic, such as: acoustic beam directionality (energy concentration), Powerful sound pressure of high energy () transmission distance, Penetration ability, In the interface can produce reflection and transmission (or refraction wave transformation, and as the diffraction, etc. Usually, the ultrasonic inspection technology: According to the structure, can be divided into: continuous wave, pulse wave. According to different type wave, can be divided into: p-wave and shear wave plate surface wave, and creeping wave,, According to the different ways of receiving - can be divided into: echo (reflection), penetration, According to the different ways of coupling -- can be divided into: non-contact, liquid immersion type, According to the number of probe - can be divided into: single, dual probe and detector probe. Pulse echo (pulse reflecting) technology is used in the ultrasonic testing of a kind of technology, the use of ultrasound is a pulse wave, namely waves vibration short (usually microseconds only in order), in a short time amplitude (an intermittent launch) mechanical wave. Usually, pulse echo ultrasonic testing process by ultrasound detector is: (also called ultrasonic detectors) pulse signal input into the transducer, probe (or on), incentive transducer bimorph launch ultrasonic, Ultrasonic transmission (refraction) or be entered in the workpiece materials or after reflection or diffraction, eventually spread by transducer bimorph reception, again into electrical signal, ultrasonic testing to display, Finally, through the observation, the display to analysis and evaluation of the workpiece is material or internal or surface quality.
