During automatic ultrasonic testing of electron beam welding（EBW）

phenomenon of the reflected wave in the upper and lower interface of thin layer aliases and interface echo and the flaw echo are difficult to identify because of thin thickness

the narrow weld and small defects of clutch driven disc.In order to improve resolution

sensitivity

and signal to noise ratio of ultrasonic testing system

effects of probe parameters on test results is discussed

and probe parameters are determined

and special probe which is used for ultrasonic testing of clutch driven disc is developed.The ultrasonic probe is frequency characteristic tested referred to European standards

and test results show that frequency property of special probe is superior to conventional probe and it is helpful to improve sensitivity and resolution and signal to noise ratio of the detecting system.The special probe can effectively distinguish slight defects of the equivalent size of approximate 0.4 mm when it is applied to the driven disc automated ultrasonic testing and can reaches detecting requirements.