According to the principle of the ultrasonic pulse echo method used by JTUIS (Jiao Tong University Ultrasonic Imaging System),the cause that thin electric switch contact brazed quality cannot be well evaluated using the ultrasonic flaw echo testing method is researched.

By electrolyzing the sample taken at the defect determined by ultrasonic flaw detection on steel plate rolled from ingot,separating and reducing the inclusions in electrolyte,the size of the inclusions is found to be in the range between 100 to 500μm and in the shape of strip,polygon and sphericity.

There are many reasons for undetected defect such as unsuitable parameter selection of probe, the influence of interference wave and the unclear judgment of defect echo and burr echo.

The paper discusses the defect echo feature when applying different K value s probe detects different depth artificial reflectors in ultrasonic detection,and makes comparison among them,thus puts forward the significance of applying different K value probe on different detected parts,meanwhile it provides theoretical basis for practical detection work.

Image signal carried by ultrasonic echo is valuable information in diagnose.

Based on the principle of sand particle falling, a new method using the ultrasonic echo technique has been introduced for analysing particle sias.

Firstly, the basic principles of EMD decomposition method and neural network were introduced in this paper, ultrasonic echo signal was analyzed in time domain and frequency domain by EMD, and then the parameters of time and frequency domain characteristics were analyzed and summarized.