This paper reports some factors of the influence on the manufacture of slab when the super-sonic fault detecting method is successfully applied. Some important factors are obtained by the authors by applying a comparatively simple but exact method. Also an interesting relation was found between the blister growing on the annealed aluminium plate and the fault detecting by the super-sonic method.
Some of the results obtained in this research are summarized as follows.
1) It is possible to indicate the degree of the fault by means of the total response and the frequency of the super-sonic fault locator and the number of pulses in the pulse transmission system.
2) Comparatively large faults, that is, crack, slag inclusion, blow holes and the like are detected in the echo obtained by the ordinary super-sonic method.
3) The super-sonic failure inspection by destroying the slab shows that the distribution of the pin holes well corresponds with the result of detection by the super-sonic method.
4) Utilizing the super-sonic method we can foretell the distribution of the larger blisters which actually appear on the rolled and annealed plate, while smaller blisters can not be located distinctly.
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