PURPOSE: To distinguish a harmful defect from a harmless defect on a rod steel and a wire being a final product by means of supersonic defect inspection of square steel by comparing defect detection sensitivity from plural adjacent directions of the square steel to determine the kind of the defect.
CONSTITUTION: Twenty four probes 4a,4b,...4x are placed on four sides of square steel, and the opposite probes across the steel are placed so that their center axes are aligned with one another. Thus a cross section of the square steel is divided into thirty six blocks in grids based on the probe positions. By comparing defect detection signals by a defect inspection signal from the probes 4 placed on two adjacent sides per a quarter cross section comprising nine probes, defects detected on the same level from the two adjacent directions are determined to be harmful defect with non-metallic medium while defects which are detected only in one of the two adjacent directions are determined to be harmless internal cracks or internal gap defects. Thus quality estimation of the square steel can be securely performed, so that square steels with harmless defects can be prevented from being scrapped.
FUJISAWA JUNICHI
KAWATAKA HIROAKI
HAYASHI HIROAKI
| JPS61201155A | 1986-09-05 | |||
| JPS6455414A | 1989-03-02 | |||
| JPH01297551A | 1989-11-30 |