Title:
SURFACE-LAYER DEFECT FLAW-DETECTING METHOD
Document Type and Number:
Japanese Patent JP2531873
Kind Code:
B2
Abstract:
PURPOSE: To enable a position of an internal defect to be determined highly accurately by calculating the layer thickness of a surface-layer region, the distance from a side surface of a square steel piece to an inclined angle probe, and the time from the incidence of ultrasonic wave to its detection after reflection by the internal defect.
CONSTITUTION: An inclined angle probe S is placed on a side which crosses a surface 2 at a surface-layer region side of a steel piece 1. The evaluation distance Xw which is a distance to an internal defect F when the distance from the surface 2 to a probe S is a, the layer thickness of a surface-layer region is 2b, and the time from the incidence of ultrasonic wave of a propagation speed of C to its detection after reflection from the internal defect F within the surface-layer region is tF is obtained by {(C.tF/2)2-(a-b)2}1/2. By this method, as the evaluation distance Xw is reduced, an error range tends to be increased. However, the error &utri X stays within ±1.5mm and an error of Xw can be reduced by using 1/2 of the width 2b of the surface-layer region, thus enbaling the surface defect flaw-detecting accuracy to be improved.
Inventors:
YUYA KENJI
Application Number:
JP18868891A
Publication Date:
September 04, 1996
Filing Date:
July 29, 1991
Export Citation:
Assignee:
KOBE STEEL LTD
International Classes:
G01N29/04; G01N29/00; G01N29/22; G01N29/44; (IPC1-7): G01N29/04; G01N29/18; G01N29/22
Attorney, Agent or Firm:
Akeda Kan