MAGNETIC FLAW DETECTION METHOD EXCELLENT IN OBLIQUE FLAW DETECTING PERFORMANCE

PURPOSE:To improve an SN ratio by arranging a pair of detecting elements to perform differential detection at constant intervals in a zigzag shape on the bottom surface of a detecting element holder coming into contact with a steel material surface, and selecting a combination of elements according to an inclination of a flaw. CONSTITUTION:A combination of a pair of elements 1 to perform differential detection is selected from the detecting elements 1 arranged in a zigzag shape on an element holder 2 according to an inclination of a flaw. When a negative directional oblique flaw is detected, a combination of an An element and a Bn element is selected like an A1 element and a B1 element or an A2 element and a B2 element. When a positive directional oblique flaw is detected, a combination of an A(n-1) element and the Bn element is selected like the A1 element and a B2 element or the A2 element and a B3 element. Since this selection can be performed by internal operation processing, there is no need to increase new elements 1.