| 摘要 |
PROBLEM TO BE SOLVED: To provide an ultrasonic flaw detecting method and apparatus capable of detecting the flaw of the blow hole microporosity of severalμm or less from perfect peel of a lapped part without generating irregularity in judgment and capable of also detecting the size of a molten part. SOLUTION: A point focus type probe 3 is driven at a certain position in a weld bead lateral direction by the bead direction moving mechanism of a two-axis scanner 7 and moved at a predetermined pitch in a weld bead direction to collect an A-scope image and integrates the A-scope images obtained during the advance over a predetermined moving distance to obtain the average A- scope image at a bead lateral direction position. Since the arrangement of crystal grains is wholly random, the phase of reflected waves interferes to lower the echos from the crystal grains. Contrarily, since a position where there is a flaw is uniform in depth in a weld bead direction, a strong echo wherein the positions of reflected echos are aligned on the A-scope returns to the probe to be emphasized by integration.
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