Abstract: A method for measuring the degree of fusion involves: a step for creating a dividing pulse amplitude curve by using a probe that emits ultrasound beams; a step for scanning the probe that emits ultrasound beams at a predetermined angle on a surface that has weld beads of multiple welding specimens having different degrees of fusion and for obtaining beam path length information from the dividing pulse amplitude curve and the height of an F echo that returned to the probe after hitting the fused section of a welding site; and a step for obtaining a regression formula expressing the relationship between the beam path length information and the degree of fusion.

Abstract: A method comprises a calibration curve creation step in which a calibration curve is created on the basis of hardened surface layer depth. A destructive test is performed on one of two samples in pairs, and propagation time of a first peak of a first wave of waveform of a signal outputted with the other in pairs in a non-destructive test is determined, the samples in pairs being prepared such that carburization depth varies gradually from pair to pair. A waveform of a signal outputted with a to-be-inspected piece is obtained. The propagation time of a first peak of a first wave of the waveform of the signal output with the to-be-inspected piece is obtained, and the hardened surface layer depth of the to-be-inspected piece is obtained using the calibration curve, on the basis of the propagation time obtained with the to-be-inspected sample.

Abstract: A method for measuring the degree of fusion involves: a step for creating a dividing pulse amplitude curve by using a probe that emits ultrasound beams; a step for scanning the probe that emits ultrasound beams at a predetermined angle on a surface that has weld beads of multiple welding specimens having different degrees of fusion and for obtaining beam path length information from the dividing pulse amplitude curve and the height of an F echo that returned to the probe after hitting the fused section of a welding site; and a step for obtaining a regression formula expressing the relationship between the beam path length information and the degree of fusion.

Abstract: A method comprises a calibration curve creation step in which a calibration curve is created on the basis of hardened surface layer depth. A destructive test is performed on one of two samples in pairs, and propagation time of a first peak of a first wave of waveform of a signal outputted with the other in pairs in a non-destructive test is determined, the samples in pairs being prepared such that carburization depth varies gradually from pair to pair. A waveform of a signal outputted with a to-be-inspected piece is obtained. The propagation time of a first peak of a first wave of the waveform of the signal output with the to-be-inspected piece is obtained, and the hardened surface layer depth of the to-be-inspected piece is obtained using the calibration curve, on the basis of the propagation time obtained with the to-be-inspected sample.