The line focusing probes with focal lengths of 25mm

35mm

45mm and 50mm were selected

φ 1.5mm steel bar was used as reflector

by changing the relationship of position between the probe and the steel bar

the acoustic reflection characteristics of the line focusing probe in water were measured

and the detectable diameter range of the bar with different focal length was obtained; A line focusing probe with a focal length of 45mm was selected

φ 47 GH4169 superalloy bar sample was tested under different water distances

and the position of flat bottom hole used to determine the detection sensitivity of bar was obtained; φ 18 TC4 bar sample and the line focusing probes with focal lengths of 25mm

35mm

45mm and 50mm were selected

the experiments to characterize the reciprocating transmission of sound wave and directivity of sound beam were carried out

the selection method of water distance corresponding to the highest reflected wave amplitude of flat bottom hole used to determine the detection sensitivity of bar was obtained; The line focusing probes with focal lengths of 25mm

35mm

45mm and 50mm were selected

TC4 titanium alloy bar samples with different diameters were tested

the diameter range of detectable bar with line focusing probes of different focal length was verified. The measurement and characterization of acoustic reflection characteristics of line focusing probe and its application in bar inspection were solved.