Abstract
The critical problem to accurately characterizing defects in GH3535 alloy weld is the deflection of the acoustic beam and scattering due to the coarse columnar grains. Signal-to-noise ratio is an important index to indicate whether the grain scattering is severe in the ultrasonic inspection. In this paper, the phased array ultrasonic testing of GH3535 alloy butt weld with the thickness of 46mm was studied using sector scan mode with linear array (LA) probe with 64 channels. The center frequency is 2.25MHz, and the incident angle is 19.87°. The sound field characteristics of the linear array probe with different focusing parameters were analyzed, and the signal-to-noise ratio (SNR) in the detection was calculated. The results show that: the grain size of butt weld ranges from 40um to 500um. The acoustic beam of the linear array probe can cover the weld thickness range of 5–39mm, based on the removal of weld reinforcement. The signal-to-noise ratio of transverse hole with φ3mm located at the weld-fusion line is more than 15dB, when the front end of the probe is located directly above the transverse hole of weld-fusion line.
