The paper discusses the reasons and impact of variant wave and grain noise in ultrasonic testing of
TC4 titanium alloy plates with double crystal probe. The results show that quantitative evaluation of the defect pulse
wave amplitude is the most accurate by its beginning. The excessive pulse wave after the beginning of defects pulse
wave should be used to test with different focal lengths double crystal probe, and that the same orientation coarse al鄄
pha grains is the main reason for clutter signal generated. It is possible to decrease grain noise level by decreasing the
width of the pulse.