Thickness evaluation of thin laser cladding Fe314 alloy coating with surface ultrasonic wave based on wavelet analysis

The thickness of thin laser cladding coating is evaluated with surface ultrasonic wave based on denoising with wavelet analysis method. Two surface ultrasonic wave transducers with 5MHz frequency, which are employed as a transmitter and a receiver, are employed to detect surface ultrasonic wave signals, and cross correlation function is used to determine the difference in time between signals. Results show that the velocity of surface ultrasonic wave propagating in laser cladding Fe314 alloy coating decreases as the thickness of coating increasing, the microstructure of coating is the main reason for noise, the signal-to-noise ratio increases after denoising with db4 wavelet, the result of coating thickness and the difference in time is fitted with polynomial, and the fitting formulas are obtained responding to initial signal and denoising signal, respectively. Based on metallographic analysis result, this method is considered to be evaluated the thickness of thin laser cladding Fe314 alloy coating and the accuracy can be improved based on denoising with db4 wavelet.