Thickness Measurement of Alloy Steel Carburizing Layer Based on Laser Ultrasonic

Carburizing is one of the most widely used chemical heat treatment processes in the machinery manufacturing industry. The surface hardness, wear resistance and flexural fatigue strength of the workpiece after carburization is greatly improved. The thickness of the carburized layer is one of the main technical indicators to measure the quality of carburized parts. However, at present, the carburized shaft carburized layer thickness inspection is generally a contact method. In this paper, the thickness of the carburized layer of alloy steel was detected using Laser Ultrasonic (LU) non-destructive testing technology. First of all, using simulation signals to verify the effectiveness of sparse decomposition reconstruction and wavelet threshold denoising algorithm, and then the use of sparse decomposition and reconstruction combined with wavelet threshold denoising algorithm on the experimental LU signal denoising to extract the weak signal, obtained carburized layer thickness of alloy steel, accuracy of test results up to more than 95%. This study provides theoretical and data support for the development and application of on-line inspection equipment for carburized layers.