A Research on Nondestructive Testing to the Metal Welding Residual Stresses by the Laser - Generated Ultrasonic

Abstract

Because the local weld of the metal is affected by high temperature in the welding process, every temperature is always uneven after the completion of welding. so in the cooling process, the temperatures of the different dots cause different contractions .This situation will lead to internal forces. These forces will eliminate external variant part outside, but the internal residues still exist. They are the welding residual stresses. This paper mainly introduces the principle of laser ultrasonic nondestructive testing technology and laser ultrasonic nondestructive testing technology about the application and research of the residual stress in metal welding.