Evaluation of braze welded joints using the ultrasonic method

Abstract

Brazed welded joints are increasingly used in the construction of motor vehicle bodies due to the fact that in the process of their manufacture, there is no damage to the zinc coating that protects the body sheet from corrosion. The main objective of the study was to evaluate the adhesion of the braze welded joint to the steel substrate based on measurements of the reflection coefficient |r| of the longitudinal ultrasonic wave. The tests were carried out using a 15 MHz longitudinal wave probe on three series of braze-welded joint samples. Each series was produced at a different setting of the inductance parameter, which allowed to modify the adhesion of the joint. On the basis of ultrasonic testing, it was found that the best adhesion that equals the lowest average value of the reflection coefficient |r| was 0.38. It was obtained by the samples made at the inductance parameter setting of 50%. In addition, all these samples had a small heat-affected zone, small plastic deformation as well as a small number of spalls were recorded. The proposed test technique can form the basis for fast and nondestructive inspection of braze welded joints used in vehicle bodies.

Keywords

• ultrasound
• adhesion
• braze welding joint
• ultrasonic wave
• car body