ULTRASONIC VELOCITY CHANGES IN X80 WELDED JOINTS WITH DIFFERENT MICROSTRUCTURES

Ultrasonic velocity is an important acoustic parameter inherent to every material and as such is a very important factor in material characterisation. The change in ultrasonic velocity can easily be put in correlation with different physical properties of a material such as hardness, grain direction, material inhomogenities, porosity, temperature, residual stress etc. In this paper 4 different welded joints were tested. Test specimens were welded with different metal transfer modes, heat inputs and shielding gases. Depending on the varied parameters different microstructure was obtained which proved to have influence on the ultrasonic velocity. Ultrasonic velocity on prepared samples was determined by using digital oscilloscope applying pulse overlap method.