Bonded joints and non-destructive testing: Problems in methods for the control of quality of butt welds made by the friction, cold pressure and flash welding processes

Abstract

Traditionally ndt of fusion welded joints for critical weldments is conducted during the final stages of fabrication on the basis of 100% inspection. The Author has long maintained (and it may be regarded by some as self-evident) that ndt serves industry better in circumstances where it can be used to monitor quality during production thus avoiding the production of expensive scrap.Unfortunately ndt methods, with few exceptions, cannot be considered particularly useful in either role when it comes to the control of quality of friction, pressure and flash welds. In this article an attempt is made to explain why this is so and why it is necessary to resort to sampling techniques and destructive tests to assess quality on the basis of circumstantial evidence. Recent trends have been towards the monitoring of process parameters in two of these processes and some measure of success has been achieved.