Towards a calibration methodology for an in-series phased array ultrasonic inspection of weld cladding at elevated temperatures

In the early 21st century, rising manufacturing costs have incentivised industries to seek innovative solutions for producing high-integrity components more efficiently. One effective strategy is to perform quality inspections, such as Non-Destructive Testing (NDT), during production or in-process, rather than at the end of the process. This approach minimises rework, enhances schedule reliability, and boosts manufacturing throughput. Welding is a commonly used process in the fabrication of high-value and safety components, including nuclear pressure vessels, which are often clad with corrosion-resistant alloys. This cladding provides superior metallurgical properties on the surface while allowing the use of a more cost-effective base material, ultimately reducing overall production costs. Traditional code-compliant ultrasonic inspection methodology requires the calibration of the inspection parameters to known reference reflectors prior to and post inspection within a +/-14°C tolerance, preventing the accurate inspection of weld cladding methods during manufacture, when temperature variance can often exceed this range. Until now, in-process inspection has not been applied to weld cladding applications with a defined link to a calibration standard. This paper presents a novel approach to optimising ultrasonic in-process inspections by means of compensation strategies to mitigate the negative effects of elevated temperatures and their influence on material velocity and attenuation, manifesting as variation in reference reflector amplitude and sizing. The approach herein demonstrated the ability to effectively compensate for ultrasonic calibration parameters required for the inspection of an Inconel EN82H cladding over a steel substrate.