In-Line Quality Control of Hot Wire Steel: Towards Innovative Contactless Solutions and Data Fusion (Incosteel)

The main goal of the Incosteel project has been to carry out research on new in-line hot steel wire inspection techniques. Surface defects must be detected in extreme operating conditions: up to 120 m/s rolling speed and temperatures from 850 °C to 1 200 °C (non-ferromagnetic behaviour above Curie temperature). Non-contact electromagnetic techniques have therefore been proposed and developed in the project. Conventional eddy current (EC) techniques show significant weaknesses to detect and characterise longitudinal and large surface defects in general. This is why EC arrays and electromagnetic acoustic transducers (EMATs), as well as a combination of techniques (data fusion) have been proposed. The EMAT technique was finally rejected because it was considered unfeasible for longitudinal defect detection, after performing several feasibility tests with experienced research centres, such as the SouthWest Research Institute (SwRI), CESI and Partykel Analytic (from RITEC). As a result, the project focussed on EC techniques in the end. The current encircling coil (currently in use in most rolling mills) was improved, and the concept of an EC array sensor was developed.