Improving the Accuracy of Hardness Measurement using UCI Transducers for Inspecting the Heat-Affected Zone of Welded Joints in Steel Pipelines
نویسندگان
1 Empress Catherine II Saint-Petersburg Mining University, Saint-Petersburg, Russia
2 Empress Catherine II Saint-Petersburg Mining University, Saint-Petersburg, Russia
3 ITMO University, Saint-Petersburg, Russia
4 Empress Catherine II Saint-Petersburg Mining University, Saint-Petersburg, Russia
5 Empress Catherine II Saint-Petersburg Mining University, Saint-Petersburg, Russia
6 Empress Catherine II Saint-Petersburg Mining University, Saint-Petersburg, Russia
doi
10.5829/ije.2026.39.10a.12چکیده
Quality control of welded joints involves hardness measurements of both the weld and the heat-affected zone (HAZ). However, standardized hardness testing methods require specimen preparation, leading to pipeline downtime. Among portable devices, hardness testers implementing the Ultrasonic Contact Impedance (UCI) method are the most widely used. However, measurement results depend on the calibration curve, which accounts for the elastic properties of the specimen and assumes their uniformity across the entire inspected surface. In the HAZ of a welded joint, changes in the metal's microstructure and elastic properties occur, leading to measurement errors in UCI hardness testing. This article presents a methodology for applying a correction to the calibration by accounting for actual changes in the elastic modulus within the HAZ, measured via ultrasonic wave velocity monitoring. As a result, hardness values incorporating this correction demonstrated better correlation with reference results obtained using a Vickers microhardness tester, indicating that the proposed correction improves the accuracy of UCI transducer measurements.
