Micro-resolution Ultrasonic Imaging for Grade 92 GTAW Welds
Tracks
NDT Methods
| Wednesday, October 23, 2024 |
| 2:30 PM - 3:00 PM |
| 206 - Short Course & Technical Session |
Details
ASME Grade 92 (Fe–9Cr–2W–0.5Mo, wt.%) is a creep strength-enhanced ferritic steel designed to provide a better rupture performance in long-term high-temperature service environments than the former Grade 91 steel (9%Cr–1%Mo, wt.%). However, Grade 92 is still susceptible to Type IV cracking in the heat affected zone of the weld. The ability to effectively characterize weld zone microstructures in the field through imaging, with ultrasonic testing (UT) to monitor the microstructure degradation evolution in different regions of the weldment is an ideal nondestructive evaluation application.
In this investigation, weld zone microstructures of Grade 92 steel samples produced via single-pass gas tungsten arc welding (GTAW) with varying heat inputs were nondestructively analyzed using a patented micro-resolution ultrasonic imaging technique (MRUIT). The micro-resolution ultrasonic imaging system was configured in a through-transmission immersion setup to produce ultrasonic C-scan images. Additionally, electron-backscattered diffraction (EBSD) imaging analysis dislocation density, grain boundaries, and grain size was employed to understand the relationships between the effect of heat input and ultrasonic peak-to-peak amplitude distribution. The results indicated higher ultrasonic amplitudes uniformly distributed in the heat-affected zone (HAZ) compared to the base metal (BM) and weld metal (WM), which is likely due to HAZ's smaller grain size and increased dislocation density.
In this investigation, weld zone microstructures of Grade 92 steel samples produced via single-pass gas tungsten arc welding (GTAW) with varying heat inputs were nondestructively analyzed using a patented micro-resolution ultrasonic imaging technique (MRUIT). The micro-resolution ultrasonic imaging system was configured in a through-transmission immersion setup to produce ultrasonic C-scan images. Additionally, electron-backscattered diffraction (EBSD) imaging analysis dislocation density, grain boundaries, and grain size was employed to understand the relationships between the effect of heat input and ultrasonic peak-to-peak amplitude distribution. The results indicated higher ultrasonic amplitudes uniformly distributed in the heat-affected zone (HAZ) compared to the base metal (BM) and weld metal (WM), which is likely due to HAZ's smaller grain size and increased dislocation density.
Speaker
Obinna Onwuama
Ph.d. (graduate Research Associate)
The Ohio State Univ Dept of MSE (Welding Engineering)
Micro-resolution Ultrasonic Imaging for Grade 92 GTAW Welds
Presentation Description
ASME Grade 92 (Fe–9Cr–2W–0.5Mo, wt.%) is a creep strength-enhanced ferritic steel designed to provide a better rupture performance in long-term high-temperature service environments than the former Grade 91 steel (9%Cr–1%Mo, wt.%). However, Grade 92 is still susceptible to Type IV cracking in the heat affected zone of the weld. The ability to effectively characterize weld zone microstructures in the field through imaging, with ultrasonic testing (UT) to monitor the microstructure degradation evolution in different regions of the weldment is an ideal nondestructive evaluation application.
In this investigation, weld zone microstructures of Grade 92 steel samples produced via single-pass gas tungsten arc welding (GTAW) with varying heat inputs were nondestructively analyzed using a patented micro-resolution ultrasonic imaging technique (MRUIT). The micro-resolution ultrasonic imaging system was configured in a through-transmission immersion setup to produce ultrasonic C-scan images. Additionally, electron-backscattered diffraction (EBSD) imaging analysis dislocation density, grain boundaries, and grain size was employed to understand the relationships between the effect of heat input and ultrasonic peak-to-peak amplitude distribution. The results indicated higher ultrasonic amplitudes uniformly distributed in the heat-affected zone (HAZ) compared to the base metal (BM) and weld metal (WM), which is likely due to HAZ's smaller grain size and increased dislocation density.
In this investigation, weld zone microstructures of Grade 92 steel samples produced via single-pass gas tungsten arc welding (GTAW) with varying heat inputs were nondestructively analyzed using a patented micro-resolution ultrasonic imaging technique (MRUIT). The micro-resolution ultrasonic imaging system was configured in a through-transmission immersion setup to produce ultrasonic C-scan images. Additionally, electron-backscattered diffraction (EBSD) imaging analysis dislocation density, grain boundaries, and grain size was employed to understand the relationships between the effect of heat input and ultrasonic peak-to-peak amplitude distribution. The results indicated higher ultrasonic amplitudes uniformly distributed in the heat-affected zone (HAZ) compared to the base metal (BM) and weld metal (WM), which is likely due to HAZ's smaller grain size and increased dislocation density.
Biography
Obinna C. Onwuama is a Ph.D. student in Welding Engineering (WE) at Ohio State University with 13 years of mechanical integrity experience in the Oil and Gas Industry. He holds a BS in WE from The Ohio State University (2008), MS (2023), and an MBA from the University of Houston, Victoria (2013). As a Graduate Research Assistant, Obinna focuses on using advanced Non-Destructive Evaluation techniques and machine learning for microstructure characterization on high-quality field welding repairs for creep strength-enhanced ferritic (CSEF) steels. Obinna graduates in the summer semester (Aug) of 2024.
