| About this Abstract |
| Meeting |
2024 AWS Professional Program
|
| Symposium
|
2024 AWS Professional Program
|
| Presentation Title |
In Situ Digital Image Correlation Cross Weld Tensile Testing for Strain Concentration Characterization at the Fusion Boundary of Dissimilar Metal Welds |
| Author(s) |
William C. Siefert, Boian T Alexandrov |
| On-Site Speaker (Planned) |
William C. Siefert |
| Abstract Scope |
Dissimilar metal welds (DMWs) contain complex microstructures at the fusion boundary which are not present in the parent materials. These complex microstructures arise from the differences in material compositions and the metallurgical phenomena resulting from the welding process. These complex microstructures deserve attention due to their role in the in-service hydrogen assisted cracking (HAC) experienced in DMWs. It is hypothesized that these features act as stress concentrators, altering the local stress-state significantly which affects numerous aspects of the HAC failure mechanism.
Using Cross Weld Tensile Testing (CWTT) and Digital Image Correlation (DIC), the local strain state can be quantified, yielding valuable information on the stress-strain state in local regions. The fusion boundary (and its complex microstructures) exists in a small region. Using a micro sized sample, and micro tensile stage loaded in a Scanning Electron Microscope (SEM), the study of mechanical behavior at these reduced length scales becomes possible. Using in-situ DIC in the SEM, the local stress-strain behavior at the fusion boundary will be quantified under slow strain rate loading for typical microstructural features common in low alloy steel / nickel base filler metal DMWs.
Utilizing the CWTT in situ DIC experiment with a sample cathodically charged with hydrogen prior to slow strain tensile loading has yielded an interesting result: fusion boundary failure in an interface that is normally resistant to HAC when subjected to constant load testing under continuous charging with hydrogen. This failure will be subjected to further characterization to elucidate the difference in HAC mechanisms under slow strain rate in the presence of trapped hydrogen and under constant tensile load and presence of both diffusible and trapped hydrogen. |
| Proceedings Inclusion? |
Undecided |