| About this Abstract |
| Meeting |
2023 AWS Professional Program
|
| Symposium
|
2023 AWS Professional Program
|
| Presentation Title |
Thermal Faceting on the Ductility-dip Cracking Fracture Surfaces of Nickel-based Alloys and Stainless Steel – Occurrence, Characterization, and Implications for the Cracking Mechanism |
| Author(s) |
Samuel Luther, Boian Alexandrov, Milan Heczko, Veronika Mazanova, Michael Mills |
| On-Site Speaker (Planned) |
Samuel Luther |
| Abstract Scope |
Ductility-dip cracking (DDC) fracture surfaces containing thermal faceting (TF) are extensively documented in this study. Research began with the unexpected discovery of TF on the DDC fracture surface in the weld metal of high-chromium nickel-based filler metal 52M, a valuable alloy to the nuclear industry. From there, TF was investigated and imaged again in many alloys, including nickel-based filler metal 52MSS, four variants of nickel-based alloy 690 containing multiple levels of sulfur content, and 310 stainless steel. Fracture surfaces were generated using strain-to-fracture (STF) and simulated strain ratcheting (SSR) on a Gleeble® thermomechanical simulator. TF was found to have several interesting characteristics, including directionality, changing morphologies in different alloys, and it appears to be suppressed by the presence of sulfur. Also, the temperature dependence of TF was narrowed to between 950 and 1150 °C in nickel-based alloys during STF tests. A few samples were selected for TEM characterization, where facets with preferred orientations and atomically sharp edges were observed. Several attempts were made to observe TF using liquid nitrogen fractures and focused ion beam (FIB) crack trenching. These methods successfully created DDC fracture surfaces, but TF was either not present or obscured by oxide layers. |
| Proceedings Inclusion? |
Undecided |