Abstract
Dissimilar Metal Welds (DMWs) made between ferritic low alloy steels and austenitic alloys are widely used in high temperature components of nuclear and fossil energy power plants. Literature shows that these bimetallic welds fail prematurely by creep mechanism close to the interface of the ferritic (BCC) and austenitic regions (FCC), with lifetimes much less than the creep lives of both materials. These creep failures are associated with cavity formation close to BCC/FCC interfaces. However, the spatial and temporal variations of creep strain rates in these DMWs have not been measured. In this research, DMW coupons were fabricated between 2.25Cr-1Mo steel and Alloy 800 H base material using a Ni base Inconel weld consumable. These samples were aged at 600 ℃ for 2000 h and 4000 h to induce two different sizes and distributions of Type I interfacial carbides and further subjected to a short term (~1 month) creep testing. Surface strains were measured with Digital Image Correlation (DIC) technique to extract local creep strain rates. In both samples, creep strain concentration occurred in the BCC matrix. The location of creep strain concentration from the BCC/FCC interface, changed from 5 µm (2000 h aged condition) to 400 µm (4000 h aged condition) depending on the initial carbide distributions in these regions.
| Original language | English |
|---|---|
| Pages (from-to) | 1-13 |
| Number of pages | 13 |
| Journal | Materials Science and Engineering: A |
| Volume | 749 |
| DOIs | |
| State | Published - Mar 11 2019 |
Funding
Authors like to acknowledge Christopher Stevens and Charles Hawkins for their help rendered in the set-up and operation of creep frame, and Tom Geer for his inputs on etching the samples for microstructural characterization. This work is funded by the U.S. Department of Energy Nuclear Energy University Program (DOE-NEUP); technical monitor: Dr. Richard Wright, Idaho National Laboratory ; under the agreement: DE-NE0008278 . This research was performed, in part, using instrumentation (Talos F200X) provided by the Department of Energy, Office of Nuclear Energy, Fuel Cycle R&D Program and the Nuclear Science User Facilities. Authors like to acknowledge Christopher Stevens and Charles Hawkins for their help rendered in the set-up and operation of creep frame, and Tom Geer for his inputs on etching the samples for microstructural characterization. This work is funded by the U.S. Department of Energy Nuclear Energy University Program (DOE-NEUP); technical monitor: Dr. Richard Wright, Idaho National Laboratory; under the agreement: DE-NE0008278. This research was performed, in part, using instrumentation (Talos F200X) provided by the Department of Energy, Office of Nuclear Energy, Fuel Cycle R&D Program and the Nuclear Science User Facilities.
Keywords
- Creep
- Digital Image Correlation (DIC)
- Dissimilar metal joining