Recent designs of commercial nuclear power plants, the so called 3rd generation plants, all make wide use of UNS N06690 (commonly known as alloy 690) for reactor and steam generator components. UNS N06690 is orders of magnitude more resistant to primary water stress corrosion cracking (PWSCC) than the UNS N06600 (commonly known as alloy 600) used in previous generations of nuclear power plant design. While changing to UNS N06690 solved the PWSCC issue, there are still some issues involved with the corresponding switch in weld metals from ERNiCr-3 to ERNiCrFe-7. The ERNiCrFe-7 is somewhat more prone to fissures and cracking during welding, which can make the consistent production of sound welds more of a challenge.

Recent work has culminated in a special wire chemistry that balances the various requirements for resistance to hot cracking, ductility dip cracking, and PWSCC. This new filler metal has been tested in various joint designs and consistently out-performs all other variations of ERNiCrFe-7 commercially available. This new filler metal is now gaining interest in the nuclear materials community and is now being offered as a commercial product. While some additional application qualification testing will be required, the volume of test data already generated support the immediate consideration of ERNiCrFe- 15 as a filler metal and cladding weld metal for use in all commercial nuclear reactor components.

Subject
Materials, Nuclear power, Filler metals, Chromium, Welding, Wiring, Beads, Cracking resistance, Cracking, Grain boundary, Weld metal, Stress corrosion cracking, Ductility
Keywords:
Welding, weld wire, filler metal, nuclear, alloy 690, cracking, hot cracking, ductility dip cracking, primary water stress corrosion cracking
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2011
Association for Materials Protection and Performance (AMPP)
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