A New Improved Nickel-Based Weld Filler Metal for Use in Nuclear Power Plant Construction

A New Improved Nickel-Based Weld Filler Metal for

Use in Nuclear Power Plant Construction

 Recent designs of commercial nuclear power plants, the so called 3^rd generation plants, all make wide use alloy 690 (UNS N06690) for reactor and steam generator components.  Alloy 690 is orders of magnitude more resistant to primary water stress corrosion cracking (PWSCC) than the alloy 600 (UNS N06600) used in previous generations of nuclear power plant design.  While changing to alloy 690 solved the PWSCC issue, there are still some issues involved with the corresponding switch in weld metals from EN82 to EN52.  The EN52 is inherently more prone to hot cracking and ductility dip cracking, making welding much more challenging.

 Work done at Lockheed Martin 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 EN52 commercially available. This new filler metal composition is known as EN52i.  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 EN52i as a filler metal and cladding weld metal for use in all commercial nuclear reactor components.