Recent designs of commercial nuclear power plants, the so called 3rd generation plants, all make wide use alloy 690 (UNS N06690) for reactor and steam generator components. UNS N06690 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 UNS N06690 solved the PWSCC issue, there are still some issues involved with the corresponding switch in weld metals from N06082 to N06052. The N06052 is inherently more prone to hot cracking and ductility dip cracking, making welding much more challenging.

A new material UNS N06056 uses 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 N06052 commercially available. This new filler metal is now gaining interest in the nuclear materials community and is now being offered as a commercial product. The UNS N06056 weld wire is now covered by AWS and ASME codes and can be used as a filler metal and cladding weld metal for use in all commercial nuclear reactor components.

Subject
Materials, Nuclear power, Filler metals, Nickel based alloys, Welding, Stress cracking, Cracking resistance, Defects, Heat, Cracking, Cracks, Weld metal, Stress corrosion cracking
Keywords:
Nuclear, Welding, Weld Metal, Cracking, PWSCC, N06056
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2013
Association for Materials Protection and Performance (AMPP)
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