Session: MF-06-02 Materials and Technologies for Nuclear Power Plants-2

Paper Number: 153637

153637 - Development of Modified Alloy 52 Filler Metal for Nuclear Class 1 Components 

Abstract: 

   Nickel based 52 filler metal is used for welding of dissimilar metals joints in nuclear power plant components, such as safe end weld of a reactor vessel nozzle, because of its high resistance to Primary Water Stress Corrosion Cracking (PWSCC). On the other hand, it is regarded that 52 filler metal tends to be inferior to conventional 82 filler metal in weldability. The typical concerns of 52 filler metal for weldability are susceptibility of hot cracking and amount of oxide film on weld bead surface.
   To improve the weldability, a modified 52 filler metal, which satisfies AWS 5.14 ERNiCrFe-7A, has been developed. To confirm the weldability, trans-varestrain tests, cladding tests, Gleeble tests, U-groove weld test and dissimilar joint weld tests were performed. The test results of the trans-varestrain tests revealed that Ta did not affect the hot cracking susceptibility while the total crack length remarkably increased with the increase of Nb content. Also, the hot cracking susceptibility decreased with decreasing of S and Zr. The cladding tests revealed that the oxide films of weld bead surface decreased with decreasing of Al and Ti. The modified 52 filler metal, which reduces S, Zr, Al, Ti and Nb and adds Ta, satisfies AWS 5.14 ERNiCrFe-7A. 
PWSCC constant load tests and crack growth tests were performed to compare the PWSCC resistance with the conventional 52 filler metal. Also, ultrasonic tests were performed to the weld joints using the modified 52 filler metal and the conventional 52 filler metal to confirm no significant difference between them. 
These test results are introduced.
 

Presenting Author: Seiji Asada Mitsubishi Heavy Industries, Ltd

Presenting Author Biography: - Graduated from Kobe University in March 1987
- Master’s degree from Kobe University in March 1989
- PhD from Kobe University in March 2009
- Joined Mitsubishi Heavy Industries in April 1989.
- Since joined in Mitsubishi heavy Industries, I have been in charge of designing and development of Reactor Pressure Vessels.
- Chair of SDO (Standard Development Organization) Convergence Board
- Member: [ASME Code Committee] BPV III, SG on Component Design, [JSME] Main Committee, SG on Design and Construction

Authors:

Seiji Asada Mitsubishi Heavy Industries, Ltd
Yusuke Sano Mitsubishi Heavy Industries, Ltd.
Kenji Kawasaki Mitsubishi Heavy Industries, Ltd
Naoki Suda Mitsubishi Heavy Industries, Ltd.
Masayuki Yasuda Mitsubishi Heavy Industries, Ltd.
Isao Seki Mitsubishi Heavy Industries, Ltd.
Takaharu Maeguchi Mitsubishi Heavy Industries, Ltd.