Weldments in vessels and components for nuclear power generation must be of especially high quality due to the complexity and importance of this demanding service. Nickel-based products have been used from the outset of the nuclear age due to their corrosion resistance. From the 1950’s to the 1980’s the 15%Cr to 20%Cr welding products, Welding Electrode 182 and Filler Metal 82, were used until their susceptibility to primary water stress corrosion cracking (PWSCC) was discovered. This brought about the need for 30%Cr-containing alloys and welding products. Welding Electrode 152 and Filler Metal 52 (NiCrFe-7) were invented and used during the decades of the 1980’s and 1990’s. However, ductility dip cracking, DDC, was encountered during the early 1990’s, and a more resistant set of products (NiCrFe-7A) were introduced that had improved DDC resistance, improved weldability and met PWSCC requirements. These products were and are being used successfully for the mitigation of PWSCC-susceptible materials in existing nuclear plants and for fabrication of new plant and replacement equipment. Filler Metal 52M is currently being used for structural weld overlays (SWOL’s) and preemptive weld overlays (PWOL’s). As fabrication of new plant and equipment is needed, greater resistance to DDC is required. Therefore a new NiCrFe product, FM52MSS, was introduced that contains higher Nb and an addition of Mo (NiCrFe-13). This product provides over 4x higher DDC resistance than any of the currently available competitive products that have been tested. The Strain-to-Fracture (STF) test developed by the Ohio State University (OSU) has accurately measured the threshold strain to cause DDC in this product to be greater than 18% at 950°C. In addition, transvarestraint testing at OSU and PWSCC testing at the Pacific Northwest National Laboratory (PNNL) show excellent weldability and corrosion resistance. The product is registered as UNS N06055, AWS A5.14 ERNiCrFe-13, and has been assigned ASME Code Case 2142-3. This paper presents the outstanding attributes of ERNiCrFe-13.

Subject
Test methods, Materials, Nuclear power, Filler metals, Nickel based alloys, Welding, Stress cracking, Cracking resistance, Corrosion resistance, Grain boundary, Weld metal, Stress corrosion cracking, Ductility
Keywords:
52MSS, DDC, PWSCC, Corrosion, Nickel alloy
© 2012 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
2012
Association for Materials Protection and Performance (AMPP)
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