The corrosion behaviour of nickel-base alloys and high alloyed stainless steels was investigated in the unwelded and welded state in a simulated chlorine dioxide bleached pulp washer environment. Laboratory tests were performed under electro-chemical control as well as in a solution with a defined ClO2-concentration at free corrosion potential. Nickel-base alloys in unwelded condition were prone to general thinning. Stainless steels with a very high resistance to pitting and crevice corrosion behaved quite sufficient.

Nickel base alloys welded either autogenously or with nickel base fillers showed general corrosion thinning in both base material and weld areas. Specimens of high nitrogen superaustenitic stainless steel 1.4565S (24 Cr, 18 Ni, 6 Mn, 4,5 Mo, 0.45 N) welded with iron rich fillers showed localized corrosion (pitting) in the weld area or no attack depending on the chemical composition of the filler, specimens welded with nickel base fillers showed a distinctive local corrosion in the weld area. This local attack could be contributed to differences in the dilution of the weld metal with the stainless base material leading to iron rich areas which are not attacked and nearly undiluted areas which are attacked.

Subject
Weld attack, Materials, Molybdenum, Stainless alloys, Nickel based alloys, Acidity, Corrosion attacks, Corrosion behavior, Steel, Pitting, Stainless steel, Nickel, Types of corrosion
Keywords:
superaustenitic stainless steels, nickel base alloys, filler metals, welding, chlorine dioxide, pulp bleaching environments, D-stage, transpassive corrosion, pitting, crevice corrosion
© 1991 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).
1991
Association for Materials Protection and Performance (AMPP)
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