Welding can have a profound effect on the structure, mechanical properties, and corrosion resistance of duplex stainless steels. After much effort has been given to controlling the structure of duplex stainless steels through restrictions of welding parameters, it is found that the chemical compositiion limits for UNS 31803 are too broad for such control. Increased levels of nitrogen improve the mechanical properties and corrosion resistance of weld metal and the HAZ through control of austenite reformation in welds. It is found that, for the typically produced levels of chromium, nickel, and molybdenum, UNS S31803 with a minimum of 0.15N will have an austenite level of about 55-60% in the base metal, and that welding with normal practices will not produce ferrite contents in excess of 65% in the weld metal or HAZ. Properties of GTAW, PAW, SAW, and SMAW were evaluated, all providing high ductility and toughness. The complex role of nitrogen in controlling corrosion resistance of the HAZ causes a problem of sample preparation substantially affecting results.

Subject
Piping, Metal surfaces, Ferrite content, Base metals, Gas tungsten arc welding, Nitrogen, Heat, Steel, Pitting, Corrosion resistance, Ferrite, Weld metal, Austenite
© 1987 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).
1987
Association for Materials Protection and Performance (AMPP)
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