Significant interest exists in the use of super13Cr materials for oilfield applications. However, the hardness for both the weld deposit and the HAZ of different material combinations may exceed the NACE requirement of 23 HRC (253 HV). The objective of this program was to determine the influence of short post-weld heat treatment (PWHT) on the heat-affected zone (HAZ) mechanical properties and on the microstructure of three super-martensitic stainless pipe steels. The transformation temperatures, AC1 and martensite start formation, for each of the steels was determined by dilatometric analysis. HAZ weld simulations were performed with a peak temperature of approximately 1350°C and a cooling rate between 800 and 500°C of 40°C/s simulating normal GMAW heat inputs. A PWHT was performed in a Gleeble machine, at temperatures equal to Ac1, and 40°C above and below Ac1 for 5 and 10 min. The result showed that a short PWHT is effective in reducing the microhardness of the HAZ to levels very close to the hardness of the base metal in the as-received condition. It is assumed that the main mechanism responsible for the changes of hardness with PWHT in Pipe S steel is the amount of reverted and stable austenite.

Subject
Materials, Piping, Carbides, Microstructure, Microhardness, Base metals, Steel, Corrosion resistance, Ferrite, Hardness, Toughness, Austenite, Martensite
Keywords:
Supermartensitic, super 13Cr, Heat-affected zones, Post weld heat treatment, Mechanical properties, Microstructure, sour service
© 2004 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).
2004
Association for Materials Protection and Performance (AMPP)
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