A new austenitic corrosion resistant alloy of 28.5%Cr -40%Ni -1%Mo -0.15%N was developed for boiler tube application in waste incinerators. To combat corrosion due to chloride salts at low temperatures such as 400°C, Ni content was optimized to 40 wt.%. In contrast, the Cr content was set at 28.5 wt.% in order to assure a good resistance to sulfate/chloride salt mixtures at high temperatures such as 550°C. Localized corrosion such as intergranular corrosion and high temperature stress corrosion cracking (SCC) of conventional austenitic steels and alloys was studied by three point bent-beam test at 400°C with a chloride ash mixture in 0.15% HCl -300ppm SO2 -7.5% O2 -7.5% CO2 -20% H2O -bal.N2. High temperature SCC occurred for alloys of high Mo content whereas intergranular corrosion was obvious for low Mo and Mo free alloys. Nitrogen addition to alloys suppressed the intergranular corrosion drastically. Based on these findings, it was decided to add 1% Mo and 0.15% N to the new alloy.

Subject
New alloys, Intergranular stress corrosion cracking, Corrosion resistant alloys, Nickel based alloys, Molybdenum alloys, Mixtures, Commercial alloys, Steel, Ash, Grain boundary, Alloys, Intergranular corrosion, High temperature
Keywords:
hot corrosion, waste incinerator, chlorine corrosion, grain boundary attack, high temperature SCC
© 1994 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).
1994
Association for Materials Protection and Performance (AMPP)
You do not currently have access to this content.