The corrosion resistance of types 347H and 310 stainless steels, 35Cr-45Ni steel, and chromized and aluminized type 347H SS were evaluated in simulated coal gasification atmospheres at 550, 600 and 650°C. Scales formed were mainly sulfides, with a small amount of oxides. Although the corrosion of 347H and 310 SS increased with increasing temperature, the corrosion of high chromium steels, 35Cr-45Ni steel and chromized 347H SS, remarkably decreased at 650°C. Weight gain decreased with increasing chromium content of steel. However, local corrosion occurred on 35Cr-45Ni steel at 600°C.

The aluminized samples were the most corrosion resistant of the materials tested, but some cracks were found in the aluminized layer after the 100 h exposure.

Addition of HCl to the simulated gasification atmosphere generally accel­erated the corrosion by formation of porous outer scale.

Pitting during downtime corrosion occurred only for 347H SS exposed in the simulated gas involving 0.2 vol% HCl. The results of electrochemical measurements suggested that the downtime corrosion might be polythionic acid corrosion and crevice corrosion in the solution involving Cl−.

Subject
Steel surfaces, Materials, Chromium, Weight gain, Corrosion scales, Oxide scales, Downtime, Scale formation, Steel, Coal, Corrosion resistance, Nickel, Chlorides
© 1986 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).
1986
Association for Materials Protection and Performance (AMPP)
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