Reliability Engineering Snapshot TM

Illustrated Case Studies in the Maintenance Reliability Engineering World of Failure Analysis, Predictive Maintenance, and Non Destructive Evaluation




Material Properties - Case Study No. 3: RA253 Alloy Intergranular cracking


Stress Corrosion Cracking The RA253 material is special for high temperature service. The crack was located in a fired rotary kiln that operated at very high temperatures between 500 to 900 C. Cracks which appear to be shaped like the branches of a tree, or roots, signal a metallurgical change in the material that usually indicate that it can no longer serve its intended purpose.
There were several cracks such as the one above, and a couple were patch welded to keep product from leaking out (Figure 2). Within several months the repair started leaking again, and to no surprise, the new crack had the same branch-like appearance as the first crack.

The basic failure mechanism had occurred on an intergranular scale, the crack(s) actually following the grain boundaries of the material. If the problem were strictly structural, the crack would essentially be straight.

New Crack Starting From Weld Repair

All Pictures and Text Copyright © 1998 - 2016 Contact Mr. Adler Adler Engineering LLC of Wyoming USA

Great care has been taken in the compilation of this article. However, no warranty, expressed or implied, including without limitation, warranties of merchantability or fitness for a particular purpose, are given in connection with this article or any article archived on this website. Although this information is believed to be accurate by the author, the author cannot guarantee favorable results will be obtained from the use of this article alone. This article is intended for use by persons at their sole discretion and risk. Since the conditions of product or material use are outside of the author's control, the author assumes no liability or obligation in connection with any use of this information. The author is not liable for special, indirect or consequential damages resulting from the use of this material.

No part of this article or any article archived in this website, or any part thereof, may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, without the prior written permission of the copyright holder R. H. Adler. Nothing contained in this article or any article archived in this website shall be construed as a grant of any right of manufacture, sale, use, or reproduction, in connection with any method, process, apparatus, product, composition, or system, whether or not covered by letters of patent, copyright, or trademark, and nothing contained in this article or any article archived in this website, shall be construed as a defense against any alleged infringement of letters of patent, copyright, or trademark, or as a defense against any liability for such infringement.