Date of Award

6-2009

Document Type

Thesis

Degree Name

Master of Science in Material Science Engineering (MSMatSE)

Department

Materials Science

First Advisor

Dr. A l i Al Marzouki

Second Advisor

Dr. Yousef Haik

Abstract

In earlier works, characterization and stress corrosion cracking of casings of brine recirculation pumps used in desalination plants was investigated. These casings, which were manufactured from two types of Ni resist ductile irons, were reported to show different service lives. Material selection of casings is believed to be one of possible factors to extend the service lives of these pumps. Two types of stainless steels; UNS S31603 and UNS S32750 were recommended as substitutes to Ni resist ductile irons. In this work, mechanical, metallurgical, electrochemical and stress corrosion cracking (SCC) tests were conducted on as received samples, made from these two types of stainless steels. As stress corrosion cracking rig was constructed, calibrated and connected to an internet webcam for monitoring purposes. Results have shown considerable higher yield and tensile strengths and corrosion resistance for the UNS S32750 over the UNS S31603. Electrochemical tests confirmed this behavior and have shown reproduced pitting attack illustrated by measured pitting potentials and visual observations for the UNS S31603 samples. UNS S32750 samples have shown no signs of pitting. Furthermore, stress corrosion cracking tests in the hot brine environment have shown less resistance to stress corrosion for UNS S31603 samples as demonstrated by sample cracking failures after few days of stress corrosion testing. No stress corrosion cracking was observed for UNS S32750 samples under the same testing conditions.

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