Influence of Metallurgical Structure on the Service Performance of Ni-AI Bronze Process Equipment in Marine Environments

摘要

Nickel-Aluminum Bronzes often referred to as NAB are a group of Cu-based alloys containing about 3-6% Ni, 8-11% Al, 3-5% Fe and 1-3% Mn. These alloys have excellent physical properties such as fatigue, creep and wear as well as excellent resistance to different forms of corrosion such as general corrosion, cavitation, erosion and de-alloying. Hence, they find widespread use in marine environments as components of ships and industrial process equipment handling seawater. However, the corrosion resistance of these alloys can be adversely effected by their metallurgical structure which in turn depends upon the exact composition of the material and their manufacturing history - especially the thermal treatment to which they have been subjected. This paper will present two case studies of pre-mature failure of process equipment in seawater service which will illustrate the influence of metallurgical structure on the service performance of NAB in marine environments.