PREDICTION OF THE SERVICE LIFE OF NICKEL BASED ALLOYS N 06625 AND N 06059 AND SUPER AUSTENITIC STAINLESS STEEL S 31266 IN SEAWATER USING IN-HOUSE CREVICE CORROSION TESTS

摘要

The successful use of Ni-based alloys and highly-alloyed stainless in seawater applications depends on their ability to resist localized corrosion and in particular crevice corrosion. An extensive programme has been conducted by DCNS Cherbourg to optimise the use of such alloys for seawater pipings, identify their resistance to crevice corrosion and predict their performance under specific service conditions. This paper describes the in-house corrosion tests and methods used. The influence of several factors which are known to impact crevice corrosion initiation and propagation, such as crevice geometry, the nature of gaskets, temperature, the cleanliness of the surfaces and passivation treatments, are reviewed using these tests. The results of an evaluation campaign performed on Ni-based alloys A625 (UNS N06625), A59 (UNS N06059) and super-austenitic stainless steel B66 (UNS S31266) are presented.