Methods of сorrosion testing used for development and commercial exploitation of new shipbuilding steels and alloys. Part I. Laboratory corrosion tests

Abstract

Shipbuilding steels and alloys may be subjected to various types of corrosion damage when exposed to sea water. For reliable long-term operation of ships and marine structures, despite the use of corrosion protection, materials are chosen that, in addition to the required mechanical properties, have sufficient corrosion resistance to ensure a given service life. Evaluation of corrosion resistance of new materials for use in shipbuilding was made by carrying out mandatory delivery trials using methods that have been repeatedly tested experimentally and whose results have been confirmed in practice. The complex study of corrosion resistance of steels and alloys is based on step-by-step laboratory, bench, and field tests. The review provides a brief description of laboratory corrosion test methods that are part of mandatory delivery trials. Parameters determining the aggressiveness of seawater as a corrosive medium, including salinity, oxygen content are considered. Laboratory test methods include electrochemical studies with determination of potential and rate of corrosion, pitting potential on the basis of polarization curves construction, as well as the generally accepted gravimetric method of corrosion rate determination. Installations for testing in moving (with varying flow rate) seawater are given.