Stress Corrosion-Cracking and Corrosion Fatigue Impact of IZ-C17+ Zinc Nickel on 4340 Steel
Technical Report,01 Jan 2013,01 Jan 2015
NAWCAD Patuxent River United States
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Sacrificial metallic coatings like cadmium and aluminum are key protective materials for high-strength steels, corrosion-resistant steels and other cathodic materials used on aircraft. The effect of these coatings on the stress-corrosion cracking and corrosion fatigue performance of the base metals is critical to understand for intended applications. Although it works well, cadmium is toxic and a carcinogen and alternatives have been sought which are similarly effective but have minimal environmental, safety, and health risks. Aluminum is effective, but is expensive to apply. The currently used application method at Navy Fleet Readiness Centers FRCs, ion-vapor deposition IVD, is line-of-sight limited, meaning not all parts that can be electroplated with cadmium can be effectively coated with IVD aluminum. A new coating, a zinc-nickel alloy produced from a solution supplied by Dipsol, has shown promising performance for many coating requirements including general corrosion, adhesion, and flexibility. The stress-corrosion cracking and corrosion fatigue performance of this new coating was not known. In addition, the impact of corrosion-inhibiting primer and topcoat on these degradation mechanisms was not known. This report documents the work completed to assess the stress-corrosion cracking and corrosion fatigue of the IZ-C17 zinc-nickel coating with a trivalent chromium passivation Dipsol IZ-264 on 4340 steel, a common high-strength steel test substrate.
- Metallurgy and Metallography