The primary objective of this project is to test fatigue performance to characterize the effect of different chemistries and variable nickel content in zinc nickel (Zn-Ni) plating deposits on peened and unpeened 300M steel specimens. The resulting dataset will provide critical information regarding the suitability of Aerospace materials standard (AMS) 2461 Zn-Ni for use on aerospace fasteners.

Low hydrogen embrittling Zn-Ni (LHE Zn-Ni) has been tested and qualified for use as sacrificial coating to prevent corrosion to high strength steel alloys. LHE Zn-Ni is applied through electroplating process and is a drop-in replacement for cadmium. It offers superior corrosion protection compared to cadmium, while minimizing operational risks. LHE Zn-Ni has not been approved by the U.S. Air Force (USAF) and Navy for use on high strength aerospace fasteners. Most fasteners are electroplated per AMS2461 which allows a nickel range of 12-16% and various commercial plating chemistries. USAF and Naval Air Systems Command aerospace approvals are currently limited to LHE Zn-Ni per MIL-DTL-32648 which limits the plating chemistry to one Dipsol product and limits the nickel content to 12 – 15%, this severely limits the possibility of sourcing fasteners with Zn-Ni instead of cadmium. Fatigue testing and aerospace endorsement of AMS2461 plating chemistries will allow implementation of Zn-Ni on fasteners and strengthen the supply chain for all other components.

The expected benefits of this project include:

• Significantly reducing risks by eliminating cadmium. This translates to cost savings on exposure monitoring, medical expenses, and insurance while improving the well-being of depot maintenance personnel and field maintenance personnel.
• Better corrosion protection compared to cadmium; Navy gravelometry coupon test data showed five times corrosion performance improvement for Zn-Ni over cadmium.
• Potential for widespread adoption across the Department of War (DoW) for parts that currently require cadmium plating, pending confirmation of negligible fatigue impact of AMS2461 Zn-Ni. This expansion would diversify the supplier base leading to shorter lead times, increased competition, and lower costs.
• International specifications and standards committee leadership involvement in this project, if successful, is likely to result in inclusion of LHE Zn-Ni into these fastener and material specifications widely used in manufacturing, maintenance and repair requirements throughout the DoW as well as the worldwide aerospace industry as well as other industries such as oil and gas, nuclear and automotive industries etc.

(Anticipated Project Completion - 2029)