The U.S. Navy is investigating whether the use of rust converter coatings used on steel surfaces to control unsightly rust during ship deployments results in environmentally assisted cracking (EAC) of the steel substrate material. In this study, the EAC resistance of HY-100 steel base metal and heat-affected zones (HAZ) was investigated using the slow strain rate test (SSRT) method, and high strength alloy steel socket-head cap screws were investigated using loaded test fixtures to simulate service conditions. Two different rust converters were evaluated using SSRT specimens, but only one rust converter was tested with the socket-head cap screws. Baselines and “worst case scenarios” were used for both tests. Test results from the SSRT testing suggest that rust converters do not negatively affect the EAC resistance of the HY-100 steel base metal and typical (55 kJ/in. [21.65 kJ/cm]) and high (110 kJ/in. [43.31 kJ/cm]) weld heat input HAZ material. Tensile results and fractographic analysis of the socket-head cap screws also indicate no evidence of EAC in the fasteners when rust converter is applied.

Subject
Scanning electron microscopy, Environmental cracking, Fixtures, Materials, Fracture surfaces, Screws, Intergranular cracking, Heat, Steel, Rust, Fasteners, Chemical conversion coatings, Slow strain rate technique
Keywords:
HY-100 steel, 4340 steel, steel fasteners, heat affected zone, rust converter coatings, environmentally assisted cracking, hydrogen embrittlement
Government work published by the Association for Materials Protection and Performance (AMPP) with permission of the author(s). Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
2005
GOV
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