Page 15: of Marine Technology Magazine (July 2023)

To help avoid poor Ti 6-4 material, end users must specify material sourced from “U.S. Mill or DFARS Only” in addi- tion to material assay certi? cation “Material Certs Required”. “DFARS” is the “Defense Federal Acquisition Regulation

Supplement”. The list of DFARS nations is rather lengthy. As a ? rst-order check, if the material assay certi? cation is in any language other than English, you may have a serious problem and need to double check.

Specifying Grade 2 unalloyed titanium provides a better shot at getting excellent corrosion resistance at the cost of strength.

I still call out “DFARS Only” in addition to requiring mate- rial assay certi? cations. There’s always the possibility that the wrong material is delivered with the certs from another run, but that requires diligence by and trust in your vendor. It helps if your vendor is ISO 9001 certi? ed.

The reader is referred to the SME text “Tool and Manufac- turing Engineering Handbook, Volume III, Materials, Finish-

Photo by Kevin Hardy, Global Ocean Design ing and Coating” for further discussion of Titanium metal-

Figure 2 lurgy and fabrication.

Corrosion of non-DFARS Titanium 6-4. The aluminum rich side corroded due to galvanic action.

GALVANIC SERIES AND ISOLATION

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