As a Material of Choice, Titanium Allows Submersible to Reach ‘Full-Ocean Depth’ By Michael C. Gabriele
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n business, when individuals or companies achieve major milestones or stellar accomplishments, they’re praised for having reached great heights of success. However, in contrast to this lofty description, Triton Submarines LLC, Sebastian, FL, has have been lauded for its great depth of success. How deep? Triton’s 36000/2 titanium submersible reached a depth of 35,853 feet or “full-ocean depth” (nearly seven miles) in the Pacific Ocean’s “Challenger Deep” region within the Mariana Trench near the island of Guam—the lowest-known point on the Earth’s ocean floor. By way of comparison, the peak of 14
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Mount Everest is the highest point on the Earth’s surface at 29,000 feet. Jarl Stromer, Triton’s manager of class and regulatory compliance, said his company designed, built and delivered the titanium submersible in 2019 to accommodate explorer Victor Vescovo and his “Five Deeps Expedition” to journey to the deepest points in the world’s oceans. Stromer explained that Pittsburgh-based Allegheny Technologies Inc. (ATI) served as Triton’s “most-important vendor” and strategic partner in the project. ATI produced a titanium Grade 5 ingot at its Specialty Materials facility in Monroe, NC, and then created the two interlocking hemispheres of the Triton 36000/2
submersible at its Forged Products plant in Cudahy, WI. Initially, Triton and ATI considered using nickel steels, Inconnel 718 nickel-based super alloy, aluminum alloys, and titanium Grade 23 to build the Triton sub, but eventually selected titanium Grade 5 (Ti 6Al-4V), the workhorse aerospace alloy. Grades 23 and 5 are similar, with Grade 23 offering higher ductility and fracture toughness. Stromer said ATI’s titanium Grade 5 prevailed because of its mostfavorable combination of properties, including strength-to-weight ratio and excellent corrosion resistance to seawater. Stromer said the decision was
