HY-80
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HY-80 is a high-tensile, high yield strength, low alloy steel. It was developed for use in naval applications, specifically the development of pressure hulls for the US nuclear submarine program, and
Permit class USS Plunger on the building ways at Mare Island
USS Thresher (SSN-593)
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USS Thresher was the lead boat of her class of nuclear-powered attack submarines in the United States Navy. She was the U.S. Navy's second submarine to be named after the thresher shark.
HY-80
…steel were the Permit class. These reportedly had a normal operating depth of 1,300 feet, roughly two-thirds the crush depth limit imposed by the steel. USS Thresher, the lead boat of this class, was lost in an accident in 1963. At the time, this unexplained accident raised much controversy about its cause and the…
USS Thresher (SSN-593) under way, 30 April 1961
Launch of USS Thresher
Thresher at sea on 24 July 1961
Search operations underway near the accident site, 15 April 1963