SEATTLE — A metallurgist working in Tacoma was sentenced to 2 1/2 years in prison and a $50,000 fine after she spent decades faking the results of strength tests on steel that was being used to make U.S. Navy submarines.

Elaine Marie Thomas, 67, of Auburn, was the director of metallurgy at a foundry in Tacoma that supplied steel castings used by Navy contractors Electric Boat and Newport News Shipbuilding to make submarine hulls.

From 1985 through 2017, Thomas falsified the results of strength and toughness tests for about half the steel the foundry produced for the Navy. The tests were intended to show that the steel would not fail in a collision or in certain “wartime scenarios,” the Justice Department said.

Thomas pleaded guilty to fraud last November. U.S. District Judge Benjamin Settle sentenced her in Tacoma on Feb. 14, calling her actions a “crime of pride and ego, that in some way she knew better than those who set the standards,” according to a news release from Seattle U.S. Attorney Nick Brown.

The sentence was less than half the nearly six years sought by prosecutors.

“Our Sailors and Marines depend upon high quality products and services from our contractors to safely and effectively meet the worldwide mission of the Department of the Navy,” Navy Secretary Carlos Del Toro said. “We will continue to insist that our contractors must meet these high standards.”

There was no allegation that any submarine hulls failed. But authorities said the Navy has spent nearly $14 million, including 50,000 hours of engineering work, to assess the parts and risk to the 30 submarines affected. The Navy said it will incur further costs as it continues monitoring the subs.

Thomas’ conduct came to light in 2017, when a metallurgist being groomed to replace her noticed suspicious test results and alerted their company, Kansas City-based Bradken Inc., which acquired the foundry in 2008.

Bradken fired Thomas and initially disclosed its findings to the Navy, but the company then wrongfully suggested that the discrepancies were not the result of fraud. That hindered the Navy’s investigation into the scope of the problem as well as its efforts to remediate the risks to its sailors, prosecutors said.

In June 2020, the company agreed to pay $10.9 million in a deferred-prosecution agreement.

When confronted with the doctored results, Thomas told investigators, “Yeah, that looks bad,” the Justice Department said.

She suggested that in some cases she changed the tests to passing grades because she thought it was “stupid” that the Navy required the tests to be conducted at negative-100 degrees Fahrenheit.

In a letter to the court, Thomas said she was mortified at what she had done. Her attorney, John Carpenter, noted in a sentencing memorandum that she did not gain financially by faking the test results. He asked for a sentence of probation.