If ratified, the deal would bring an end to the company’s six-month lockout, which began in August. The National Labor Relations board also will need to approve the deal.

"This is a tremendous victory for a very brave group of workers. They should be proud of this agreement, and of the resolve they demonstrated throughout this six-month ordeal," said USW International President Leo W. Gerard in a statement.

"They showed us all the strength that we can have when we stand together in unflinching solidarity."

In a statement, Allegheny Technologies confirmed the tentative agreement, but said only that ratification was expected to take two to three weeks.

A company spokesman who was contacted by the Pittsburgh Post-Gazette newspaper declined further comment. The union said it won’t release contract details until after it is ratified.  

However, USW negotiator and vice president Tim Conway told the (Pittsburgh) Tribune-Review newspaper that he believed the agreement was a fair deal.

“I don't want to get into the details until the membership gets a chance to see it and the leaders get a chance to walk them through it. It's a good agreement, and I think our membership will agree,” he said.

The contract between the company and the union expired 30 June 2015. In August, the company locked out approximately 2,200 workers at 12 facilities after the union let lapse a company-imposed deadline to accept what it said was its last, best and final offer.

The union has said all along that the lockout was illegal. The National Labor Relations Board agreed, and earlier this month filed unfair labor practice charges against the company.

The company, however, denies those charges.