About 40 workers represented by the United Steelworkers Union at Allegheny Technologies Inc.'s Lockport plant are on strike.
The walkout began Tuesday at nine ATI facilities, including at 695 Ohio St. in Lockport. The Pittsburgh-based company makes specialty metals and components.
The union said it went on strike over unfair labor practices.
"In negotiations that started in early January 2021, the company sought major economic and contract language concessions from roughly 1,300 union members who have not had a wage increase since 2014," the Steelworkers said.
ATI said it was "disappointed" in the union's decision to strike.
"We remain dedicated to serving our customers and continuing to safely operate in the manner necessary to deliver our commitments through the use of our non-represented employees and temporary replacement workers," the company said.
In 2015 and 2016, ATI locked out Steelworkers-represented workers for six months before a new deal was approved.