BRACKENRIDGE — Union workers at Allegheny Technologies plants in Pennsylvania and five other states were locked out starting Saturday.

The company announced the move Friday in a contract dispute.

About 1,100 United Steelworkers had continued working at plants in Harrison and Gilpin Township and Vandergrift in Western Pennsylvania after the last contract expired June 30. That extension also affected more than 1,000 other workers at plants in Connecticut, Massachusetts, Ohio, Oregon and New York.

The company has dropped a previous effort to eliminate the 8-hour workday and 40-hour workweek and other changes to overtime rules, but the union has continued to balk at having workers pay a share of their health insurance premiums.

ATI says it will keep the plants open with “salaried and non-union employees and temporary professional staffing.”