"A provision of the Affordable Care Act, which is one reason Allegheny Technologies locked out more than 2,000 union workers last week at 12 plants in six states, also could be a stumbling block in negotiations involving two other major steel producers whose contracts covering about 30,000 union workers expire in less than two weeks.... Allegheny Technologies' final contract proposal was a four-year deal that included a provision requiring new negotiations during the life of the agreement if the company projected escalating premiums would trigger the tax."