Locked out U.S. Steel workers voted on a contract Wednesday that their employers is calling its final offer. But the union predicts it will be defeated.The deal on the table offers employees a $2,000 signing bonus, but charges higher co-payments on health plan benefits.It also cuts vacation for new employees and imposes a three year wage freeze. Workers rejected a previous version of the contract in April. The union has accused U.S. Steel of trying to buy votes from retiring workers.Since taking over Stelco in 2007, U.S. Steel has locked out its Canadian workers twice.(9:30pm Update)The workers have voted down the offer.