Union members employed by Pittsburgh specialty steelmaker Allegheny Technologies Inc. have agreed to a four-year contract that ends a six-month lockout at 12 facilities in six states, including the plant in Midland. The United Steelworkers union announced last night that its members approved the deal by a 5-1 margin. The deal affects 2,200 workers. The National Labor Relations Board, which had filed an unfair labor practices complaint against ATI, must still approve the deal.