BATH, Maine — One day after Gov. Paul LePage signed into law a $45 million tax break for Bath Iron Works, leaders of the shipyard’s largest union blasted the management for laying off 31 employees while hiring for new positions. In a leaflet distributed Thursday at the shipyard, leaders of Local S6 of the Machinists Union wrote that the 31 layoffs announced Friday are in addition to 27 employees still out of work due to previous layoffs, whom Local S6 president Mike Keenan said Thursday have been denied new positions. On Friday, shipyard spokesman David Hench said the company expected that between attrition and new hires, BIW expects to hire and train approximately 500 people over the course of the year. Hench did not immediately return a request for comment on Thursday. The bill, signed Wednesday by Gov.