In the break room in the basic oxygen furnace building at Bethlehem Steel, crew leader Howard Wilmer, 60, an employee for 39 years, marks off his last days with the company this month. This is for a story about the rise and fall of Bethlehem Steel Corp. The company will change hands in late April/early May as part of a $1.5 billion sale to International Steel Group Inc. (ISG) Its steel mills, including the Sparrows Point complex in Baltimore County, will continue to operate.