The more steel is reduced in thickness by cold rolling, the harder it becomes. When steel reaches its "full hard" condition, it must be annealed to soften the coil for further processing. In the batch annealing process, an inner retort cover and a furnace are lowered over a stack of coils laid on their side. The gas-fired furnace heats through a controlled atmosphere of hydrogen or hydrogen / nitrogen to heat the coils. The heating, soaking and cooling process can take 3 to 5 days, depending on the grade of steel and desired metallurgical properties. Once coils are removed from the furnace, they are ready for further reduction rolling, temper rolling or finished as is, in their "dead soft" condition.
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Copyright © 2003 Blair Strip Steel Company.  Last updated December 6, 2006.
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