Bloom

Bloom, in general, semi-finished rectangular or almost-square solid metal form, intermediate between an ingot and a billet in the hot-rolling process. A bloom generally has a cross-section of more than 225 square centimeters and is about 4.5 to 6 meter long. It is broken down in the rolling mill into finished products such as bars, beams, and sheet piling. In older steel mills blooms were produced from an ingot (and were called 'bloomery iron') but in modern mills they are made by continuous casting process.

Bloom production procedure:

Cast ingots, sometimes still hot, arrive at slabbing and blooming mills on railroad cars and are charged upright by a special crane into under-floor soaking pits. These are gas-fired rectangular chambers, about 5 meters deep, in which four to eight ingots are simultaneously heated to about 1,250° C (2,300° F). An ingot used for conversion into a slab can be 1.5 meters wide, 0.8 meter thick, and 2.5 meters high and can weigh 23 tons. The soaking pits are highly computerized for scheduling, firing rates, heating times (which can last 8 to 18 hours), and rolling programs.

After heating, a tillable transfer buggy brings a hot ingot to a two-high reversing mill, which takes one pass after another, reversing the rolls and roller table each time the ingot has passed through. Because each pass reduces the slab by only about 50 millimeters, it may take 21 passes, including several edge passes with the slab standing upright on its edges, to obtain a slab measuring 0.2-meter-thick, 1.5 meters wide, and 10 meters long.