The "birth code" of stainless steel coils: from billets to coils, every step is a contest of precision

The production of stainless steel coils is a battle of "millimeter-level precision", and dozens of polishing processes are required from steel billets to finished coils. This article analyzes its core production process:

Smelting stage: accurately mix chromium (≥10.5%), nickel, molybdenum and other elements in the electric arc furnace. Taking 304 stainless steel coil as an example, the chromium-nickel ratio must be strictly controlled at 18:8. A deviation of more than 0.5% may affect the rust prevention performance;
Hot rolling into coils: After the steel billet is heated to 1200℃, it is rolled into a hot-rolled coil with a thickness of 3-12mm by a multi-roll rolling mill. The surface has oxide scale, which needs to be removed by pickling (the temperature of the pickling tank is controlled at 80℃±5℃ to ensure that the oxide scale is completely peeled off);
Cold rolling finishing: The hot-rolled coil is rolled multiple times by the cold rolling mill (the reduction rate reaches 70%), and finally forms a 0.3-3mm cold-rolled coil. The thickness tolerance can be controlled at ±0.01mm, just like the "metal rolling art";
Annealing and leveling: The coil after cold rolling is easy to be brittle due to internal stress, and needs to be heated to in a continuous annealing furnace. Keep the temperature at 1050℃, and then adjust the plate shape through the flattening machine (to ensure that the curvature per meter is ≤2mm) to meet the subsequent processing requirements.
A stainless steel factory once had a batch of 304 cold-rolled coils with insufficient toughness due to the annealing temperature being 50℃ lower, which caused cracks during stamping and resulted in direct losses of more than one million yuan - proving that "process parameters determine coil quality".