Customized Cold Rolled Stainless Steel Roll Aisi 409 202 304l 304 Stainless Steel Coil

Customised is four separate decisions

When a buyer asks for a customised cold rolled coil, the request usually contains four changes at once: a special width, a special thickness, a special coil weight, and a special finish. They are not equally easy, and the quantity you need is different for each.

Only one of them is a genuine mill decision. The other three are processing steps on a standard coil, which is why a supplier who treats them all the same will either overquote or fail to deliver.

What can be changed, and at what quantity

Width is slitting. A standard 1000, 1219 or 1500 mm coil is uncoiled, cut by rotary knives and rewound to any width from 20 mm upward. One coil is enough. Width tolerance is plus or minus 0.1 mm below 300 mm and 0.2 mm above, and the edge is a slit edge with a burr on one face.

Coil weight is cut and rewind. Any weight from 500 kg to 15 tonnes, at negligible cost, because the line is already running.

Finish above 2B is a pass. BA requires a bright annealing line, so the minimum is normally two to three tonnes. No.4 and HL are polishing passes, minimum one to two tonnes. PVC film is applied at any quantity.

Thickness is the mill decision. The gauge is set at the rolling mill and cannot be adjusted afterwards, so a non-standard thickness means a full heat at the steelworks: twenty to thirty tonnes and six to ten weeks. If your drawing calls for 0.85 mm and 0.8 mm will do, take 0.8 mm. It is a stock item and the price difference is large.

Specification

409 and 202 exist to save money, with conditions

409 is the automotive exhaust grade: 10.5 to 11.5 per cent chromium, stabilised with titanium, ferritic and magnetic. It is cheap because it contains almost no nickel, and it does its job well in a hot, dry, mildly oxidising exhaust stream. It is not an architectural or a wet service material. Put 409 where it will see road salt and condensation and it will show surface rust within months, which is the single most common disappointment with this grade.

202 is a 200 series austenitic with roughly 4 to 6 per cent nickel and 7.5 to 10 per cent manganese plus nitrogen. It forms better than 201 and is cheaper than 304. The limits are the same as 201: dry indoor use, no chloride, no continuous wet contact, and it is not a weldable pressure material.

Both grades are legitimate. Neither is a 304 substitute. If the drawing specifies 304 and the buyer substitutes 202 to save eight per cent, the saving is real and the corrosion risk has moved to the customer.

Coil ID is not a detail

508 mm is the dominant inner diameter in Asia; 610 mm is standard for many European and American lines. A coil with the wrong ID cannot be mounted on the mandrel, so it has to be rewound, which costs a day and puts a bend in the outer wraps. Confirm the ID before the coil is slit, because it is fixed at that point.

Finish and film

2B is cold rolled, annealed, pickled and skin passed: the default, grey and matte, suitable for forming and painting. BA is annealed in a controlled atmosphere so the surface stays bright without pickling; it is smoother and costs more. 2D is pickled without the skin pass and is duller, but it draws better because it retains lubricant.

PVC film is 50 to 70 micron, black, white or blue, and it protects a visible face during handling. Two rules: film left in sunlight bakes on and takes the surface with it when removed, and if the coil will be laser cut, specify a laser film, because a standard film releases chlorine in the cut and corrodes the edge.

Frequently asked questions

Can you slit to 150 mm from a 1219 mm coil?
Yes, seven strips of 150 mm plus edge trim, one coil minimum.

What is the minimum for a BA finish?
Two to three tonnes, because the bright annealing line has a minimum pass length.

Do you supply 409 with a 3.1 certificate?
Yes, with the heat number and the mechanical results.

Can the coil be supplied on a 610 mm ID?
Yes, on request, with a slightly longer lead time.