Suitable to be used as base materials for tin-plate, pre-painted steel coil, cold rolled steel coil product line, galvanized steel coil product line, and some simple metal parts.
Full hard cold rolled steel sheets are the finished products which use hot rolled steel sheets as base metal and shall be firstly processed through pickling line thus wiping off the oxide layers and then through cold rolling mill. The intensity and rigidity shall be increases while plasticity shall be decreased as a result of cold-induration coursed by continuous cold transmutation. because it has not been annealed, the hardness is very high(HRB shall be more than 85),hence its mechanical processing capability is so poor that it can only be applied to the simple bending processing in the direction of less than 90 degree(perpendicular to the direction of rolling.
Cold Rolled Full Hard Unprocessed Sheet is for direct use by customers for applications that do not require any formability beyond very limited bending and/or rollforming. It is supplied directly off the cold-reduction mill without any annealing to soften the steel. Thus, the steel is highly work-hardened, and exhibits a high resistance to denting, etc., but at the same time, it exhibits only minimal ductility. The hardness is Rockwell B 84 minimum.
Since the product is supplied directly after cold rolling without further processing, Full Hard Cold Rolled Unprocessed Sheet will have residual cold mill oils on the sheet surface. Also, the product, in coil form, includes off-gauge coil ends unless further processing is needed to facilitate processing through the customer’s operations.
Unprocessed Full Hard Cold Rolled Sheet is not subject to the same product standards that have been established for other cold rolled sheet products.
Cold Rolled Full Hard Sheet is produced to either nominal or minimum thickness. For nominal orders, the thickness tolerances are plus and minus around the ordered thickness. For minimum thickness orders, the thickness tolerance is all plus/nothing under the minimum specified.
Cold Rolled Full Hard Sheet product is provided with the surface finish produced on the cold reduction mill. This will be either a matte finish or a smooth ground finish depending on the product thickness and the mill processing parameters on the specific cold-reduction mill used to manufacture the product.
The standard practice is to provide Cold Rolled Full Hard Sheet product with the residual cold mill rolling oil on the surface. Any other customer requirement will entail special processing steps and added production cost.
Special processing can be applied to full hard sheet products. These include recoiling to remove off-gauge at the coil ends and tension leveling to improve shape. Also, a rust-inhibitive oil can be applied. However, this entails an additional processing step, i.e., temper rolling, recoiling, or tension leveling. If the product is ordered tension-leveled or cropped back to gauge, a rust-inhibitive oil can be applied at the same time. This product is ordered as Cold Rolled Full Hard Processed.
The full hard cold rolled steel sheet shall be used as base metal for Galvanizing line. Since the integrated galvanizing line shall be equipped with continuous annealing equipment, the thin full hard cold rolled sheet can be used as base metal to produce galvanizing products.
It also shall be applied to movable floor of control room and anti-static floor of advanced office, scientific research institutions and computer room, etc.
Movable floor of control room is usually formed by panel and baseplate after welding which is filled with cement in the aperture. The panel shall be recovered with other ornamental cover boards. Generally the baseplate shall use cold rolled steel sheet with deep drawing quality due to its more drawing points, and the panel shall use full hard cold rolled product with high flatness.
Supermarket shelves which are made of full hard cold rolled steel sheet should have a glossier surface without any injuries because its surface shall be chromium coated or treated by other methods later.
In umbrella-making industry, full hard cold rolled steel sheet is generally used in the production of umbrella handle and ribs. Since some of the umbrella ribs shall be electro-galvanized, the quality requirements including flatness, thickness tolerance and surface smoothness, etc.on these full hard products shall be comparatively higher.