Cold Rolled Sheet 

Cold rolled sheet products have been available for many, many years, and have been successfully used for a multitude of applications. Today's cold rolled sheet products are much improved over those used in the past. They offer better control of thickness, shape, width, surface finish, and other special quality features that compliment the emerging need for highly engineered end use applications.

Cold rolled sheet products are used in a wide variety of end applications such as appliances - refrigerators, washers, dryers, and other small appliances, automobiles - exposed as well as unexposed parts, electric motors, and bathtubs. Cold rolled sheet products are used in these and many other areas of manufacturing. To meet the various end use requirements, cold-rolled sheet products are metallurgically designed to provide specific attributes such as high formability, deep drawability, high strength, high dent resistance, good magnetic properties, enamelability, and paintability. To assist the users of cold rolled sheet products, the steel producer needs to be aware of the many specific attributes required for the intended application. The following information is intended to provide users of cold rolled sheet products with information to assist them in selecting and ordering the proper product to meet their end application.

The first step in manufacturing U. S. Steel's Cold Rolled Sheet Products involves cold reducing coils of hot-rolled, pickled product to a thinner thickness. The cold reduction operation induces very high strains (work hardening) into the sheet; thus, the sheet not only becomes thinner, but also becomes much harder, less ductile, and very difficult to form. However, after the cold-reduced product is annealed (heated to high temperatures), it becomes very soft and formable. In fact, the combination of cold reduction and annealing lead to a refinement of the steel that provides very desirable and unique forming properties for subsequent use by the customer.

The primary feature of cold reduction is to reduce the thickness of hot-rolled coils into thinner thicknesses that are not generally attainable in the hot rolled state. Clearly, controlling the sheet thickness along the entire length of the coil is very important to ensure that the product will perform consistently during the processing by the end user. In addition, there are a number of other product attributes that need to be controlled in the cold reduction process. Flatness (deviation from a flat plane) is one of the more important attributes. Very sophisticated strip-shape controlling technology is used to maintain good flatness. Surface finish is another product attribute that needs to be controlled during the cold-reduction process. 

As one can see, there is much more to cold rolling than simply reducing the thickness to meet a customer’s ordered thickness. In fact, the hot-rolled, pickled coils incoming to the cold reduction mill have to have excellent quality attributes. The pickling operation must be well-controlled to assure that all the oxides formed during hot rolling are removed. The thickness of the hot-rolled strip is important in that the properties of the final cold rolled and annealed product is influenced by the percent cold reduction. This means that the thickness of each hot-rolled coil is carefully controlled to provide the mill with a specific thickness to achieve the proper percent cold reduction. Among other things, percent cold reduction affects the forming behavior of the product after annealing.

The production of a specific thickness of cold rolled sheet to meet an end user’s requirements involves very sophisticated processing from the melt stage forward. Steel chemistry, hot strip mill processing variables, pickling practices, cold-rolling mill practices, annealing practices, and finally, temper rolling practices all have a role in achieving the manufacture of top quality cold-rolled sheet products.

Production Methods The Cold Rolling Milll Additional Processing Temper Rolling

U. S. Steel produces the following cold rolled sheet products

	Cold Rolled Sheet Steel - This product is manufactured for a large number of applications that require a variety of properties from fairly simple to very sophisticated. The product is typically available at thickness as low as 0.0142 inch although lighter gauges may be ordered. Thicknesses lighter than this are generally ordered as Black Plate. Specific ordering practices allow the user to specify the following:
		Sheet dimensions
		Dimensional tolerances with respect to thickness, flatness, width, etc.
		Surface finish (Brushed Bright to Matte to Embossed)
		The metallurgical designation, i.e., Commercial Steel, Drawing Steel, Bake Hardenable Steel, Structural Steel, etc.
		Surface treatment, i.e., Special Cleanliness, Oiled, Dry lube, etc.
		Steel chemistry

	Cold Rolled Full Hard Sheet Steel - a product manufactured by U. S. Steel most often to be applied to further processing for applications such as continuous galvanizing. Specific ordering practices allow the customer to specify the following:
		Sheet dimensions
		Dimensional tolerances
		The metallurgical designation, i.e., Commercial Steel, Drawing Steel, etc.
		The steel chemistry

	Vitreous Enamel Sheet (Vitrenamel) - a cold rolled steel sheet product specifically processed with enhanced attributes for porcelain enameling. As with conventional cold rolled sheet. Vitrenamel Sheet can be ordered to specific dimensions and tolerances. There are three designations of Vitrenamel Sheet available from U. S. Steel:
		USS Vitrenamel 1Steel
		USS Vitrenamel 2 Steel
		USS Flexnamel Steel
	Each of these grades has special properties to allow their use for different types of porcelain enameling

	Cold Rolled Motor Lamination Sheet - specific grades of steel sheet made to be used for electro-magnetic core material for electrical equipment components. This includes motors, generators, and transformers. The primary property that is controlled during the manufacture of these steels is the core loss. Core loss is the energy loss in electrical equipment as heat generated by alternately magnetizing and demagnetizing the components. The magnitude of the core loss is determined by the chemical composition of the steel and the processing of the core material. The other important attribute is permeability which defines the ease of magnetization. U. S. Steel supplies the following products for use by the electrical-sheet industry:
		USS Type 1
		USS Type 2-S
		USS Q-Core
		USS Q-Core II
		USS Q-Core P 21
		USS Q-Core P 19
		USS Q-Core XL