What is the Difference Between Hot and Cold Rolled Stainless Steel

The Difference Between Hot and Cold Rolled Stainless Steel

Cold Rolled: It is processed and rolled based on a hot-rolled stainless steel plate and coil. Generally speaking, it is a process of hot rolling→pickling→cold rolling. Although rolling will also heat the steel plate during the processing process, it is still called cold rolling. Because the hot rolling is cold rolled after continuous cold deformation, the mechanical properties are relatively poor and the hardness is too high. It must be annealed to restore its mechanical properties, and those without annealing are called rolled hard coils. Rolled hard coils are generally used to make products that do not need to be bent or stretched.

Stainless Steel Chemical Composition – YAOYI Stainless Steel

Cold Rolled’s Characteristics

1. The cold-rolled steel plate has a certain degree of work hardening, low toughness, and more expensive;


2. There is no oxide scale on the cold-rolled surface, and the quality is good;


3. Products made by cold deformation have high dimensional accuracy and good surface quality;


4. Because of its production process, cold rolling is widely used in various industries, such as various cold stamping parts, cold-rolled and cold extruded profiles, cold coil springs, cold drawn wires, cold heading bolts, etc.

AISI 304; AISI  301; AISI 316;AISI 316L…

 

Hot Rolled: It is relative to cold rolling. cold-rolled is rolling below the recrystallization temperature, while hot rolling is rolling above the recrystallization temperature.

Hot Rolled’s Characteristics

1. The toughness and surface smoothness is poor, and the price is low;


2. The temperature of hot rolling is similar to that of forging;


3. The hot plate is processed by hot rolling, and the surface has oxide skin, and the thickness of the plate is poor;


4. Due to its production process, it is used for civilian purposes, such as tableware, kitchen utensils, general household appliances, etc.;


5. The mechanical properties of hot-rolled steel plates are far inferior to cold working, and second to forging processing, but they have better toughness and ductility.

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What is the Cold Rolled?

Cold Rolled: Hot-rolled steel coils are used as raw materials. After pickling to remove the oxide scale, they are cold-rolled. The finished product is hard-rolled coils. Cold work hardening caused by continuous cold deformation increases the strength, hardness, and toughness of the hard-rolled coils. The plastic index drops, so the stamping performance will deteriorate, and it can only be used for simple deformed parts. Hard-rolled coils can be used as raw materials for hot-dip galvanizing plants because hot-dip galvanizing lines are equipped with annealing lines. The weight of the rolled hard coil is generally 6 to 13.5 tons, and the steel coil is continuously rolled on the hot-rolled pickled coil at room temperature. The inner diameter is 610mm.

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What is the Hot Rolled?

Cold Rolled uses slabs (mainly continuous casting slabs) as raw materials. After heating, the rough rolling mill and the finishing mill are used to make strip steel. The hot steel strip from the last rolling mill of the finishing rolling is cooled to a set temperature by laminar flow and then coiled into a steel coil by the coiler. The cooled steel coil undergoes different finishing operations according to the different needs of users. Lines (flattening, straightening, cross-cutting or slitting, inspection, weighing, packaging and marking, etc.) are processed into steel plates, flat coils, and slit steel strip products. To put it simply, a piece of steel billet is heated (that is, the hot steel block that is burning red on the TV) after a few passes, and then trimmed to be straightened into a steel plate. This is called hot rolling.

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The Difference Between Hot Rolled Plate and Cold Rolled Plate

1. The cold plate is processed by cold rolling, and the surface has no oxide skin and is of good quality. The hot plate is processed by hot rolling, and the surface has an oxide scale, and the thickness of the plate is lower.


2. The hot-rolled sheet has poor toughness and surface smoothness, and the price is low, while the cold-rolled sheet has good stretchability and toughness, but the price is more expensive.


3. Rolling is divided into cold rolling and hot rolling, with the recrystallization temperature as the distinguishing point.


4. Cold rolling: cold rolling is generally used to produce strips, and its rolling speed is relatively high. Hot rolling: the temperature of hot rolling is similar to that of forging


5. The surface of the non-plated hot-rolled board is dark brown, and the surface of the non-plated cold-rolled board is gray. After electroplating, it can be distinguished from the smoothness of the surface. The smoothness of cold-rolled boards is higher than that of the hot-rolled board.

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