Steel Service Centers

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Service centers purchase various alloys of raw steel such as carbon steel, then process and treat them to fit the specific needs of their customers. The purchased raw steel undergoes different processes in service centers, and manufacturers may choose from hot rolled steel, cold rolled steel or aluminized steel, among others. These processes yield various types of steel to fit manufacturers' specific needs, which include high strength steel, spring steel, tool steel and many other varieties. A very long list of important steel products, including products like plate armor, shipbuilding materials, construction materials and many other examples, are processed in steel service centers. They offer a large inventory of steel in different pre-made shapes, including I beams and steel beams, steel plates, steel strip, and steel tubing. Galvanized steel products are also available from manufacturers and service centers. Because these steel service centers have a large inventory of steel at all times, ready to process and ship, the manufacturers save time and money because they do not have to worry about housing the steel themselves. 70% of steel purchased by steel service centers undergoes some type of pre-production processing. The steel is often aluminized, a cost-saving procedure where cold rolled carbon steel is hot-dipped in molten aluminum-silicon alloy that coats both sides of the sheet of metal. After this process, the steel has the lower cost and lighter weight of steel as well as the rust-resistant, conductive properties and smooth finish of aluminum. Aluminized steel takes on properties of both high strength aluminum and high strength steel. Steel may also go through a rolling process, which compresses and stretches the metal into an even grainflow through continuous rolling. Steel service centers will hot roll steel to obtain many different shapes, but hot rolled steel is generally characterized by lower structural integrity than cold rolled steel. During this process, steel is heated past its recrystallization temperature, which is around 1650°F, and it is pushed through rollers. The steel becomes very pliable and easily movable when heated, and as it cools its surface may oxidize, causing it to become less smooth and to take on a blue-grey finish. For steel that needs to be strong and have high structural integrity, steel service centers use cold rolling, which is done at or near room temperature. Because no heat is involved in this process, the risk of surface oxidization is eliminated. The shape range is very limited, though, because the steel is not heated anywhere near its melting point.

Service centers offer a variety of different types of steel to meet manufacturers' different needs. High strength steel (also sometimes known as High Strength Low Alloy, or HSLA, steel), which is optimal for transportation equipment because of its structural integrity, is often cold rolled or put through a post-cold rolled process such as quenching; quenching involves immersing the steel in cold water or oil in order to cool it. HSLA is alloyed with a number of metals, including copper, silicon, nickel chromium and phosphorus, for greater resistance to corrosion. Also, columbium, copper, vanadium and titanium can be added in small quantities for strengthening. More alloying elements typically increase material production and costs. Spring steel, a low-alloy, medium carbon steel with a high yield strength is hardened or tempered and often heat treated. Spring steel features silicon as an alloying component; the presence of silicon in the alloy gives the steel some flexibility. Spring steel is an adequate choice for manufacturers who need a strong, heat and abrasion resistant metal to make tools or the molds for plastic injection molding. It often contains additives such as cobalt and nickel to improve its performance under high temperatures, and its properties are increased through quenching in oil or air hardening.

Steel service centers have been in operation in the United States since the early colonial period. At that time, they were known as Iron Mongers, and only about 10% of all steel products in use at that time passed through service centers. Since then around 30% of industrial steel products and about 45% of specialty steel products are processed in steel service centers. Every steel product passing through a steel service center must be approved by the American Society for Testing and Materials, commonly referred to as ASTM, a non-profit organization dedicated to setting strict standards and ensuring the quality of products, materials systems and services, including all steel products, processes and materials. The ASTM's annually-updated book of standards covers steel pipes, tubes and fittings, steel plates, steel for machine structural use and steel for special purposes. More recently, the ASTM has developed new standards for annealed steel conductors. By combining the standards of annealed copper clad steel wire and hard drawn concentric-lay stranded copper clad steel conductors, ASTM will raise awareness about copper clad steel as an alternative to solid copper, increasing its production within steel service centers.

Images Provided by Block Steel Corp.

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Steel Types

• Alloy steel contains elements other than carbon such as chromium, manganese, et cetera. Alloy steels have a higher tensile strength, corrosion and oxidation resistance and ductility than carbon steel does.
  
• Aluminized steel is steel that has been hot dip-coated with an aluminum silicon alloy.
  
• Aluminum steel is a metal sheet that has been coated with an aluminum alloy.
  
• Carbon steel is a metal alloy composed primarily of iron with carbon being the second largest component imparting hardness and strength at varying degrees dependent upon the amount present.
  
• Cold rolled steel is steel that has been shaped without the application of heat. Cold steel has a smooth surface texture and is common in light-duty furniture and objects not needing the strength required of structural steel.
  
• Galvanized steel articles are coated with one or more layers of zinc in order to improve strength and corrosion resistance in industrial, commercial and domestic applications where steel parts are exposed to corrosive materials or are in high use.
• High strength steel commonly refers to all steel other than mild low-carbon steel. It is known for its structural integrity, high carbon and lighter weight.
• Hot rolled steel undergoes a process involving large pieces of steel that are heated above their recrystallization temperature and pushed between a set of rollers to form thin sheets, which exhibit heavy thickness, high strength levels and good formability.
  
• I beams are steel beams shaped like majuscule letter I's that are used in construction.
  
• Plate armor is steel that has been flat rolled, as opposed to steel in section form, and maintains a certain amount of thickness that is based on plate width. Plate steel is commonly used in construction and engineering.
  
• Spring steel is a low alloy, medium carbon steel with a high yield strength. It is made with silicone, and therefore has elastomeric properties-it can bend and stretch, then return to its normal state.
  
• Stainless steel, also referred to as "chromium steel," is the most common type of steel manufactured by steel service centers. This corrosion resistant material is preferred in the food and medical industries.
  
• Steel beams, used in the construction and engineering industries, are key players in the construction of large structures such as buildings and bridges because they are able to hold up great force and weight without bending.
  
• Steel pipes are round structures used in numerous applications to transport fluids and to provide structural support to bridges, buildings and stairs. Steel pipes maintain high strength and uniform thickness in rough industrial applications.
  
• Steel plates are flat rolled, made of stainless steel and manufactured in steel service centers.
• Steel strips are flat-rolled, very thin steel sheets used mostly in trim applications for the construction industry.
  
• Steel tubing and conduits provide support to railing, ladders, poles and exercise equipment and provide strong protection to conductors and wiring. Steel tubing varies in shape and wall thickness.
  
• Structural steel, also referred to as "plate steel," is low carbon steel containing manganese, which is commonly used in the engineering and construction industry for the production of buildings, bridges and transportation equipment. Structural steel has been hot rolled, often has a rough surface texture and includes steel beams.
  
• Tool steel consists of iron and alloys of chromium and other elements to improve steel properties, such as corrosion resistance. Tool steel is used in the production of hand and power tools.
  

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Steel Service Center Terms

Air Hardening - Also called "self-hardening," it is steel that is hardened through air cooling to reduce possible deformation.

Bloom - A semi-finished steel form with a rectangular cross-section that is more than 8". This large cast steel shape is broken down in the mill to produce the familiar I beams, H beams and sheet piling.

Carburizing - The application of carbon to a low-carbon steel surface to increase the strength of the steel. Carburizing is achieved through heating the steel in a substance containing carbon, followed by hardening the steel through heating and quenching the steel.

Casting - A method of steel formation in which a part is formed by the shaping of a molten material in a mold; it is commonly used for more specific parts. Casting is not used for the general production of steel types.

Composite - A solid material that consists of a combination of two or more constituents in which the individual components retain their separate identities.

Case - Surface of steel that has a different composition than the original makeup resulting from the application at elevated temperatures of carbon, nitrogen or another element.

Case Hardening - Steel treatment resulting in a steel surface hardness greater than that of the internal region of the steel.

Cold Working - Metal deformation process in which the metal is subjected to temperatures low enough to prevent re-crystallization of the metal during cooling.

Core - The internal region of a steel part that remains unaffected by case hardening.

Decarburization - The process whereby steel loses carbon from the steel surface layer due to contact with a chemical substance. Decarburization reduces steel hardness and strength.

Ductility - The ability of steel to accept deformation without fracturing. Ductility is a notable benefit of alloy steel.

Edge Rolling - The rolling of the edge of steel to smooth edges, which would be damaging or minimize functionality of a piece.

Hot Rolling - A steel production process in which steel is heated, pressed and shaped into the required form.

Normalizing - Steel heat treatment performed to refine grain size and to alleviate stress in the interior by heating the steel to temperatures ranging from approximately 800°C to 900°C (1472°-1652°F) and air cooling the steel.

Quenching - Rapidly cooling a metal from a high temperature.

Secondary Steel - Steel rejected by the first customer due to flaws, at which point the steel manufacturer or steel company must find another buyer.

Specialty Steel - A class of steels including stainless, tool, alloy and silicon electrical steels, as opposed to carbon steel.

Tensile Strength - The extent to which steel or another substance can accept bending or stretching without fracturing.

Yield Stress - The applied stress at which irreversible plastic deformation is first observed across the sample is called the yield stress, usually represented as sy.

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