Types of Steel: Materials, Shapes, Forms and Standards
Steel is a cornerstone material in construction, manufacturing, and various industries, known for its versatility and strength. Classified into carbon, alloy, stainless, tool, and specialty steels, each type serves distinct purposes, from building robust structures to resisting corrosion in harsh environments. Its forms — including bars, sheets, plates, and tubes — cater to specific applications, ensuring functionality across projects. Adherence to standards like ASTM A36 and ASTM A615 guarantees quality and reliability. Understanding these classifications and standards is essential for professionals navigating the world of steel, a critical component in engineering and design.
Common Types of Steel
Carbon Steel
Low Carbon Steel (Mild Steel): Contains up to 0.3% carbon. It's affordable, malleable, and used in construction, car bodies, and household appliances.
Medium Carbon Steel: Contains 0.3% to 0.6% carbon. It's stronger and harder than low carbon steel, used in gears, rails, and structural steel.
High Carbon Steel: Contains 0.6% to 1% carbon. Known for its hardness and strength, used in cutting tools, blades, and springs.
Alloy Steel
Contains additional elements such as manganese, chromium, nickel, and vanadium to improve specific qualities like strength, hardness, corrosion resistance, and toughness. Used in pipelines, auto parts, and electric motors.
Stainless Steel
Highly resistant to corrosion and staining, thanks to the addition of chromium (at least 10.5%). Used in kitchen utensils, appliances, medical equipment, and construction materials.
Tool Steel
Contains tungsten, molybdenum, cobalt, and vanadium in varying amounts to increase heat resistance and durability. Used for cutting and drilling tools.
Specialty Steels
Weathering Steel (Corten): Contains elements that lead to the formation of a protective rust layer. Used in outdoor sculptures and architectural structures.
Galvanized Steel: Coated with a thin layer of zinc to protect against corrosion. Used in roofing, car parts, and outdoor structures.
Common Shapes and Forms of Steel
Bar
Hot Rolled Steel Bar: This type of bar is made by rolling the steel at a high temperature, which makes it easier to shape. It's used for construction, frameworks, and manufacturing components due to its strength and flexibility.
Cold Rolled Steel Bar: Manufactured at or near room temperature, cold rolled steel bars have a smoother surface and tighter dimensional accuracy. They are used in applications requiring high precision, such as automotive parts and machinery.
Steel Reinforcing Bar (Rebar): Specifically designed to reinforce concrete, rebar is made from hot rolled steel and helps concrete withstand tension forces.
Sheet & Plate
Steel Sheet: Available in both hot and cold rolled versions, steel sheets are thin and flat. They are used in automotive bodies, appliances, and construction.
Steel Plate: Thicker than steel sheets, steel plates are used in heavy-duty applications like structural and construction work, heavy machinery, and bridge construction.
Steel Floor Plate: Known for its raised texture to prevent slipping, it's used for flooring, stair treads, and other surfaces where grip is important.
Steel Expanded Metal: Made by cutting and stretching metal sheets into a mesh, expanded metal is used for fencing, ventilation, and safety guards.
Structural
Steel Channel: U-shaped or C-shaped beams that provide structural support to buildings, bridges, and other structures.
Steel Beam: Typically I-shaped, steel beams are central to construction, providing support for buildings and large structures.
Steel Angle: L-shaped, steel angles are used in framing, supports, and cross-section reinforcement.
Steel Tee Bar: T-shaped, this steel is used for construction projects where a strong bearing capacity is needed.
Tube & Pipe
Steel Round Tube and Pipe: Circular hollow sections used in structural applications, transportation of fluids, and construction supports.
Steel Square and Rectangular Tube: These offer a higher strength-to-weight ratio and are used in structural, architectural, and industrial applications.
Common Steel Standards
ASTM A36
A36: A standard carbon structural steel specification that covers shapes, plates, and bars. It's known for its good weldability, machinability, and can be heat treated to harden its surface. Used in buildings, bridges, and other structural applications.
ASTM A615
A615: Specifies deformed and plain carbon-steel bars for concrete reinforcement. It's known for its strength and is used primarily in the construction industry to reinforce concrete.
ASTM A786
A786: Covers hot-rolled carbon, low-alloy, high-strength low-alloy, and alloy steel floor plates. Used for floors, stairs, ramps, and walkways where durability and slip resistance are required.
SAE 1055
1055: A high carbon steel known for its toughness and wear resistance, falling under the Society of Automotive Engineers (SAE) classification system. It's used for making cutting tools, blades, and other high-strength components.
ASTM Standards for Tubing and Pipes
ASTM A500: Covers cold-formed welded and seamless carbon steel structural tubing in rounds and shapes. Used in structural applications.
ASTM A53: Specifies seamless and welded black and hot-dipped galvanized steel pipe. Used for piping systems.
ASTM A992
A992: A standard specification for structural steel beams. This grade provides excellent strength and is commonly used in building framing and architectural support structures.
ASTM A1011
A1011: A standard specification for hot-rolled, carbon, structural, high-strength low-alloy, and high-strength low-alloy with improved formability steel sheets and strips. It's used in automotive components, appliances, and other industrial applications.