Steel plate

The reality is there are many nuances associated with steel plate and failure to understand them will result in many problems throughout its use in a project. The information in this eBook is meant to clear up many misconceptions.

Carbon steel plate is manufactured for a variety of applications based on its carbon content. Low carbon steel plate, depending on its thickness offers characteristics such as maximum cold forming capability, weldability and improved machining. Medium carbon steel plates (.40 – .50) that are silicon killed offers better strength capabilities but have limited machining and welding properties.

Other types of steel plate offer benefits for structure and construction applications, resistance to abrasion, and the ability to withstand high temperatures and pressures. Additionally, steel plate coils are available in low carbon, pickled and oiled, and black steel coils used for precision roller leveling. It may also be used for cutting standard and custom lengths up to 480”.

Steel plate standards

Structural steel shape properties, such as composition and strength are regulated by agreement between parties who choose to accept international standards. These international standards are created by formally recognized regulating boards, often times comprised of worldwide, volunteer members within respective industries.

It is customary for American made steel plate manufacturers to choose to have their hot rolled plates recognized by several of these governing bodies, such as ASTM International, ANSI, AISC, AISI, ASCE, ASME, and the AWS along with their European Union standards counterparts.

Iron and carbon are the most abundant materials present in steel. Pure iron is not particularly strong or hard on its own, so it is the addition of carbon that helps give steel its great strength.

The crude iron used to produce steel has a relatively high amount of carbon. Its carbon composition can be as high as 2.1%, which is the greatest amount of carbon a material can contain and still be considered steel.

However, iron can be processed further to reduce carbon. This manipulation of carbon alters several material properties, including:

Strength: The load a material can bear, measured by yield point and tensile strength. Yield point is the point at which a material deforms, but does not break, and tensile strength is the amount of stress needed to actually break a material.

Ductility: The amount a material can be stretched without becoming brittle. Ductility is measured by elongation, which is the percent the length of a material increases before it breaks.

Hardness: The wear resistance of material and machinability of material. This is usually measured on the Rockwell hardness scale or Brinell Hardness scale.

The carbon present in steel is typically reduced so that it fits into three main categories of carbon steel: low (or mild), medium and high carbon steel. Each of these categories contain different levels of carbon, show in the chart below.

Carbon steel plate almost include all the common standards of steel plate/sheet.

1. ASTM A36 plates – The most common standards of carbon steel plate
2. ASTM A283 Grade A, B, C – Also most common material in carbon structural.
3. ASTM A516 – For boiler, vessel steel plate.
4. ASTM A537 – For heat treated carbon steel plate in fusion welded pressure vessels and structural steel plates.
5. ASTM A573 – A kind of structural steel plate with carbon-manganese-silicon.
6. ASTM A572 – ASTM A572 plate mechanical strength is higher than A36. Where with lower weight.
7. ASTM A737 – For boiler, pressure vessels steel plate of low alloy steel. and etc..

So carbon steel plates have a widely coverage for different types of steel plates in different industries.

Also known as mild steel, low carbon steel has low strength relative to steel with higher carbon levels. Low carbon steel is the most ductile – or machinable – type of carbon steel as well.

Chemical alloys can also be added to low carbon steel to enhance desired properties without increasing the material’s weight. For example, if low carbon steel requires greater hardness for its desired application, manganese can be added to increase hardness without adding weight. Low carbon steel that contains additional alloys is typically referred to as high strength, low alloy (HSLA) steel.

Some of the most common low carbon steel plate grades, all stocked by us, include ASTM A36, A572 Grades 42 & 50 and A830-1020. Each of these grades have moderate strength, high ductility and lighter weight due to the low carbon content and addition of other alloys. These properties make low carbon steel ideal for use in structural applications like building construction, bridges and transmission towers, where materials must be able to withstand high stress while also being easy to form into structural shapes.

Medium carbon steel provides a balance between low and high carbon steel, offering greater strength and hardness than low carbon steel while still remaining more ductile than high carbon steel. Medium carbon steel also typically contains other alloys, such as manganese, that also contribute to its properties.

In applications where greater toughness and hardness are required, medium carbon steel plate can receive heat treatments – such as quenching and tempering – that enhance these properties without compromising its machinability.

Quenching and tempering is a two-step heat treatment process. In the quenching step of this process, steel is heated to a temperature between 1,500-and 1,650-degrees Fahrenheit, then rapidly cooled with water. In the tempering step, the steel is then re-heated to a below-critical temperature – between 300 and 700 degrees – and air-cooled. This process alters the crystal grain structure of steel to enhance hardness and other mechanical properties.

Two common medium carbon steel plate grades that stocks are ASTM A516 Grade 70 and A830-1045. The moderate carbon composition and additional alloys give these grades – and other medium carbon grades – a balance of strength, hardness, ductility and wear resistance. These properties make medium carbon steel ideal for use in applications where materials must withstand strong forces without breaking or wearing out, such as machine parts – including gears, axles and bolts – pressure vessel tanks and automotive parts and components.