Differences between Hot Rolled Steel and Cold Rolled Steel

1.What is Hot Rolled Steel Material Grades
Steel is an iron alloy that contains a small amount of carbon. Steel products come in different grades based on the percentage of carbon they contain. The differing steel classes are categorized according to their respective carbon contents. Hot rolled steel grades are classified into the following carbon groups:
Low-carbon or mild steel contains 0.3 % or less carbon by volume.
Medium-carbon steel contains 0.3% to 0.6% carbon.
High-carbon steels contain more than 0.6% carbon.
Small amounts of other alloying materials such as chromium, manganese or tungsten are also added to produce many more steel grades. Differing steel grades provide several unique properties such as tensile strength, ductility, malleability, durability, and thermal and electrical conductivity.

2.Differences between Hot Rolled Steel and Cold Rolled Steel
Most steel products are manufactured in two primary ways: hot rolling or cold rolling. Hot rolled steel is mill process by which the steel is roll pressed at a high temperature. Generally, the temperature for hot rolled steel exceeds 1700°F. Cold rolled steel is a process by which steel is roll pressed at room temperature.
It is important to note that both hot rolled steel and cold rolled steel are not steel grades. They are the pre-fabrication techniques used for a variety of steel products.
Hot Rolled Steel Process
Hot rolled steel involves forming and rolling the steel slabs into a long strip while heated above its optimum rolling temperature. The red-hot slab is fed through a series of roll mills to form and stretch it into a thin strip. After forming is complete, the steel strip is water-cooled and wound into a coil. Different water-cooling rates develop other metallurgical properties in the steel.
Normalizing hot rolled steel at room temperature allows for increased strength and ductility.
Hot rolled steel is typically used for construction, railroad tracks, sheet metal, and other applications that do not require attractive finishes or precise shapes and tolerances.
Cold Rolled Steel Process
Cold rolled steel is heated and cooled just like hot rolled steel but is then further processed using annealing or temper rolling to develop higher tensile strength and yield strength. The additional labor and time for processing adds to the cost but allows for closer dimensional tolerances and provides a wide range of finishing options. This form of steel has a smoother finish and is used in applications requiring a specific surface condition and dimensional tolerance.
Common uses for cold rolled steel include structural parts, metal furniture, home appliances, auto parts and technical applications where precision or aesthetics is necessary.

3.Hot Rolled Steel Grades
Hot rolled steel is available in several grades to meet your project specifications. The American Society for Testing and Materials (ASTM) or the Society of Automotive Engineers (SAE) sets the standards and grades according to each metal’s physical structure and capabilities.
ASTM steel grades begin with the letter “A” which stands for ferrous metals. The SAE grading system (also known as the American Iron and Steel Institute or AISI system) uses a four-digit number for classification. Plain carbon steel grades in this system start with the digit 10, followed by two integers denoting the carbon concentration.
The following are common grades of hot rolled steel. Please note that some products are offered in both hot and cold rolled options.

A36 Hot Rolled Steel
Hot rolled A36 steel is one of the most popular hot rolled steels available (it also comes in a cold rolled version, which is much less common). This low carbon steel maintains less than a 0.3% carbon content by weight, 1.03% manganese, 0.28% silicon, 0.2% copper, 0.04% phosphorus, and 0.05% sulfur. Common A36 steel industrial applications include:
Truck frames
Agriculture equipment
Shelving
Walkways, ramps, and guard rails
Structural support
Trailers
General fabrication

1018 Hot Rolled Carbon Steel Bar
Next to A36, AISI/SAE 1018 is one of the most common steel grades. Typically, this grade is used in preference to A36 for bar or strip forms. 1018 steel materials come in both hot rolled and cold rolled versions, though the cold rolled is more commonly used. Both versions have better strength and hardness than A36 and are better suited for cold forming operations, such as bending or swaging. 1018 contains only 0.18% carbon and 0.6-0.9% manganese, which is less than A36. It also contains traces of phosphorous and sulfur but fewer impurities than A36.
Typical 1018 steel applications include:
Gears
Pinions
Ratchets
Oil tool slips
Pins
Chain pins
Liners
Studs
Anchor pins

1011 Hot Rolled Steel Sheet
1011 Hot rolled steel sheet and plate provide a rougher surface than cold rolled steel and plate. When galvanized, it is also used in applications where corrosion resistance is necessary. High strength and highly formable HR steel sheet and plate are easy to drill, form and weld. Hot rolled steel sheet and plate are available as standard hot rolled or hot rolled P&O.
Some of the benefits associated with 1011 hot rolled steel sheet and plate include increased malleability, high rate of production, and lower when compared to cold rolling. Applications include:
Building & construction
Automotive & transportation
Shipping containers
Roofing
Appliances
Heavy equipment

Hot Rolled ASTM A513 Steel
The ASTM A513 specification is for hot rolled carbon steel tubes. Hot rolled steel tubes are manufactured by passing heated sheet metal through rollers to achieve specific physical dimensions. The finished product has a rough surface finish with radiused corners and either a welded or seamless construction. Because of these factors, hot rolled steel tube is best suited for applications that do not require precise shapes or tight tolerances.
Hot rolled steel tube is easy to cut, weld, form, and machine. It is used in numerous industrial applications, including:
Engine mounts
Bushings
Building construction/architecture
Automobiles and related equipment (trailers, etc.)
Industrial equipment
Solar panel frames
Home appliances
Aircraft/aerospace
Agricultural equipment

Hot Rolled ASTM A786 Steel
Hot rolled ASTM A786 steel is hot-rolled with high strength. It is commonly manufactured for steel tread plates for the following applications:
Flooring
Treadway

1020/1025 Hot Rolled Steel
Ideal for construction and engineering applications, 1020/1025  steel is commonly used for the following applications:
Tools and dies
Machinery parts
Auto equipment
Industrial equipment

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