The Difference Between Cold-Finished and Hot-Rolled Steel

Business owners and makers have thousands of steel varieties on the market to choose from. With such an array of metal options, selecting the correct type, grade, and finish of your building material can be tedious. Pennsylvania Steel Co. offers a vast assortment of premium steel products at locations all over the United States. Plus, our online resources help our clients build the best projects possible.

Steel Manufacturing, Summarized

Not to be mistaken with the four main types of steel, the general steel manufacturing process falls into two main categories: hot-rolled and cold-rolled. This process starts with the extreme heating and consequent oxidation of mined steel ore.Basically, pieces of large, rectangular metal called billets are heated and flattened into sizable rolls. 

From there, the steel will go through one of the aforementioned rolling processes for its finalized design. “Rolling” refers to the vital step in the manufacturing process that involves forming the metal by using a series of rollers in an attempt to reshape it or enhance its properties. This formation method (hot or cold rolling) will determine the material’s ultimate function.

Hot Finishing Process vs. Cold Finishing Process

"In the conversation about hot-rolled vs. cold-finished products, all cold-finished products are hot-rolled, but hot-rolled products are not necessarily cold finished. Instead, it’s all a matter of how the bars are processed."

ryerson.com

Once steel is heated past its recrystallization temperature (over 1700º F) it can be easily formed and sized. If the material isn’t processed further at room temperature, it’s considered hot-rolled. The steel that goes through further refinement processes is categorized as cold-rolled. Explore further metal rolling methodology differences, capabilities, and tolerances below!

Hot-Rolled Steel

As hot-rolled steel cools, it tends to shrink and form asymmetrically, allowing for more variation in shape and size. For this reason, hot-rolled steel is used in projects where the finished product doesn’t have specific dimensional requirements.

For example, one of the most commonly recognized forms of hot-rolled steel is sheet metal, which is frequently used in creating air ducts and motor vehicles. In these applications, surface finish and proportions don’t need to be precise.

As a result, hot-rolled steel is typically cheaper in price simply because it doesn’t involve any further processing. Since it doesn’t require any reheating, production costs for hot-rolled steel are much lower.

Cold-Finished Steel

That being said, cold-rolled steel needs reheating to further refine its structural properties. In order to achieve more exact dimensions and surface quality, the metal is re-rolled at a lower temperature. This supplemental rolling results in more specified attributes including exterior finish, durability, and dimensional parameters. 

PA Steel, for example, carries a variety of cold-finished bars in a range of grades and finishes for businesses all over the eastern United States. This equipment is used for creating products such as furniture, garages, and home appliances.

Although it’s typically up to 20% more durable than hot-rolled, cold-finished steel is limited to basic square, round, and flat shapes. Despite its improved resistance, the additional processing performed on cold-rolled metals may make it more susceptible to internal stress. Finalized materials need to be stress relieved prior to grinding or cutting to avoid potentially volatile warping or distortion.

Determining the Appropriate Steel Type

Put simply, the last step in the manufacturing process will influence the final product’s application. If tolerance, surface finish, symmetry, straightness, or aesthetics are a key factor in the project’s creation, cold-rolled steel is likely the ideal choice. Conversely, hot-rolled steel can be used for large-scale or low-budget operations that can account for dimensional changes as it cools.

Tolerance Variety

The table below outlines the varying tolerances of hot-rolled vs. cold-finished steel products:

Data source: rapiddirect.com/blog/hot-rolled-vs-cold-rolled-steel

Premium Steel and Pipe Supply From Pennsylvania Steel, Co.

Visit our new and improved website to browse our selection of high-quality products, including several varieties of cold and hot-rolled steel, plus carbon tubing, stainless steel, finished bars, and more. PA Steel Company employs an expert team of industry professionals that are prepared to supply you with the ideal metal for any size project. Browse our locations in Pennsylvania, Richmond, Cleveland, Charlotte, Long Island, and more!

If you’re still having trouble figuring out the ideal steel production process for your project, check out our FAQ page or request a quote online today!

What are the Different Types of Steel?

Since steel is so versatile in its uses, reliable steel companies like Pennsylvania Steel offer various steel types for the multitude of projects our customers execute. The material’s type is determined by two main factors: the individual amounts of its alloy components (such as carbon and iron) and its production process.

The Four Main Types of Steel

Although there are technically over 3,500 types of steel available on the market with varying physical properties, we’re not going to provide you with a complete list of steel types. Instead, we will focus on four predominant types of steel: carbon steel, alloy steel, stainless steel, and tool steel. Learning the differences between these will help you understand which is the best for your project and why it’s the best for the job.

pa steel types of metal

Carbon Steel

As the name suggests, carbon steel contains mainly carbon and iron, and a trace of other elements (such as magnesium or chromium). There are three main subcategories of carbon steel which include:

  1. Low Carbon Steels (less than 0.3% carbon)
  2. Medium Carbon Steels (0.3% – 0.6% carbon)
  3. High Carbon Steels (greater than 0.6% carbon)

This specific profile will define the applications for your carbon steel type. While low carbon steels are very flexible and easy to work with, high carbon steels offer the most strength.

Generally, this type of steel is used in materials such as construction equipment and automotive components. In fact, carbon steel accounts for about 90% of total steel production in the entire industry because it’s inexpensive to produce and durable enough for use in large commercial projects. 

Alloy Steel

The name “alloy steel” suggests a large mix of different elements in addition to the characteristic carbon and iron combination. Examples of common additives are:

  • Magnesium
  • Chromium
  • Nickel
  • Silicon
  • Molybdenum
  • Titanium
  • Copper

The percentages of these elements will determine the appropriate application for the material. Manipulating these proportions changes the steel’s properties, such as heat resistance, hardness, and ductility. Companies often utilize this type of steel to produce commercial equipment like aerospace and aircraft components, transformers, pipelines, and power generators.

Stainless Steel

Steel in this category contains 10-20% chromium, making it incredibly resistant to corrosion and staining. This concentrated chromium coating also makes this material rust-proof. Classified by their microscopic structures, there are three subsets of stainless steel:

TYPE OF STAINLESS STEELGRADEPROPERTIES% ALLOYING ELEMENTSCOMMON USES
Austenitic300non-magnetic and non-heat-treatable18% chromium
8% nickel
<0.8% carbon
kitchen and food processing equipment
Ferritic400magnetic10.5-27% chromium
<0.1% carbon

heat exchangers and furnaces, auto parts
Martensitic400magnetic and heat-treatable
11-17% chromium
<0.4% nickel
<1.2% carbon
cutting tools, dental and surgical equipment

Stainless steel is a highly versatile material due to its notable resistance to heat and discoloration. Its unique resilience makes it the best type of steel for a number of industries, ranging from culinary and catering to standard machinery and cars.

Tool Steel

A combination of carbon and alloy steel, tool steel generally offers high hardness and abrasion resistance. These features, along with its superior ability to retain its shape, make it the ideal material for composing various tools. Surgical equipment, drills, dyes, bits, molds, and punches are examples of instruments made using tool steel.

Manufacturing quality tools requires quality steel components. PA Steel produces a number of different tool steels, which consist of carbon and alloy steels. Tool steel offers advanced abrasion resistance and toughness. We stock many different tool steel grades, including:

  • Air Hardening (A-Grades)
  • High-Carbon High-Chromium (D-Grades)
  • Shock Resisting (S-Grades)
  • Mold Quality/Hot Work (H-Grades
  • Oil Hardening (O-Grades
  • Water Hardening (W-Grades)

To learn more about our tool steel inventory, grades, and their applications, check out our detailed Tool Steel Guide.

Choosing The Best Steel For Your Project

As previously mentioned, the selected steel’s type identifies its key properties, including ductility, hardness, weldability, and more. Naturally, these qualities will determine the applied uses of the chosen metal.

In other words, selecting the wrong metal can prove detrimental to the quality of your project. For example, high alloy or low carbon steels are most effective in extremely cold temperatures because they retain high tensile strength even in frigid conditions. Therefore, residential and commercial structures being built in freezing climates should use these types of metals in their structural designs.

If you’re unsure about what your metal project requires, feel free to contact the specialists at Pennsylvania Steel for further insight into your ideal metal for the job. We can help you confirm your choice and walk you through your potential options for a high-quality result!

Contact PA Steel For a Custom Quote

Regardless of the job you take on, PA Steel offers a wide stock of the different types and grades of steel to help you prepare for your next project. Our knowledgeable staff has years of expertise, so feel free to contact the steel warehouse closest to you with any questions or to receive an estimate. We have steel supply warehouses in Pennsylvania, Virginia (Richmond), New York, New England, North Carolina (Charlotte), and Ohio.

Share This Post

Recent Posts