What is Metal Pickling and Oiling?

A spool of steel coil is an impressive sight: thousands of pounds of material, having been forced through immense pressure to form smooth, thin, gleaming metal. But this is the end product ready for sale, after the finishing process. Upon being freshly rolled, you may be surprised to find the steel’s appearance to be much more rough! This can be due to various causes from staining to rust, but most often the metal’s unpolished look will be due to mill scale. Mill scale, also referred to as scale, is a mixture of iron oxide residues which cling to the metal’s surface after rolling. It is typically a dark grayish color, with a rough and flaky texture.

Not only is scale unattractive-looking, it becomes a nuisance when left on the metal. Any coating applied over scale will be rough and uneven, and vulnerable to wear. Once water seeps under the scale, it will flake and fall off. So the effort to paint the metal is wasted; not only will the bare patch need repainting, but other scaly areas will eventually flake off and require repainting as well. For these reasons, scale is usually removed by the manufacturer before being sold.

One of the most common methods of scale removal for steel is pickling and oiling. This involves a lengthy multi-step procedure, but at its most basic, the metal is immersed in “pickle liquor” and oiled it as the final step. So what exactly happens during the pickling process?

  1. Loading: the material is carefully arranged on racks. Crowding the material, or allowing pieces to overlap, means the solution will not be able to reach all surfaces evenly.
  • Cleaning: the rack of steel is immersed in a highly alkaline cleaning solution, which will remove dirt and oil. While this step will clear the metal of surface debris, scale still remains on the metal.
  • Rinsing: the steel is carefully and thoroughly rinsed with water to remove the cleansing solution. This also helps to raise its pH level prior to the pickling.
  • Pickling: the rack is then lowered into a bath of hydrochloric acid, referred to as “pickle liquor”. The immersion in the potent acid effectively eats away at the bits of scale, as well as improving discoloration on the metal’s surface.
  • Second Rinsing: immediately after the pickling, the steel is rinsed to cleanse it of the acid.
  • Second Cleaning: the metal is again placed in an alkaline cleansing solution. This will neutralize any remaining acid residue from pickling.
  • Final Rinsing: the rack is removed from the cleaner and given one last thorough rinse.
  • Oiling: after pickling and rinsing, the metal will now have the smooth and shiny appearance we associate with steel. However, if we were to stop at this step, the steel would again be vulnerable to the accumulation of surface debris. The freshly cleaned surfaces are also now more fully exposed to air, which makes it more likely to rust. So the final step of the process is oiling, which protects the metal and provides a barrier to air and contamination. This involves placing the rack of steel in an oil bath to give it an overall coating. Whether using mineral oil or a water-based oil, the cover will help preserve the steel from developing flash rust while in storage. Once the metal is selected for additional fabrication, the oil will be removed via cleansing.

 As you can tell, the pickling process is lengthy and work-intensive. However, it’s also a necessary step to prevent oxidation and to prepare the metal for later processing. Without pickling, leveling a scale-covered coil to sheet would result in a product of subpar quality. And just as pickling a cucumber helps to preserve the vegetables’ shelf life, metal pickling and oiling does the same for the material. The manufacturer may not need to process their coil immediately, but it would be unfortunate to discover their stored stock has experienced “spoilage”: rust development and other damage. Properly pickled and oiled, the corrosion of your steel will be prevented for a much longer period of time.

What is a Ferrous Metal?

When classifying metals, focusing on a particular property is most often used as a way to divide them into two groups. Is this metal ductile or non-ductile? Is it magnetic or not?

When it comes to ferrous metals, one basic quality determines the groups: whether the metal contains iron. If iron makes up a large percentage of its composition, the metal is considered to be ferrous. If it contains no iron, or just trace amounts of it, it will be labeled a non-ferrous metal.

Beyond that, it becomes more difficult to apply general labels on the groups and the metals’ properties. While ferrous metals can range from iron itself to stainless steel, the alloying elements greatly affect the metal’s characteristics. For example, most ferrous metals are magnetic. But austenitic stainless steel is not, due to the high levels of nickel added to the steel for alloying. The nickel allows the steel to form in a crystal structure that is mostly austenite – and austenite is not magnetic.

So although it can be difficult to generalize about all ferrous metals as a group, there are some general characteristics that can be made about them. Ferrous metals are very hard and strong, especially in comparison to non-ferrous ones such as tin or copper. They’re vulnerable to rust due to their high percentage of iron, unless given corrosion resistance through alloying elements or protective coatings. And they’re usually (but not always) magnetic, which makes them very useful for motor and electrical applications.

The most common categories of ferrous metals include:

  • Carbon steel: there’s certainly no question of this being a ferrous metal, with over 90% of its composition being made up of iron. It is very hard and can keep a sharp edge, making it well-suited for mechanical uses such as drill bits and blades.
  • Cast iron: this metal is exceptionally hard due to its high levels of carbon, but the carbon also makes it quite brittle. For this reason, cast iron is now primarily used for smaller machine components or cookware.
  • Stainless steel: the most commonly used type of ferrous metals, especially for consumer goods. The addition of chromium is what makes a steel stainless, and gives it good corrosion resistance. And it’s magnetic, which is why you can stick magnetics on your refrigerator.
  • Alloy steel: the properties of this group of ferrous metals can vary much more widely than the others, since the alloy is specifically formulated for a particular purpose. So while alloy steels are ferrous, the added elements allows the metal to be tailored for more strength, ductility, hardness or other property.

Metal Aging through Precipitation Hardening

When it comes to metal aging, the simplest way to understand the process is in terms of heat. In general, if a metal has the ability to withstand high temperatures during heat treatment, then it can be aged. For alloys containing aluminum, copper, magnesium or nickel, aging is the principal method of strengthening the finished product.

When metal is exposed to heat, any impurities (precipitates) contained within it begin to form on the surface. These precipitates help to prevent dislocations, which are defects in the metal’s crystal structure. Because dislocations are a primary cause of metal weakness, this means the precipitates are acting as reinforcements to strengthen the metal. Aging it has made the material stronger, more stable, and more resistant. So it’s clear why accelerating these changes through artificial aging is a popular choice!

Precipitation Hardening

The basic process of precipitation hardening, or age-hardening, consists of three steps:

  1. Solution treatment: Also known as “solutionizing”, this involves heating a metal alloy to extremely high temperatures. This mix creates a solution, where the alloying material is suspended within the liquid base metal. More importantly, it dissolves the precipitates and helps disperse these particles evenly throughout the solution.
  • Quenching: Once an alloy solution has been created, the liquid metal is then cooled as quickly as possible. This quenching can be done using compressed air, oil, water, or brine. Whatever the method used, the aim is to “flash freeze” the metal so that the solid is as evenly-mixed as the solution. The faster it can be cooled, the less time the precipitates have to form on its surface.
  • Aging: The metal is heated again, although to a lower temperature to avoid any dissolving. Applying heat a second time ensures the precipitates within the metal are evenly dispersed. Afterwards the heated metal item is quenched a final time.

However, there are risks involved with heat treatment. Over-aging occurs when the metal is held too long at too high a temperature. This can result in uneven disbursement of precipitates in solution, which leads to cracking and distortion in the cooled product. When monitored carefully throughout the age-hardening process, metal alloys that have completed these steps will be a harder, stronger material.

The Aluminum Extrusion Process

What is extrusion?

Extrusion is the process of shaping material during manufacture. Generally, this is done by forcing a block of metal, called a billet, through a shaped die. Think of it like a frosting tip: whatever is squeezed out appears with the specific design you selected.

How is aluminum extruded?

For aluminum, the two main methods of extrusion are direct and indirect.

Direct extrusion is the most commonly used method, using a stationary die. The billet is heated to 800 – 925 degrees F, then laid on a loader and pushed through the die using a hydraulic press. The steady pressure squeezes the softened metal through the die opening. Using direct extrusion, this process produces a wide variety of solid bars, rods, and hollow tubing.

With indirect extrusion, the process is reversed – the billet remains stationary while the die is forced onto the metal itself. This creates far less friction on the billet than using direct extrusion. The result is a product with more consistent dimensions, grain structure, and mechanical properties. However, the method also has its disadvantages, mainly related to the lack of friction. Billets must be carefully cleaned, since little to no friction means any substances on the metal will affect the extrusion’s surface.

Why use the extrusion process?

Extrusion is favored for many metals since it is easier to manufacture, with aluminum being particularly suited for the process:

  • Quick fabrication and assembly: compared to other tooling processes such as stamping, casting or injection molding, extrusion has a shorter lead time and done at a lower cost. This means items will be much more quick-to-market, from prototype development to product launch.
  • Easy tailoring: there are already a number of standard aluminum extrusion designs already available. This speeds production and assembly, by improving performance and cutting down on secondary operations.
  • Strength: with the extrusion process, the metal’s strength can be concentrated in specific areas by varying the wall thickness and internal reinforcement of the design. This is even more of an advantage with aluminum extrusions intended for use in cold environments. Unlike other metals which can become brittle with cold, aluminum strengthens with lower temperatures. The combination of the extra reinforcement through extrusion, coupled with the property of the aluminum itself, makes for a dependably strong metal.
  • Excellent thermal and electrical conductors: aluminum is nearly twice as conductive as copper, and much less expensive a material. It also conducts both heat and cold better than many other common metals. Because of this, extruded aluminum products are an attractive choice for home builders. Its lower price, heat dissipation properties, and resistance to fire are all advantages for house framing.
  • Sustainability: aluminum can be recycled infinite times, with no degradation of the metal’s properties. This means extruded aluminum products often contain a high percentage of recycled content. The addition of recycled material to the primary aluminum has no effect on the finished product’s overall aesthetics or functionality.

What is Metal Aging?

Aging [verb]: the process of growing older. While that definition does apply, in the metals industry “aging” is specific jargon referring to treatments which speed up that process. But why would you choose to age your new metal products? It helps if you remember not to view aging as a negative. In fact, much like wine, the properties of a metal alloy often improve with age.

As metal ages, its base material physically transforms. The interaction of the metal’s atoms with the oxygen in its environment – whether surrounded by air or water – will begin change its surface texture and color. This starts with a basic oxide layer being formed. The oxide then becomes a hydroxide, and the hydroxide layer continues to interact with the atmosphere.

So why is this exposure to the elements considered a desirable result, unlike rust? That’s because iron oxide, or rust, is much more fragile and ultimately destructive when compared to a hydroxide. Exposed iron develops rust which flakes off and forms again, and will continue this cycle until it deteriorates the metal below. Meanwhile, a hydroxide layer actually creates a more stable surface composition. This hydroxide effectively creates an outer shell, which shields the metal below from any further interaction to its environment. The aging process of the metal comes to a near halt, with the hydroxide layer giving it both greater strength and longevity.

In general, there are two types of metal aging:

Natural aging: just as the name suggests, this is letting the metal age with time, in its natural environment. The strengthening benefits of aging will be more gradual but still effective.

Artificial aging: this refers to any method used to artificially accelerate the aging process. This is usually done through heat treatment of the metal alloys.

Both types do carry a risk of over-aging. This happens when the aging process pushes the metal past the point of strengthening into stressing and deteriorating it. As you might expect, this is more likely to occur with artificial aging: either because the metal has already undergone the aging process, or the heat applied is too intense or prolonged. However, when properly carried out, metal aging is a great benefit to the finished product.

Decoding Steel by its Numbers

Like any other field of expertise, the steel industry has its own jargon – one that may be confusing upon first encounter. Why are they assigned four-digit codes? What’s the difference between Alloy 4130 and 4140?

Steel is sorted into four main categories as set by the AISI (American Iron and Steel Institute):

  • Carbon steel
  • Alloy steel
  • Stainless steel
  • Tool steel

Being steel, these contain the same two basic elements of iron and carbon. Determining their category depends on the percentage of carbon and other alloys added to the iron, which changes the properties of the finished metal.

Within each category, steel can then be classified according to type. This usually includes several of the descriptive factors below:

  • Composition: the main categories of carbon, alloy, stainless, and tool steel.
  • Microstructure: these are the subcategories of composition. For instance, stainless steel can be classed as ferritic, austenitic, martensitic, and duplex steels.
  • Method of production: two methods account for almost all modern steel production, known as EAF (electric air furnace), and BOS (basic oxygen steelmaking).
  • Form/Shape: also known as primary forming, creating shapes such as plate or bars.
  • Method of finish: this is referred to as secondary forming, the techniques which give the final product its properties and finish. This can include processes such as hot and cold rolling, tempering, or galvanizing.
  • Physical strength: using ASTM (American Society for Testing and Materials) standards, the designation typically includes a letter prefix and assigned number.

There are two primary numbering systems used to classify metals, so steel descriptions typically will include both. Along with AISI, the numbering system set by SAE (Society of Automotive Engineers) is most used in the metals industry. For the most part, SAE has adapted their system to align with the classifications set by AISI, so that specifications are standardized for steel.

So with this information, consumers have the ability to recognize the category and classification of a steel item. In the four digit code system, the first number will determine the type:

Starting with 1: Carbon steel

2: Nickel steel

3: Nickel-chromium steel

4: Molybdenum steel

5: Chromium steel

6: Chromium-vanadium steel

7: Tungsten-chromium steel

8: Nickel-chromium-molybdenum steel

9: Silicon-manganese steel and other SAE grades

The following numbers then give additional detail to the specific type of steel. In most cases, the second digit indicates the percentage of alloying element. The last two digits are the percentage of carbon concentration within the steel.

So using the example of 4130 vs 4140 steel: both start with a 4, so they are molybdenum steels – with the concentration of molybdenum being 1%. The difference between the two is that 4130 has a carbon percentage of roughly 0.30%, while 4140 contains 0.40 percent carbon. Because of its lower carbon percentage, 4130 would be more easily machined and weldable than 4140. However, the higher degree of carbon in 4140 alloy gives it greater hardness and strength than 4130. Armed with this knowledge, this may better help you choose the right type of steel for your needs.

Uniform Metal Corrosion and Prevention

Corrosion is the deterioration of a metal due to an electrochemical reaction between the atoms on the metal’s surface and its surrounding environment. Most commonly, corrosion refers to oxidation: the process where a metal reacts to the oxygen in air or water. The most familiar example of corrosion is iron oxide (rust), but other metals can corrode in similar ways. Given sufficient time and exposure, corrosion will have a significant negative impact on the metal’s appearance, strength, and durability. If left unchecked, corrosion will eventually lead to the weakening or total disintegration of the metal parts. The World Corrosion Organization (WCO) estimates the annual cost of corrosion to be up to $2.5 trillion dollars – and that up to 25% of that damage is entirely preventable.

General Attack Corrosion, also known as Uniform Attack Corrosion, is characterized as the reaction occurring over the exposed surface area of a metal object or structure. This is the most common type of corrosion, leading to the greatest overall destruction of metal by tonnage. However, from a technical standpoint, it is also considered to be the ‘safest’ form of corrosion to encounter. The damage which occurs with general attack corrosion, being fairly uniform and predictable in its progress, means it is the easiest to diagnose and prevent.

How to Prevent Uniform Metal Corrosion

1. Selecting the Right Metal: The four basic types of metals referred to as “corrosion-proof”

Stainless Steel: This alloy contains iron, which easily oxidizes to form rust, and chromium, an element even more reactive to corrosion than iron itself. However, when chromium is added to steel, the corrosion which results then forms a protective layer on the surface of the metal. In contrast, corrosion which occurs on uncoated carbon steel will repeat continuously as the rust forms, wears off, and forms again. Eventually the rusting will lead to the metal’s disintegration. Iron oxide layer on stainless steel will resist further corrosion. This means the layer actually prevents oxygen from reaching the steel underneath. Corrosion-resistant in stainless steel can be further boosted by the addition of other elements in the alloy such as nickel and molybdenum.

Aluminum: Since aluminum alloys contain almost no iron, they are free from rust. The corrosion with this metal is similar to chromium in stainless steel; after the initial corrosion occurs, it creates a surface layer that protects the metal from any further damage. This film of aluminum oxide can be unsightly with dark marks or streaking, but as long as it remains, it will shield the underlying metal.

Brass, Bronze, and Copper: Like aluminum alloy, these metals contain little to no iron. They do react with oxygen – most noticeably with copper, which oxidizes to a distinctive green patina. The oxidized layer helps protect the copper from further corrosion. The other two metals combine copper with other metals, which makes them naturally corrosion-proof: copper and zinc to produce brass, and copper and tin for bronze.

Galvanized Steel: This is carbon steel that is galvanized, or coated, with a thin layer of zinc. Like chromium and copper, zinc is highly reactive to oxygen and will quickly begin to oxidize. This layer of zinc oxide prevents any further corrosion on the galvanized coating. Even more importantly, it acts as a barrier preventing oxygen from reaching the steel. Eventually, the zinc will wear off which will make the carbon steel vulnerable to rust, so this type of metal is not entirely corrosion-proof. However, it will take much longer to rust than untreated carbon steel.

2. Protective Coatings

In addition to galvanized steel, other coatings can be applied as a barrier between the environment and the metal. Painting is one of the most cost-effective ways of preventing corrosion. Powder-coating is another popular option. This involves applying a dry powder to the metal and then heating it to fuse it in an even, smooth film. Both methods work by creating a uniform physical barrier between oxygen and the metal.

3. Monitoring the Environment

Simply put, corrosion is the reaction of the metal with its surrounding environment. So whether the environmental factor is air, water, stresses placed upon the metal itself, or all of the above, regular maintenance and monitoring goes a long way towards preventing or lessening the impact of corrosion. Crevice corrosion, for example, is commonly found in areas where metals overlap each other. This means the metal parts are exposed to varying oxygen concentrations, leading to uneven wear and deterioration. Proper maintenance such as eliminating crevices when found, or ensuring complete drainage in vessels, can help to prevent this corrosion. In harsher environments, replacing parts and fastenings with higher alloys can help preserve the metal’s functionality.

All metals will corrode eventually, but the process does not necessarily need to be a destructive one. By anticipating how and where an item will be used, the choice of metal and its maintenance can prevent corrosion from becoming a serious problem. Corrosion prevention not only helps save equipment and money, but it will also help keep metals safer for the people who use them.

Stainless Steel Kitchen Remodel

Property and home improvement shows are more popular than ever – and according to those experts, a kitchen remodel is one of the most effective ways to maximize your budget for home renovation. Stainless steel’s durability and stylishness make it a great construction material and design element in a kitchen. Whether used to equip a sleek industrial space, adding modern touches to classic or mid-century design, or used for cookware and utensils, consider the benefits of using stainless steel to update your surroundings.

5 Reasons to Use Stainless in Your Kitchen

  • Durability: Stainless steel is the standard in the restaurant industry for good reason; it’s strong, rust-free, and resists heat damage! Grade 304, the most commonly available type of stainless steel, will hold up to the daily wear of food preparation and cleaning because it is a non-reactive metal. This makes it incredibly versatile for everything from appliances and cutlery to pots and pans. Metals like copper or aluminum will react to acidic ingredients such as vinegar, discoloring its shiny finish and adding unpleasant flavors to your food. Countertops made of stainless steel can hold up to heat, liquids, and cleansers without negative effects – the same treatment which can crack or stain granite surface
  • Low Maintenance: The addition of chromium to produce stainless steel makes it very resistant to oxidation, which can rust and wear down other materials. Whether it’s exposed to water in a kitchen sink, high temperatures in a barbeque grill, or the cold of a freezer, stainless steel requires little maintenance to keep it looking its best. Stainless steel cabinets will not warp, making them ideal for high humidity or outdoor cooking areas.
  • Style and Versatility: Despite what you may think, stainless steel is not simply for those who like minimalist or industrial design! It coordinates well with any color or décor and makes for easy matching between your appliances, fixtures, and pots and pans. Cabinets or countertops with a high shine finish can help brighten a dim kitchen area. Appliances made of brushed-finish stainless steel give an elegant glow. Blended with natural materials such as wood and stone, stainless steel helps to give a timeless yet modern look to your kitchen.
  • Hygiene: Stainless steel is a non-porous material. This means its surface doesn’t allow air or liquid to pass through, which prevents the growth of bacteria within the steel. So kitchen surfaces and implements can be easily and thoroughly cleaned. Stainless steel makes an ideal choice for kitchen sinks and backsplashes since it can hold up remarkably well to regular use, water, and household cleansers.
  • Eco-Friendly Material: Nontoxic, long-lasting, and recyclable: stainless steel makes an environmentally-friendly choice of material for your kitchen and home. When treated with care, the durability of stainless steel means your appliances, décor, and cookware will last for many years, preventing excess waste and landfills. The easy cleanup for stainless steel – just soap and water – helps to cut down on the use of chemicals. As consumer demand increases for sustainable choices, consider the advantages of building and outfitting your kitchen with stainless steel. Its long life makes it a good choice for your finances, and for the good of our communities.

FastMetals is your online supplier for Stainless Steel Sheet.  Talk to us about what you are planning for your home improvement, we do custom cutting to fit your specific needs. 

Aluminum Tread Plate

Aluminum Tread Plate can be utilized for your anti-slip surfaces

What is Tread Plate?

Rolled aluminum tread plate is made of an alloy, where elements such as copper or silicon are added to aluminum to increase its strength and corrosion resistance. The two of the most common grades of aluminum alloy include:

Alloy 3003: The most widely used of all aluminum alloys. Manganese gives the alloy up to 20% more strength over pure aluminum, while still allowing for good workability. While not as strong as 6061, aluminum 3003 tread plate’s shiny reflective finish makes it both functional and decorative.

Alloy 6061: 6000-series aluminum is mixed with magnesium and silicon, giving the metal a high degree of strength. This, along with its corrosion resistance and weldability, is why 6061 is often referred to as structural aluminum. Aluminum 6006 tread plate comes in a mill finish, which means its surface is untreated with little to no shine.

Uses of Aluminum Tread Plate

Tread plate, Diamond plate, Checker plate. No matter what the name, it all refers to the same product: metal sheet or plate with a regular pattern of raised diamond marks. When looking to keep workers safe on the job, aluminum tread plate is a durable, high-quality option to help reduce slips and falls. So why choose aluminum tread plate over other materials? It has numerous benefits including:

  • Slip resistance: The raised pattern provides traction even under tough weather conditions that can find surfaces covered in water or mud. For this reason, tread plate is typically used on stairs, ramps, loading docks and other industrial areas.
  • Corrosion resistance: Unlike iron oxidization, aluminum oxidization stops at the surface. Iron rust can be easily worn or flaked off, exposing fresh metal which rusts and leads to further deterioration. Aluminum oxidation, on the other hand, will not progress beyond the outside layer unless the oxide is removed. This makes well-suited to wear and tear, including exposure to corrosive elements like seawater.
  • Hygiene: Tread plate is easy to wash down, and the corrosion resistance of aluminum alloy means it can hold up to regular use of strong cleaning agents. This makes it ideal for areas needing regular heavy-duty sanitation, such as food processing plants, kitchens and walk-in freezers, and ambulances.
  • Protection: The design of tread plate gives impact and surface protection, coupled with the strength of solid metal. When used for corner guards and door plates, aluminum tread plate will help prevent unsightly marks or damage in high-traffic areas.
  • Decorative: Aluminum tread plate is often used for its decorative quality. Vehicle trim, shop walls, and furniture can be made of tread plate, most often in a bright polished finish. The high shine combines both form and function, with the shiny surface also helping with ease of cleaning.

FastMetals is your one stop spot to get tread plate.  Starting at .063 thickeness up to .375, FastMetals.com has you covered.  In size selection as small as 1 foot by 1 foot, all the way to 4 feet by 8 feet.  Need something really specific?  No problem – just submit a fast quote for a custom cut.

Hot Rolled vs Cold Rolled, So much to know

Is one a better choice for your project?

What type of rolled steel would make the better choice for your project? It’s important to understand the fundamental differences between hot and cold rolled steel in order to select the best one for your needs.

Rolling is a metalworking process where the metal is passed through one or more pairs of rolls, which reduces thickness and makes the material uniform throughout the roll. Imagine the steel as if rolling dough through a pasta-maker, flattening and thinning it out until you have an even, smooth product.  The two types of rolling are hot and cold, which is determined by the metal’s temperature during processing. Hot rolling occurs when the metal is heated above its recrystallization temperature. Cold rolling is when the metal is processed while below the recrystallization point.

Hot Rolled Steel

Hot rolling involves rolling the steel at a temperature point above its recrystallization temperature, typically around or above 1700 degrees F. This means the steel can be shaped and formed easily, including producing much larger sizes. Since the manufacturing can be done without pauses or delays in the process, this means hot rolled steel is typically cheaper than cold rolled steel.

Because of the high processing temperature, the hot rolled steel will have a rougher, scaly finish and will also shrink slightly as it cools. This means the finished product can vary in its size and shape dimensions, and at a lower price point than the same item produced through cold rolling. Hot rolled steel is best suited for uses like welding, railroad tracks or construction, where precise shapes and tolerances may not be required.

Cold Rolled Steel

Cold rolled steel is manufactured below its recrystallization temperature. Essentially, it’s hot rolled steel with additional processing in cold reduction mills. Because it is typically produced around room temperature, the process allows for closer dimensional tolerances and a wider range of surface finishes for the steel.

‘Cold rolled’ is often mistakenly used to describe all steel products, but it refers specifically to the rolling of flat rolled sheet and coil products. For other steel shapes produced below the recrystallization temperature, the accurate terminology is “cold finishing”. For instance, a cold finished steel bar is produced by cold drawing (pulling) the metal, then turning, grinding and polishing. This produces a much more precise end product with four advantages:

  • Increased yield and tensile strength
  • Fewer surface imperfections due to the turning process
  • Grinding gives closer size accuracy and precise shapes
  • Polishing improves the surface finish

The exception is cold rolled sheet versus hot rolled sheet. For this particular product, the cold rolled steel has a low carbon content and is typically annealed (heat treatment to increase ductility). This means cold rolled sheet will be softer than hot rolled sheet.

Overall, cold rolled and cold finished steel is superior to hot rolled steel in finish, straightness and tolerance, and comes at a higher price point. It would be the recommended choice when visual appeal is a priority for your project. Typical uses include building materials for sheds and garages, metal furniture, and home appliances.

Buy Hot Rolled or Cold Rolled Steel

Here at FastMetals we offer a range of Hot Rolled and Cold Rolled steel products – we offer great quality product, reasonable pricing and fast shipping – shop online at FastMetals.com or call us toll free at (833) 327-8685.