Metal West Stainless Steel Supplier

Cold Rolled: How it is Made

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We recently discussed how hot rolled steel is made. Now it only makes sense we talk about cold rolled. Cold rolled is the next step along the line of flat-rolled steel products. The process starts with hot rolled P&O.

Hot rolled is processed to a final thickness that is heavier than most sheet products. A cold-reducing process is used, which results in a thinner thickness. The cold reduction starts with tension to the sheet. This causes the product to become thinner, obviously, but also harder and more difficult to form.

Because formability is important in fabricating sheet metal, the steel is annealed. The process of annealing consists of a heat treatment that changes the properties of the material to increase ductility. Doing this makes it a great product for the customer.

Let’s go a little more in depth shall we?

The Cold Reduction Process

So, you are looking for cold rolled coils? Well, to achieve it hot rolled P&O is sent through a series of tandem rolling mill stands (4-high or 6-high vertically stacked rolls). As the material exits each stand it is a fraction thinner than the original hot rolled P&O When it leaves the last stand the material is recoiled. However, at this point the material is hard, not easily formable and basically unusable for many applications.

OK, how do we make it usable?

The Annealing Process

To soften the steel it goes through the annealing process. The annealing process can be accomplished in two ways, batching and continuous annealing. Batch annealing involves stacking the hard coils four or five high on fixed bases or stools (hence the name “batch”). The material is covered to allow the coil to be concealed from the oxides in the atmosphere. These oxides can potentially damage the surface finish.

A large furnace is then lowered onto the stacks of coil. The space between the cover and the furnace is heated by gas while the inside of the cover is fan circulated to convey heat to the coils.

The next method of annealing is continuous. This method allows for the material to be sent through a furnace in a continuous rolled strip. It is then cooled and recoiled.

The heating of the material causes it to become softer and allows for better formability to be used in various applications. It is now usable.

Cold Rolled Finishing

cold rolled lighting fixturesNow what? The material needs to be finished to ensure it is desirable for the customer. After the annealing processes the material is kept covered to prevent oxidization while it is still at a high temperature. This also allows for the breakdown of oils and vapors that may be present after cold rolling.

The material then undergoes temper rolling. The process of temper rolling consists of cold rolling the material with a very low reduction. This finishing process helps with surface finish and flatness of the final cold rolled product.

The finished cold rolled coil is delivered to service centers, like Metalwest, for processing and then sent to customers for fabrication of metal furniture (typically office use), motorcycle exhaust pipes, lighting fixtures and many more.

Cold rolled can also be sent through further processing to create galvanized, galvannealed, electro-galvanized and GalXC. All of which we will discuss later.

Steel Products Metal West

Weathering Steel: What is it?

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Weathering steel, commonly referred to as A606 steel, has recently gained popularity in the architectural world for its distinctive orange-brown oxide (or rust) finish. This layer of rust aids in the resistance to corrosive elements. When weathering steel is produced, it is not rusted. It gradually develops the rust-like appearance as it is exposed to the elements over time.

But, how does it develop the layer of rust and how does that actually aid in corrosion resistance? Let’s find out!

How Weathering Steel Works

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Unlike most corrosion resistant steels that resist rust, weathering steel does rust. However, it only rusts on the outer layer and will not penetrate into the steel once the initial layer has formed. With weathering steel, the layer of rust acts as a barrier to protect the steel from corrosion, whereas with other metals the rust is porous and breaks off allowing another layer to form. The specific alloying elements in the steel produce a stable layer of rust that adheres to the base metal and isn’t as porous as typical rust.

Benefits of Weathering Steel

Weathering steel has many benefits, which make it ideal for architecture.

  • Resists further rusting and staining
  • A high strength low alloy steel (HSLA)
  • Heat and corrosion resistant
  • Ease of formability
  • Low maintenance
  • Long-term performance
  • Environmentally friendly and can be recycled

What is Weathering Steel Used For?

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Because it is corrosion resistant, weathering style is frequently used for exposed structures. These can include bridges, building siding and roofing panels, truck and bus frames, as well as metal sculptures. It was initially used in the 1930s for ore wagons to help them resist corrosion. With its unique finish, it also eliminates the need for repainting or recoating of the steel.

There are elements that weathering steel can’t withstand, however. It shouldn’t be used for applications that will be exposed to chlorine. Chlorine will cause the rusted surface to corrode and can lead to premature failure of the material.

At Metalwest we stock A606 Type 4 in coil and sheet. For more information on product availability, contact your local sales representative as it may very between branches

Is Stainless Steel Magnetic? It Depends.

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Have you ever wondered why you can stick a magnet on one stainless steel fridge, but not another? They are both stainless steel, so why doesn’t it stick to both? Well, the answer is in the makeup of the steel. So, let’s see if stainless steel is magnetic.

Is Stainless Steel Magnetic? The Type of Stainless Plays a Role

Ferritic

There are different families of stainless steel and all have different physical properties. A less expensive stainless steel would be considered a ferritic steel. Ferritic stainless steels typically have better engineering properties than their counterpart, austenitic, but have reduced corrosion resistance due to lower nickel and chromium content. This makes ferritic stainless steel magnetic.

Ferritic steels provide an advantage in many applications in which thinner materials or reduced weight are required. They are also non-hardenable by heat treating.

Typical applications for ferritic stainless steels include automotive and truck exhaust systems, catalytic converters, agricultural spreaders, heat exchangers, kitchen equipment, and roofing just to name a few.

Ferritic metals are classified in the 400 series. At Metalwest we commonly stock 409 stainless and 430 stainless steel products.

Austenitic

Austenitic stainless steels are the more common types of stainless. These grades have higher chromium and nickel content. The higher nickel content makes austenitic grades non-magnetic.

Austenitic steels are similarly non-hardenable by heat treating, but also have excellent formability and higher corrosion resistance.

These type of steels are commonly used for kitchen equipment, appliances, automotive trim, architectural applications, chemical equipment, pharmaceutical equipment, and much more.

Austenitic stainless steels are classified in the 200 and 300 series. At Metalwest we commonly stock 201 stainless, 301 stainless, 304/304L stainless, and 316/316L stainless steel products.

So, the next time you are shopping for a refrigerator be sure to bring a magnet. Higher quality (and typically more expensive) stainless steel appliances will not hold your alphabet magnet set. But unless you plan on placing your fridge out in the elements, you will most likely get along just fine with a ferritic stainless steel appliance. It’s still stainless after all.

For more information about our stainless steel products, contact your local sales representative.