weathering steel

Weathering Steel: What is it?

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.

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.

Stainless Steel 304 and 316: What’s the difference?

Stainless steel 304 and 316 are the most widely used types of stainless steel. It can be difficult to visually, and sometimes characteristically, tell the difference between the two types of steel. So, what is the difference?

The biggest difference in the types of steel is the presence of molybdenum in stainless 316. Molybdenum is a metallic element that resembles chromium and tungsten in most characteristics. It is especially used for the strengthening and hardening of steel. The most common make up of stainless 316 is 16% chromium, 10% nickel, and 2% molybdenum – whereas stainless 304 is typically 18% chromium and 8% nickel. The molybdenum is added to stainless 316 to help resist corrosion to chlorides.

Stainless 304 has excellent resistance to corrosion and rust, but may be susceptible to corrosion from chloride solutions. Stainless 316, however, is ideal for applications that will be exposed to marine, pharmaceutical, and chemical elements.

The infographic below explores more of the differences, and similarities, between the two types of stainless steel.

For more information on which type of stainless steel you should choose for your next project or application contact your local sales representative. You can also find more information on how stainless steel is made here.

Stainless Steel 304 and 316: What’s the Difference?

Stainless Infographic