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An Essential Guide to Stainless Steel

Published by Rapid Metals on

Stainless steel is one of the most common metals in the world. You likely use it every single day, but you might not even realise it. In terms of metal, stainless steel is relatively new discovery, which makes its explosion in commercial use even more impressive. 

We’ve put together a handy guide on stainless steel which will tell you everything you need to know about this incredibly versatile and prolific metal. 

What is Stainless Steel?

Stainless steel is a type of steel alloy. It typically has a chromium content of around 10.5%, and this is what gives it its corrosion-resistant properties. There are different grades of stainless steel to suit different applications, but overall, stainless steel is a multifunctional material that is commonly used across all types of industries. 

Types of Stainless Steel

As mentioned, there are different grades of stainless steel which will dictate the manufacturing process. As a base, all stainless steel is made up of carbon, iron and chromium. Different components can be added to change the properties of the steel. These properties make up the four main stainless steel families: 

  • Austenitic
  • Ferritic
  • Martensitic
  • Duplex

Austenitic 

Austenitic stainless steel has a high chromium content, and it also contains nickel, nitrogen and manganese. The microstructure of austenitic stainless steel takes a cubic face-centred crystal composition. This means no matter how much the steel is heated – even to melting point – its hardness will not be altered through heat alone, but it can be done through cold work hardening. This is one of the features that makes austenitic steel so common in the use of things like cookware. Austenitic stainless steel is non-magnetic and highly weldable, too. 

Ferritic 

Ferritic stainless steel is comprised of a ferrite body-centred cubic crystal structure. It contains little to no nickel, a high level of chromium, and smaller amounts of carbon. It is magnetic, but the lower carbon content means it’s not quite as strong and austenitic steel. Ferritic stainless steel can’t be hardened through heat. It is commonly found in car exhaust pipes and roofing materials. 

Martensitic 

Martensitic stainless steel has a lower chromium content compared to the other three main families, meaning its corrosion-resistant properties are compromised. The increased carbon content in martensitic steel means that unlike ferritic and austenitic steels, it can be hardened through heat treatment. This makes it stronger than other types. When anodised, martensitic stainless steel is often used in the production of surgical instruments.

Duplex 

Duplex stainless steel is a 50/50 or 60/40 mix of ferrite and austenitic steel compounds. It can contain up to 32% chromium content, and typically has around 5% molybdenum content, too. This means duplex steel is twice as strong as austenitic steel, and it offers an exceptionally high level of chloride stress corrosion cracking resistance. For this reason, duplex steel is commonly used within the oil and gas industries. 

Benefits of Stainless Steel 

There are various properties of stainless steel that make it a go-to choice for all manner of applications, but it’s most widely known benefit is that it offers a good level of resistance to corrosion. The chromium content essentially forms a film over the steel, and this prevents it from rusting. The structure of stainless steel also means it is resistant to heat, making it ideal for a range of industrial and domestic uses. 

Another benefit of using stainless steel is that it looks better aesthetically, and it requires far less maintenance due to the chromium content. This makes it ideal for industrial applications. 

The durability of stainless steel, paired with its high tensile strength, are two highly attractive properties, especially given how strength can be achieved with a lower weight. This means less material needs to be used to achieve high quality results. 

Stainless steel is known for being easy to weld and mould. This means it can be formed into intricate shapes, hence why it’s a common choice for cutlery and machine parts. 

Add to this the fact that stainless steel is 100% recyclable, and around half of all stainless steel in circulation is made from recycled stainless steel, its sustainability makes it an even more attractive material because of its neutral effect on the environment. 

What Can Stainless Steel be Used For? 

Stainless steel can be used for all manner of things spanning multiple industries. It’s commonly used for domestic purposes, especially in kitchens. Sinks, taps, and appliances such as fridges and ovens often have stainless steel exteriors. It’s easy to clean and disinfect, as well as being heat resistant and incredibly durable, making it an obvious choice for kitchens. 

The sterile nature of stainless steel also makes it ideal for medical settings. It’s commonly used for medical trays, as well as dental and surgical equipment. Implants such as hip replacements are often made from stainless steel, as are parts for MRI machines. 

The strength of stainless steel sees it often being used in the building trade, be it for cladding or handrails. Being so easy to weld and resistant to corrosion, it’s also increasingly becoming a statement feature in architecture.

Stainless steel is used across all types of transport, including rail, automotive and aviation. Car exhausts and trims, shipping containers, jet engines and landing gear all commonly rely on stainless steel. There’s almost nothing it can’t be used for. 

Where to Buy Stainless Steel 

At Rapid Metals, we supply stainless steel available to buy online for delivery across the UK up to 3m in length. You can choose from angles, box sections, flats, hexagons, rounds, tubes, sheets, and squares. We have a wide selection online, but if you can’t find what you need, or if you need advice on if stainless steel is the best option for you, please contact us.

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