Which stainless steel is right for the job?
Most people don’t have to worry too much about what grade of stainless steel they choose – a nice, brushed finish for the cooker hood, a good shine on the cutlery, and they’re happy.
If you’re in construction you have to be more discerning. Choosing the right grade of stainless steel for your project is a must. But what is it that makes the difference? What exactly do those grade specifications mean? And what other factors should be considered when choosing stainless steel components?
Let’s start with the chemistry.
The basics
Grade 304 stainless steel is made up of 18-20% chromium and 8-10.5% nickel.
Grade 316 stainless steel contains 16% chromium, 10% nickel, and an added element of 2-3% molybdenum.
Both grades are versatile. Grade 304 is resistant to many chemical and acidic substances. It’s attractive and durable making it a popular choice for things like handrails and balustrades.
Where corrosion resistance is required, Grade 316 is preferable. The molybdenum gives Grade 316 superior corrosion resistance and it’s less likely to suffer pitting and crevice corrosion. What’s more, the molybdenum gives Grade 316 steel a higher level of polish and shine. But, of course, the superior performance has a cost implication. Grade 304 in the right environment is a strong, durable and more affordable option.
The application and the environment
It always pays to understand both the application and the environment. It’s too easy to assume that away from marine or coastal settings, corrosion isn’t an issue. Industrial sites may discharge acidic condensates. Winter salting of roads may be an issue in an urban setting. Conversely, in locations where temperatures and humidity tend to be lower, the risk of corrosion may be reduced.
Other considerations
Component design is important. Crevices can trap salts and water, leading to corrosion. Fixings that create moisture traps should be avoided as should aluminium fasteners.
It’s also important to understand how buildings will be maintained. Higher-grade steels may be more appropriate when cleaning and maintenance are expected to be infrequent or challenging.
Grades 304 and 316 also have thermal expansion rates higher than most carbon steels. Expansion joints and sealants must allow for this.
More guidance
This is only a brief introduction to the subject of stainless steel. Do get in touch if you’d like to know more. Our Paradigmeexperts will be very happy to discuss any construction challenge and help you make the right choice.
