So you have a project, and you want to use a familiar, readily available material. You know your decision boils down to 303 vs 304 vs 316 stainless steel. You want an end product of the best possible quality, but you have to watch costs. Using less expensive components lets you (if you choose) pass on savings to the end user.
Here are the facts about the three grades of stainless steel vying for your approval. Armed with a little data, you can save time selecting materials, not to mention save the tension that results if you make a bad material choice.
303 Vs 304 Vs 316 Stainless Steel
First off, what do 303, 304, and 316 stainless steels have in common? Well, they resist corrosion and look great, always good things. They're also austenitic, so they're made with 15% to 30% chromium and 2% to 20% nickel. As a result, they have good:
- Surface quality
- Wear resistance
- Impact resistance
For the most part, they're nonmagnetic. These factors help explain why these stainless steels, especially 304, are among the most-specified grades.
Despite all these similarities, the differences are still notable. The three grades work best in different applications -- like athletes playing different sports, they all have slightly different “skill sets.”
This fact alone can make up-front cost considerations less important than long-term cost-effectiveness. Simply put, 316 stainless costs more than 304 and, somewhat counterintuitively, 303 costs more than 304.
Where and Why Do 303, 304, & 316 Stainless Work Best?
The applications for 303, 304, and 316 stainless steel are not mutually exclusive. There's a fair amount of crossover. But it's also clear that one grade will work better than another in a particular environment. Here's a quick rundown:
1. 303 Stainless Steel
This grade gets down to the nuts and bolts -- really. Besides chromium and nickel, it contains selenium or sulfur, so it's highly machinable. This composition makes it ideal for corrosion-resistant, strong, long-lasting fasteners. It's also the choice for aircraft fittings and gears as well as bushings and other small components.
It's not as corrosion-resistant as 304 stainless steel, but it still stands up well, and the machinability at least partially makes up for the difference. Welding, however, doesn't work well with 303.
2. 304 Stainless Steel
Accounting for about 50% of all stainless steel in the world, 304 is a workhorse for good reason. It's great at resisting corrosion, and it's weldable.
Of course, it's not perfect. In a high-chloride environment, such as near the ocean, it tends to pit. But it's otherwise tough, strong, and lasting.
Applications for 304 stainless steel include places where beauty and/or cleanliness are important, such as:
- Architectural projects
- Food processing plants
3. 316 Stainless Steel
Here's where the higher cost can pay off.
If your project involves a high-chloride environment, 303 and 304 stainless steel are probably not the best choices. But 316 will work and be cost-effective in the long term.
What makes the difference? Molybdenum. Just a little, maybe 2% to 3% added to the mix, increases corrosion resistance significantly.
This stainless steel should be in consideration for any project that might come into contact with chloride, including:
- Marine architecture
- Food processing systems
- Hot water systems
The Right Stainless Grade for the Right Place
Now you have some concrete support for your choice of stainless steel, but there's more. You can talk to your manufacturer about design-stage specifics like material choice.
We also have helpful charts for choosing the right metal for your project:
The key is to make the right choice for the application without making price the sole or even the most important consideration. In the long run, you and your customer will be happier with the result.