One of the most crucial decisions any manufacturer must make is selecting the optimal material for a given application. Many years ago, that choice might have been relatively easy, choosing between steel and aluminum, for instance. But with the increasing diversity of metal alloys, modern-day materials have an ever-growing list of very specific properties available. It makes picking the right stainless steel more difficult than ever.
Two of the most popular and versatile stainless steel alloys are 304 and 316. Anyone who works with stainless steel needs to understand the differences between these two workhorses of the industry, in order to know which applications they are best suited for.
What Are The Key Properties Of 304 Stainless Steel?
SAE 304 stainless steel is probably the most common stainless steel alloy in use today. Like 316, it is an austenitic stainless steel, meaning it is a metallic, iron allotrope. It is not as conductive, both electrically and thermally, as carbon steel and it is not magnetic.
The most essential characteristic of stainless steel is its corrosion resistance. 304 alloys, like all stainless steel, offer excellent resistance in a wide range of atmospheric environments. However, it can be susceptible to pitting and crevice corrosion in chloride environments. There is also a problem with stress corrosion cracking in temperatures greater than 60 °C. Seawater, in particular, can have a detrimental effect on the longevity of the metal, and this is the main difference between it and 316 stainless steel.
304 stainless steel is also celebrated for its excellent machinability and formability. This alloy is suitable for applications that involve stamping, such as for sinks and saucepans. Thanks to its low yield strength and high elongation, 304 can be easily formed into a variety of complex shapes. Making it, even more, cost-effective, after shaping, the metal hardens quickly and can be air-cooled. Another benefit is that after forming, stress relief annealing can be performed for further enhancements.
304L stainless steel also offers excellent weldability, which makes it a top choice for commercial welding applications. This includes fusion and resistance welding. It’s important to note that when you are forming 304 stainless steel, uniform temperatures are needed, generally between 2300°F and 1700°F.
Besides corrosion resistance, the property that is probably most responsible for 304’s popularity is its versatility. 304 stainless steel is currently adopted in an extremely wide range of applications. There’s practically no industry that doesn’t feature many examples of 304. For most comparable materials, intergranular corrosion becomes an issue when dealing with stress relieving or welding, but this is not the case with 304L. And although it can’t be heat treated, this alloy can be hardened and strengthened through a cold working process.
What Are The Key Properties Of 316 Stainless Steel?
Following SAE 304, SAE 316 grade stainless steel is the second most common in commercial use today. Also, an austenitic stainless steel, the key difference in its molecular makeup, which like 304 contains significant amounts of chromium and nickel, is the addition of approximately 2 to 3 percent molybdenum.
The addition of molybdenum means that it has even greater corrosion resistance than 304. It is much more protected from the deleterious effects caused by exposure to chlorides, and can even resist the general corrosion of sulfuric acid and the like. This has made 316 a go-to material in the chemical and petrochemical industries, as well as in pharmaceuticals and food processing. It is also popular for wastewater treatment facilities and any marine application or architectural structure that is near the sea.
When just doing a visible comparison of the two materials, it is nearly impossible to discern any differences. The only way to be positive which is which is to conduct a material test report that analyzes the chemical make up of the alloy. That’s how similar these two grades are.
There is one more key difference between the two materials: cost. Due to the increased nickel and molybdenum, 316 is significantly more expensive. For most applications, the cost difference is not worth it, as 304 performs just as well. But for applications that will be exposed to chloride, such as marine structures, the price difference is fully justifiable as it will more than pay for itself with the increased longevity.
Which Applications Are Best Suited For 304 And 316 Stainless Steel Alloys?
As previously mentioned, 304 and 316 are the two most common stainless steel alloys available on the market today. 304 can be found in all manner of applications, across a wide variety of industries. This includes refrigerators and dishwashers, food processing equipment, pipes, heat exchangers, machinery parts, automobile headers, architecture, and vaporizers.
The greater expense of 316 means that it is used pretty exclusively in applications that depend on its increased corrosion resistance. Examples include chemical processing and storage equipment, refinery equipment in the petrochemical industry, medical devices, and structures and buildings that are found in or next to marine environments.
No matter which material you choose, you can rest assured that you will benefit from the many attractive properties of stainless steel in addition to its corrosion resistance. Whether it’s the aesthetic appearance, durability, strength, or ease of fabrication, there’s a stainless steel alloy that is perfect for your job.
Clinton Aluminum strives to be more than just a material supplier. Our goal is to work closely with our clients throughout the entire production process, helping share our knowledge of industry best practices. This is made possible because the members of our sales team and our warehouse managers have an average of nearly 13 years working for Clinton. You can rest assured that our team understands the challenges you face and can help you achieve your goals.
Clinton Aluminum is the Midwest’s leading supplier of aluminum and stainless steel products. Please contact us today to learn more about how Clinton Aluminum can help make your business more competitive!