The world of stainless steel grades can get pretty interesting.
While there’s a stainless steel grade for almost every application, it’s not always so simple. For some grades, there are variations. Such is the case in the 316 stainless steel series.
As one of the most commonly used stainless steels, the 316 series has two primary types -- 316 and 316L.
When selecting 316 vs. 316L for your project, it’s critical to understand the alloys’ similarities and differences.
What makes 316 and 316L stainless steels different from one another? The answer is surprisingly simple.
It's the carbon content. Stainless steel grade 316 has a max carbon content of 0.08%. 316L stainless has a max carbon content of 0.03%.
How do you remember which is which? 316L has a Low carbon content.
Note these are the same materials as SS316 and SS316L, as well as AISI 316 and 316L. No matter how you slice it, the "L" is the difference.
To understand what makes both alloys different, it’s important to first understand what makes them similar -- and it’s not just a shared number.
Both stainless steels share characteristics on four important fronts:
For applications where chloride exposure is part of the job, both 316 and 316L boast excellent corrosion resistance. That’s because both grades composition, which include nickel and molybdenum, allow the alloys to stand up to acids and chloride without compromise. Because of their superior corrosion resistance, both metals are one of the few considered a “marine grade stainless steel.”
Both stainless steels are considered stronger alloys. With their nickel content, they’re able to be fabricated at colder temperatures, and maintain ductility whether they’re roll formed, drawn, or bent. When heat enters the equation, they’re non-hardenable and can easily be passed through a die for shaping.
Both alloys are well suited for welding. Both stainless steels don’t succumb to cracking from extreme heat as other metals do when welded.
Despite one version having less carbon, both stainless steels cost about the same.
While both stainless steel alloys are indeed similar, their carbon content does allow for some nuances in two key categories: corrosion resistance and weldability.
Corrosion Resistance: In choosing between 316 and 316L stainless steels, the latter has a slight edge over the former. In other words, with its lower carbon content, 316L lasts longer in high-chloride environments. Compared to 316ss, 316L steel has better resistance to pitting and crevice corrosion over its useful life.
Weldability: After being welded, 316 is more vulnerable to weld decay than 316l because of its higher carbon content. However, this is only an issue if the metal needs to be welded over a period of several minutes or it's heated to temperatures between 425-815º C.
Overall, both steels are highly durable, corrosion-resistant, and perform well under high stress conditions.
Because of the aforementioned qualities, the 316 stainless steels have a variety of uses, including:
If you're not sure which type of steel is best for your project, here's the biggest thing to remember: if your project requires lots of welding, 316L steel is a better choice. However, 316 can be annealed to resist weld decay if you're set on this grade.
If you're looking for a cheaper material, 304 and 304L are physically similar to the 316s (slightly less durable) but cost a little less. If you're looking for highest durability, 317 and 317L have a higher molybdenum content, which increases their overall corrosion resistance.
Take a deeper dive into stainless steel grades with our downloadable Stainless Steel Grades Chart. Download it here:
(Editor's note: This article was originally posted in July 2016 and was recently updated.)