316 Vs 316l Stainless Steel: Strength, Welding, And Selection

The defining difference between 316 and 316L stainless steel is the Carbon content. Standard 316 stainless steel has a maximum carbon content of 0.08 percent, while 316L (where “L” means Low Carbon) pushes that limit to 0.03 percent.

In practical applications, this subtle difference in chemical composition directly determines an important principle of use: if you want to weld thick materials and want to avoid weld corrosion, you must use 316L.

But things are not so absolute. If your application scenario involves structural load-bearing at high temperatures, 316L is actually the weaker side in terms of mechanical properties.

So, is 316L the 316 “upgraded version”? I don’t think so. Although it solves the big trouble of weld corrosion, blindly replacing standard 316 with 316L may bring new risks in terms of tensile yield strength and high temperature stability.

Next, I’ll tell you about the key data, the practical problems of processing and manufacturing, and a “double-brand certification” industry secret that can help you save the project budget.

Chemistry & Mechanical Properties

We look directly at the provisions of the ASTM A240 standard:

Technical Parameters	316 Stainless Steel (Standard)	316L Stainless Steel (Low Carbon)	Engineering Interpretation
Carbon Content (Max)	0.08%	0.03%	316L low carbon characteristics, is to prevent the occurrence of carbide precipitation during welding.
Yield Strength (Min)	30,000 psi (205 MPa)	25,000 psi (170 MPa)	It is obvious and the 316 is stronger. 316L sacrifices part of its strength for weldability.
Tensile Strength (Min)	75,000 psi (515 MPa)	70,000 psi (485 MPa)	At ultimate failure load, the 316 still maintains a slight advantage.
Maximum Service Temperature	Good >800°C	Avoid >425°C	In terms of high temperature creep resistance, the 316 performs better.

My professional interpretation:
Pay special attention to the drop in yield strength of 316L. In my experience, in some high-pressure pipeline or structural support projects, this 5,000 psi yield strength difference may be the difference between passing and failing the ASME pressure vessel code. Therefore, do not take it for granted to replace the 316 with 316L on the structural drawings without re-calculating the stress.

Welding and Machining

Judging from our usual experience in dealing with processing plants, choosing these two grades has a great impact on your production process.

“Intergranular Corrosion” phenomenon (Weld Decay)

What happens with 316: When you weld standard 316, the area next to the weld (we call it the “heat affected zone”, HAZ) is affected by high temperatures. If the carbon content of the material is high (for example, close to 0.08 percent), the carbon will “steal” the chromium in the alloy and form chromium carbide. This causes the chromium content in the heat-affected zone to fall below the 10.5 percent required to maintain its rust resistance, making it highly susceptible to intergranular corrosion. Many times, you must perform a “solution annealing” treatment (that is, reheating the entire workpiece) after welding to restore its corrosion resistance—this process is expensive and time-consuming.

What happens with 316L: Its low carbon (0.03 percent) nature prevents this reaction at its source. You can safely weld and use it after welding without worrying about corrosion.

Machinability

Although 316L is softer because of its low carbon content, it sometimes feels a bit “sticky” when machining, and the chips are relatively long, which is easy to block the tool. But then again, thanks to the advancement of modern smelting technology, for the processing of some complex parts, the current 316L is usually considered to be easier to handle than the harder standard 316.

The “Dual Certified” Solution

Well, speaking of which, I have to mention a semi-open secret in the industry. Due to the popularity of modern steelmaking technologies (such as AOD/VOD refining), most stainless steels produced on the market today actually meet both the low carbon standard of 316L (C < 0.03%) and the high strength requirement of 316. This is usually achieved by adding a trace amount of nitrogen to the molten steel.

Next time you get the material, you might as well look at its material inspection report (MTR). If it says 316/316L dual grade certification (Dual Certified), it means:

• Its carbon content is less than 0.03 percent (it can be welded safely).
• Its yield strength is higher than 30,000 psi (structurally strong enough).

My suggestion is: in procurement and inventory management, as far as possible, unified designated procurement of “316/316L dual grade certification” materials. This essentially eliminates the risk of mixing materials to the satisfaction of both the welder and the structural engineer.

When to Strictly Stick to Standard 316 (Non-L)

There is a particular scenario where it is dangerous to use a grade with an “L”. If your equipment needs to operate at temperatures above 500°C (930 °F), such as in steam systems or industrial furnaces, the low carbon characteristics of 316L can significantly reduce its creep rupture strength (i.e., the material’s ability to resist long-term tensile deformation at high temperatures).

Rule of thumb:

• High temperature environment (>500°C) = Standard 316 is preferred (or 316H, a high carbon version).
• Corrosive wet environment (<500°C) = 316L is preferred.

Quick Selection Summary

To ensure that your project is long-term and reliable, keep these points in mind:

• For any application involving welding, 316L is preferred to avoid the major pitfall of intergranular corrosion.
• If you are building a pressure vessel, be sure to check the yield strength; unless it is dual-grade certified, 316L is not as strong as 316.
• Check whether there is a “316/316L” logo on the material certificate, which allows you to have excellent weldability and sufficient mechanical strength at the same time, which is regarded as taking up the benefits of both ends.

About the Author：James Wilson

I am a Senior Application Engineer with over 20 years of experience in metallurgy and industrial fabrication. Having spent decades in the petrochemical and marine sectors, I have analyzed countless equipment failures caused by improper material selection. My goal is to bridge the gap between complex ASTM standards and the welding shop floor, helping engineers and makers choose the exact steel grade needed for safety and longevity.