316 vs 316L Stainless Steel: What's the Difference?
MetalNow · October 20, 2026
The short answer
The only difference between 316 and 316L is carbon. 316 allows up to 0.08% carbon, and 316L caps it at 0.03%. Everything else, including the chromium, nickel and molybdenum that make 316 such a good marine-grade stainless, is the same.
That small change matters most when you weld:
Pick 316L if you're welding the part, especially thick sections, or if it'll see corrosive service after welding.
Pick 316 if you aren't welding and want slightly higher minimum strength, or if the part runs hot for long periods.
Not sure? Ask for dual-certified 316/316L. It meets both specs, and it's what most distributors stock anyway.
The rest of this guide covers why the carbon matters, how the two grades compare on paper, and which one fits common jobs.
316 vs 316L chemical composition
Here are the limits from ASTM A240, the standard spec for stainless plate, sheet and strip. Carbon is the only element that differs.
What's different:
316 (UNS S31600): carbon 0.08% max
316L (UNS S31603): carbon 0.030% max
What's identical in both grades:
Chromium: 16.0–18.0%
Nickel: 10.0–14.0%
Molybdenum: 2.0–3.0%
Manganese: 2.00% max
Silicon: 0.75% max
Phosphorus: 0.045% max
Sulfur: 0.030% max
Nitrogen: 0.10% max
Iron: balance
The molybdenum is what sets the 316 family apart from 304. It improves resistance to pitting and crevice corrosion, especially around chlorides like salt water, de-icing salt and many cleaning chemicals. Both 316 and 316L have the same amount. For more on that comparison, see our guide to 304 vs 316 stainless.
Why carbon matters: welding and sensitization
Stainless stays stainless because chromium forms a thin, self-healing oxide layer on the surface. Anything that pulls chromium out of the metal weakens that protection.
Heat does exactly that. When austenitic stainless spends time between roughly 425–815°C (800–1500°F), carbon combines with chromium and forms chromium carbides along the grain boundaries. The metal right next to those boundaries is left short on chromium. This is called sensitization. In a corrosive environment, those chromium-poor zones can corrode from the inside out along the grain boundaries. Welders call it weld decay, and it typically shows up as a band a short distance from the weld bead.
Welding pushes the heat-affected zone through that temperature range every time, so carbon content decides how much damage it does:
316 (up to 0.08% C): there's more carbon available to form carbides. Thin sections that cool quickly usually hold up, but heavy sections, multi-pass welds and slow cooling raise the risk.
316L (0.03% C max): there's so little carbon that very few carbides form during normal welding. The chromium stays where it belongs, and the weld zone keeps its corrosion resistance without post-weld annealing.
That's why 316L is the default for welded tanks, piping, food and pharmaceutical equipment, and marine fabrication.
Keep in mind that low carbon helps with short exposures like welding. It isn't designed for parts that sit in the sensitization range for months or years. For sustained high-temperature service, look at 316H or a stabilized grade such as 321 or 347.
Strength and mechanical properties
Carbon adds a little strength, so 316 has slightly higher minimum strength on paper. These are ASTM A240 minimums for annealed material:
Tensile strength: 316 is 75 ksi (515 MPa) min. 316L is 70 ksi (485 MPa) min.
Yield strength (0.2% offset): 316 is 30 ksi (205 MPa) min. 316L is 25 ksi (170 MPa) min.
Elongation in 2 in.: 40% min for both.
Hardness: 95 HRB / 217 HB max for both.
Density: 0.29 lb/in³ (8.0 g/cm³) for both.
In practice, the gap is smaller than the table suggests. Real mill test values usually come in well above these minimums for both grades, and most 316L sold today meets the 316 numbers anyway (see dual certification below). The difference only matters when an engineer has designed to a specific minimum yield, or when a drawing calls out straight 316.
Both grades are non-magnetic when annealed. Cold working, such as bending, drawing or heavy machining, can make either one slightly magnetic. That's normal, and it doesn't mean the material is the wrong grade.
Corrosion resistance, machining and cost
Corrosion resistance. In unwelded parts, 316 and 316L perform essentially the same. Both have the same chromium, nickel and molybdenum, so they handle chlorides, acids and outdoor exposure equally well. The difference shows up in welded parts: 316L keeps its corrosion resistance in the heat-affected zone, while 316 can lose some of it there.
Machining. Both machine about the same. Like other austenitic stainless steels, they're gummy and work-harden quickly. Use sharp tooling, rigid setups and a steady feed, and don't let the tool dwell or rub. If you're doing high-volume machining and don't need the extra corrosion resistance, a free-machining grade like 303 is much easier on tools.
Cost and availability. Prices are usually close, often identical. Most mills now melt 316 to the lower carbon limit and certify it as both grades. So in most cases you're choosing a spec on a drawing, not two different price levels.
Get Instant Pricing on 316 Stainless Steel
What "316/316L dual certified" means
On a mill test report, "316/316L" means the heat meets the requirements of both grades at once:
Carbon is at or below 0.03%, which satisfies 316L.
Strength meets the 316 minimums of 75 ksi tensile and 30 ksi yield. Mills usually get there with a controlled nitrogen addition, which restores the strength the lower carbon gives up.
So one bar can go on a job that calls for 316 or a job that calls for 316L. That's why dual-certified material is the most common form on the market. For most buyers, it settles the question: you get 316L's weldability and 316's strength in the same piece.
When it matters, ask for the mill test report (MTR) and check it. Code work, pressure equipment and regulated industries often need traceable certs.
Which one should you use?
Choose 316L for:
Welded tanks, piping, frames and brackets. It resists weld decay without a post-weld anneal.
Food, beverage, dairy and pharmaceutical equipment. These parts are welded, washed down often and cleaned with harsh chemicals.
Boat hardware, docks and coastal fabrication. They face salt exposure and are usually welded.
Chemical processing and wastewater. The parts go into corrosive service after fabrication.
Choose 316 (or 316/316L) for:
Machined parts that won't be welded, like shafts, fittings and fasteners. With no welding, the extra carbon doesn't hurt.
Parts designed to a 30 ksi minimum yield. 316 meets the higher strength minimum.
Choose something else for:
Long-term service at high temperature. Use 316H, which has higher carbon and holds strength better under heat. Don't use 316L here.
Not sure?
Go with 316/316L dual certified. It covers both specs.
One rule of thumb covers most of this: if it gets welded, buy 316L or dual-certified material. If a drawing specifically calls out straight 316, dual-certified material will still meet it. Just confirm with whoever owns the drawing if there's any doubt.
Buy 316 and 316L stainless at MetalNow
MetalNow carries 316/316L stainless in [bar, sheet and plate — confirm forms]. Pricing is online, there's no minimum order, and every piece is cut to the size you need and shipped nationwide. That makes it easy to get one piece for a prototype or enough for a full production run, without waiting on a quote.
Not sure which grade your job needs? Reply to any MetalNow email or contact our team. We've been in metal distribution for 25 years, and we're glad to help.
Specs are typical ASTM A240 values for annealed plate, sheet and strip. Bar is covered by ASTM A276 and A479, and its minimums can differ. Always confirm requirements against the mill test report and your design spec.