Comparison of 316L and 316H Stainless Steel: Low-Carbon Corrosion-Resistant vs High-Carbon High-Temperature Grade
Dec 25, 2025
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Grade Designations and Standards
316L and 316H are molybdenum-bearing austenitic stainless steels with the same nominal 17-12-2 base of chromium, nickel and molybdenum. They differ in carbon content, and this single difference governs their behaviour during welding and at elevated temperature. Plate is specified to ASTM A240, seamless boiler and superheater tube to ASTM A213, and pipe to ASTM A312.
| Grade | UNS | EN 10088 | JIS |
|---|---|---|---|
| 316L | S31603 | 1.4404 | SUS316L |
| 316H | S31609 | No direct equivalent | SUS316H |
316L is the low-carbon grade with a maximum of 0.03% carbon. 316H retains 0.04–0.10% carbon, which raises strength at high temperature. Because no EN 10088 designation exists for 316H, it is normally ordered by ASTM designation and UNS number.
Chemical Composition and Mechanical Properties
| Element | 316L (S31603) | 316H (S31609) |
|---|---|---|
| C | ≤0.03 | 0.04–0.10 |
| Cr | 16.0–18.0 | 16.0–18.0 |
| Ni | 10.0–14.0 | 10.0–14.0 |
| Mo | 2.00–3.00 | 2.00–3.00 |
| Mn | ≤2.00 | ≤2.00 |
| Si | ≤0.75 | ≤0.75 |
| P | ≤0.045 | ≤0.045 |
| S | ≤0.030 | ≤0.030 |
| Property | 316L | 316H |
|---|---|---|
| Tensile strength, MPa | 485 | 515 |
| Yield strength, MPa | 170 | 205 |
| Elongation in 2 in, % | 40 | 40 |
Corrosion Resistance and Weldability
In the annealed condition both grades offer the same general and pitting corrosion resistance because the chromium, nickel and molybdenum contents are identical. The difference appears at the weld. The low carbon of 316L suppresses chromium carbide precipitation in the heat-affected zone, so 316L keeps full corrosion resistance after welding without post-weld heat treatment. The higher carbon of 316H can sensitise when the weld area is held in the 425–850°C range, leaving chromium-depleted grain boundaries. For welded vessels, tanks and piping in chloride-bearing media, 316L is therefore the correct choice.
High-Temperature Behaviour and Applications
Above roughly 500°C the design of austenitic components is controlled by creep strength rather than room-temperature properties. The higher carbon content of 316H raises its elevated-temperature strength, so it is the grade normally specified for superheater tubes, reheater tubes, headers and other pressure parts in boilers and heat recovery systems. 316L is selected where corrosion resistance and weldability dominate: chemical storage tanks, food and beverage plant, pharmaceutical equipment, and marine components.
How to Choose
Base the decision on design temperature and welding. A welded component operating at low to moderate temperature in a corrosive medium should be 316L. A component operating continuously above about 500°C, where strength at temperature governs, should be 316H, with the design code confirmed. If a welded part is also exposed to high temperature, review whether a stabilized grade is required by the design specification.
Frequently Asked Questions
Q1. What does the L in 316L mean?
Low carbon, with a maximum of 0.03%, which prevents carbide precipitation during welding.
Q2. What does the H in 316H mean?
High carbon, controlled at 0.04–0.10%, which increases strength at elevated temperature.
Q3. Do 316L and 316H have the same corrosion resistance?
Yes in the annealed condition. After welding, 316L retains its resistance while 316H can sensitise unless solution annealed.
Q4. Which grade should I specify for a welded chemical storage tank?
316L, because its low carbon keeps the weld zone resistant without post-weld heat treatment.
Q5. Which grade is used for superheater tubing?
316H, because its higher carbon gives better creep strength above roughly 500°C.
Q6. Are 316L and 316H interchangeable?
No. The design code and operating temperature determine the required grade, and substituting one for the other can change both weldability and high-temperature life.
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