316 stainless steel plate and 316L stainless steel plate are chromium-nickel-molybdenum austenitic stainless steel flat products supplied as plate, sheet and coil. The molybdenum addition improves resistance to localized corrosion, particularly pitting and crevice attack in chloride-containing and other compatible corrosive environments. These grades are used for process equipment, tanks, heat-exchanger components, water-treatment equipment and fabricated parts where the corrosion environment requires more resistance than standard Cr-Ni stainless steel.
Grade 316 corresponds to UNS S31600, while 316L corresponds to UNS S31603. Both grades contain molybdenum, but 316L has a lower carbon limit. As a result, 316L stainless steel plate is commonly selected for welded fabrication where resistance to sensitization and intergranular corrosion in the heat-affected region is important.
316/316L Grades, Specifications and Supply Range
316 and 316L are available in hot-rolled and cold-rolled flat-product forms. Product form is selected according to thickness, surface condition and downstream fabrication. Hot-rolled material is normally used for thicker plate, while cold-rolled sheet and coil provide thinner gauges and more controlled surface finishes.
The existing OCTAL Metals supply range covers plate, sheet and coil from thin cold-rolled material through heavier hot-rolled plate. Cutting can also be coordinated according to the required thickness, part geometry and edge condition.
| Supply Item | Available Range |
|---|---|
| Grades | 316 / 316L |
| UNS Designations | S31600 / S31603 |
| Standards | ASTM A240 / ASME SA240 |
| Product Forms | Plate, sheet and coil |
| Cold-Rolled Thickness | 0.02–4 mm |
| Hot-Rolled Plate Thickness | 4.5–100 mm |
| Width | 900–2400 mm |
| Plate Length | 3000–12000 mm |
| Surface Conditions | Natural, 2B, Mirror |
| Cutting | Laser, waterjet and plasma cutting |
An ASTM A240 316 stainless steel plate order therefore needs more than a grade designation. Thickness, width, length, finish and any additional processing requirements define the actual delivered product. ASTM A240/A240M applies to stainless steel plate, sheet and strip and includes chemical-composition and mechanical-property requirements.
316 vs 316L and Material Properties
316 and 316L use the same basic chromium-nickel-molybdenum alloy system. Their main distinction is carbon content. Standard 316 allows a higher maximum carbon level, while 316L limits carbon to approximately 0.03% maximum. The lower carbon content reduces carbide precipitation caused by welding heat and improves resistance to intergranular corrosion after welding.
This difference is most relevant in welded or thermally affected components. It does not mean that 316L has substantially higher pitting resistance than 316 simply because the carbon level is lower. Pitting and crevice resistance are controlled mainly by alloying elements such as chromium, molybdenum and nitrogen, together with the actual exposure conditions.
| Element (%) | 316 (S31600) | 316L (S31603) |
|---|---|---|
| Carbon, Max | 0.08 | 0.030 |
| Manganese, Max | 2.00 | 2.00 |
| Phosphorus, Max | 0.045 | 0.045 |
| Sulphur, Max | 0.030 | 0.030 |
| Silicon, Max | 0.75 | 0.75 |
| Chromium | 16.0–18.0 | 16.0–18.0 |
| Nickel | 10.0–14.0 | 10.0–14.0 |
| Molybdenum | 2.0–3.0 | 2.0–3.0 |
Both grades contain 2.0–3.0% molybdenum, which contributes to their resistance to pitting and crevice corrosion. The main difference is carbon content: 316L limits carbon to 0.030% maximum, reducing sensitization risk in welded or thermally affected components.
Mechanical Properties of 316 and 316L Stainless Steel
| Mechanical Property | 316 (S31600) | 316L (S31603) |
|---|---|---|
| Tensile Strength, Min | 75 ksi (515 MPa) | 70 ksi (485 MPa) |
| Yield Strength, Min, 0.2% Offset | 30 ksi (205 MPa) | 25 ksi (170 MPa) |
| Elongation, Min | 40% | 40% |
316 and 316L have similar overall mechanical behavior, although 316L has slightly lower specified minimum tensile and yield strengths. Both grades retain high elongation for forming and fabrication. The required mechanical properties should be confirmed according to the ordered thickness, product form and applicable specification.
Why Molybdenum Matters in 316/316L Stainless Steel
The main alloying difference between 316/316L and conventional 304/304L is the addition of molybdenum. The current 316/316L product data lists approximately 2.0–3.0% Mo together with chromium and nickel. Molybdenum strengthens the alloy’s resistance to localized breakdown of the passive surface film and is especially important for pitting and crevice-corrosion resistance.
Pitting usually develops as small localized cavities after the passive film is damaged, while crevice corrosion develops in restricted areas such as gasket interfaces, deposits, lap joints or narrow gaps. Resistance to these forms of corrosion increases as chromium, molybdenum and nitrogen content increases. However, material grade alone does not define the final corrosion behavior. Chloride concentration, temperature, pH, deposits, surface finish and crevice geometry also influence whether localized corrosion develops.
| Material Factor | 304/304L | 316/316L |
|---|---|---|
| Alloy System | Cr-Ni austenitic | Cr-Ni-Mo austenitic |
| Molybdenum | No intentional Mo addition | Approximately 2–3% |
| Main Corrosion Difference | General corrosion service | Improved pitting and crevice resistance |
| Typical Selection Driver | Mild-to-moderate environment | Greater localized-corrosion risk |
The addition of molybdenum does not make 316/316L immune to chloride corrosion. High chloride levels, elevated temperature or unfavorable crevice conditions can exceed the practical service range of 316/316L and require a different alloy system.
Difference between 316 and 316L
The primary difference between 316 and 316L stainless steels lies in their carbon content and how this affects their properties:
Carbon Content:
- 316 stainless steel typically has a carbon content of up to 0.08%.
- 316L stainless steel has a lower carbon content, capped at 0.03%. This reduction in carbon enhances its corrosion resistance.
Corrosion Resistance:
- Both grades offer excellent resistance to corrosion, particularly in chloride environments. However, 316L’s lower carbon content makes it slightly more resistant to corrosion, especially in welded areas where carbon could increase susceptibility to corrosion.
Welding and Fabrication:
- 316L is often preferred for welding applications because it minimizes the risk of carbide precipitation during the welding process, which can occur in higher carbon grades like 316. This makes 316L more suitable for projects that involve extensive welding.
Applications of 316/316L Stainless Steel by Service Condition
Chemical and Process Equipment
316/316L plate and sheet are used for tanks, fabricated vessels, valves, flanges and other process-equipment components where the operating medium creates greater corrosion demand than a standard Cr-Ni stainless steel can provide. The actual selection depends on chemical concentration, temperature, weld condition and whether stagnant or crevice areas are present.
Heat Exchanger and Cooling-Water Components
Heat exchangers and cooling systems combine temperature, liquid chemistry and restricted flow passages. In these applications, the molybdenum content of 316/316L provides improved resistance to localized corrosion. However, chloride concentration, deposits and crevice geometry remain important because they can create severe conditions at tube sheets, joints and other confined areas.
Coastal and Marine-Atmosphere Fabrication
316/316L can be used in many coastal and moderately aggressive atmospheric environments because the molybdenum addition improves resistance to chloride-related surface attack. Continuous seawater immersion or aggressive marine splash exposure is different from ordinary coastal atmosphere, however, and may require a higher-alloyed stainless grade depending on temperature and chloride loading.
Food, Pharmaceutical and Cleanable Equipment
316 stainless steel sheet and 316L sheet are also used for fabricated equipment in food, beverage, pharmaceutical and other cleanable process environments. In these applications, the alloy grade works together with surface finish, weld condition and cleaning chemistry. A smooth and properly restored surface is therefore part of the finished material system rather than only an appearance requirement.
316 Stainless Steel Plate
Difference between 304 and 316 Stainless Steel
The main differences between 304 and 316 stainless steels relate to their chemical composition, properties, and applications:
Chemical Composition:
- 304 Stainless Steel: This grade typically contains 18% chromium and 8% nickel. It does not have molybdenum.
- 316 Stainless Steel: This grade contains 16% chromium, 10% nickel, and 2-3% molybdenum, which is added to enhance corrosion resistance.
Corrosion Resistance:
- 304: While 304 stainless steel offers good corrosion resistance in many environments, it is more susceptible to corrosion, particularly in chloride environments.
- 316: The addition of molybdenum in 316 improves its resistance to pitting and crevice corrosion, making it more suitable for marine and harsh environments.
Mechanical Properties:
- Both 304 and 316 exhibit similar mechanical properties, including strength and toughness. However, 316 typically performs better under chemical exposure due to its enhanced composition.
Applications:
- 304: Commonly used in kitchen equipment, food processing, and general structural applications.
- 316: Frequently used in marine applications, chemical processing, and medical devices due to its superior corrosion resistance.
304, 304L Stainless Steel Plate
Manufacturing Methods for 316/316L Stainless Steel Plate
The manufacturing methods for 316 and 316L stainless steel plates typically include several key processes designed to ensure the material’s properties are preserved:
1. Melting and Alloying:
- The production begins with melting raw materials, including iron, chromium, nickel, and molybdenum, in a furnace. The mix is carefully controlled to maintain the desired chemical composition for 316/316L stainless steel.
2. Casting:
- After melting, the molten metal is cast into slabs or ingots. This can be done through processes like continuous casting or ingot casting. Continuous casting is often preferred for its efficiency and consistent quality of the resulting slabs.
3. Hot Rolling:
- The solidified slabs are then subjected to hot rolling, where they are heated to a specific temperature and passed through rollers to achieve the desired thickness. This process imparts strength and durability while enhancing the grain structure of the stainless steel.
4. Cold Rolling:
- For specific applications requiring finer tolerances and surface finishes, the hot-rolled plates can undergo cold rolling. This process is performed at room temperature and further refines the thickness and finish of the plates.
5. Annealing:
- Following the rolling processes, the stainless steel plates are often annealed. This heat treatment relieves internal stresses, improves ductility, and enhances corrosion resistance, particularly important for 316 and 316L grades.
6. Pickling and Passivation:
- After annealing, the plates may undergo pickling, which removes oxide scales, followed by passivation. Passivation enhances the chromium oxide layer on the surface, improving corrosion resistance.
7. Cutting and Finishing:
- Finally, the stainless steel plates are cut to the required dimensions and may undergo additional finishing processes, such as polishing, to achieve the desired surface quality.
Hot Rolling
Hot rolling is used for 316/316L stainless steel plate and heavier flat products. It supports larger thicknesses and subsequent cutting, welding or machining. The current hot-rolled supply range covers approximately 4.5–100 mm thickness.
Cold Rolling
Cold rolling is used for thinner 316 stainless steel sheet and 316 stainless steel coil, providing closer thickness control and a smoother surface for forming and fabrication. The current cold-rolled supply range covers approximately 0.02–4 mm thickness.
Heat Treatment
In order to ensure that the mechanical properties such as yield strength, tensile strength, elongation and hardness of all kinds of stainless steel plates meet the requirements, the steel plate must be subjected to heat treatment such as annealing, solution treatment and aging treatment before delivery.
316N, 316LN
After normalization, 316 or 316L becomes 316N or 316LN, respectively, resulting in improved yield strength of at least 320 MPa for thicknesses greater than 38 mm.
For thicknesses below 38 mm, the minimum yield strength for 316N is 550 MPa, with a tensile strength of 240 MPa. In comparison, 316LN has a minimum yield strength of 515 MPa and a tensile strength of 205 MPa.
Weight of 316 Stainless Steel Plate, Sheet, Coil
To calculate the weight of 314 stainless steel plate in kgs use the formula: length (m) x width (m) x thickness (mm) x 7.93
Inspection, Supply and Ordering Requirements
316/316L material identification begins with the specified grade and applicable material standard. Chemical composition is particularly important because chromium, nickel and molybdenum distinguish the alloy from lower-alloyed stainless grades, while carbon content differentiates 316 from 316L. ASTM A240/A240M also specifies applicable mechanical-property requirements for stainless steel plate, sheet and strip.
Delivery inspection can include verification of dimensions, surface condition, markings and the material certificate against the ordered heat or lot. Where PMI or third-party inspection is required, it should be identified in the purchase specification before material processing so that the inspection scope can be coordinated.
As a 316 stainless steel plate supplier, OCTAL Metals supplies 316 and 316L plate, sheet and coil together with cut-to-size processing. Available cutting methods include laser, waterjet and plasma cutting, while thickness, width, length and surface condition are selected from the confirmed supply range.
FAQ
Q1: Does the lower carbon content of 316L improve chloride pitting resistance?
A1: Not significantly by itself. 316 and 316L have similar chromium, nickel and molybdenum ranges, so their pitting resistance is broadly comparable. The lower carbon content of 316L mainly reduces sensitization and intergranular-corrosion risk after welding.
Q2: Is 316/316L stainless steel suitable for continuous seawater service?
A2: Not automatically. Pitting and crevice corrosion can still occur in seawater. Chloride level, temperature, deposits and crevice geometry must be evaluated, and more highly alloyed stainless steels may be required for severe service.
Q3: Why should weld heat tint be removed from 316L stainless steel?
A3: Weld heat tint and oxide can reduce local corrosion resistance. Suitable post-weld cleaning removes the affected oxide and contamination and helps restore a more uniform corrosion-resistant surface.
Q4: Does ASTM A240 mean 316 stainless steel is suitable for any chloride environment?
A4: No. ASTM A240 defines requirements for stainless steel plate, sheet and strip, including chemistry and mechanical properties. Suitability for a specific chloride concentration, temperature or crevice condition must be evaluated separately.