What are the differences between 308 stainless steel and 316 stainless steel?
What are the differences between 308 stainless steel and 316 stainless steel?
The main difference is that 316 stainless steel contains molybdenum, giving it superior corrosion resistance, especially in chloride and seawater environments, making it ideal for marine and chemical applications. 308 stainless steel, on the other hand, does not contain molybdenum, but still offers good general corrosion resistance and strength, and is often used as an economical filler material for welding 304 stainless steel in general manufacturing applications. Compared to 308 stainless steel, 316 stainless steel has slightly lower chromium content and slightly higher nickel content, which enhances its durability under harsh conditions.
Does 308 stainless steel rust?
Characteristics of 308 stainless steel:
It possesses excellent corrosion resistance, especially in chloride environments. Its high tensile strength and durability make it an ideal choice for structural applications.
What is 308 stainless steel?
308 stainless steel is an austenitic chromium-nickel-molybdenum alloy with excellent corrosion resistance. Compared to other stainless steel alloys, it offers superior heat resistance while maintaining high mechanical strength. Its non-magnetic properties make it an ideal choice for the food industry or medical environments. Furthermore, its low carbon content prevents the formation of carbide precipitates during welding, thus improving its usability and long-term performance in almost all applications.
What is 316 stainless steel?
316 stainless steel is an austenitic stainless steel containing chromium, nickel, and molybdenum. It offers excellent corrosion resistance, high-temperature resistance, and resistance to stress corrosion cracking, making it ideal for industrial applications such as chemical storage tanks and heat exchangers. Its ability to withstand extreme temperatures makes it suitable for medical devices or manufacturing processes involving high temperatures.
Chemical composition of stainless steel 308 vs. stainless steel 316
| Element | 308 Stainless Steel (%) | 316 Stainless Steel (%) |
| Carbon (C) | ≤ 0.08 | ≤ 0.08 |
| Chromium (Cr) | 19.0 – 21.5 |
16.0 – 18.0 |
| Iron (Fe) | Balance | Balance |
| Manganese (Mn) | ≤ 2.0 | ≤ 2.0 |
| Molybdenum (Mo) | - | 2.0 – 3.0 |
| Nickel (Ni) | 10.0 – 12.0 | 10.0 – 14.0 |
| Nitrogen (N) | ≤ 0.10 | ≤ 0.10 |
| Phosphorus (P) | ≤ 0.045 | ≤ 0.045 |
| Silicon (Si) | ≤ 0.75 | ≤ 0.75 |
| Sulfur (S) | ≤ 0.03 | ≤ 0.03 |
Mechanical Properties of 308 and 316 Stainless Steel
| Property | 308 Stainless Steel | 316 Stainless Steel |
| Tensile Strength (MPa) | 550 – 750 | 515 – 690 |
| Yield Strength (MPa) | ~210 – 250 | ~205 – 290 |
| Ductility and Toughness | Excellent | Excellent |
| Brinell Hardness (HB) | 160 – 200 | 150 – 217 |
| Fatigue Strength (MPa) | ~240 | ~240 |
| Shear Strength (MPa) | ~290 |
~300 |
| Elastic Modulus (GPa) | ~193 | ~193 |
| Elongation at Break (%) | ≥ 40 | ≥ 40 |
| Poisson's Ratio | 0.30 | 0.30 |
| Area Reduction (%) | ≥ 55 | ≥ 55 |
| Rockwell Hardness (HRB) | 80 – 90 | 79 – 95 |
| Shear Modulus (GPa) | ~77 | ~77 |
| Tensile Strength: UTS (MPa) | 550 – 750 | 515 – 690 |
| Tensile Strength: Yield (MPa) | ~210 – 250 | ~205 – 290 |
Comparison of the thermal properties of 308 stainless steel and 316 stainless steel
| Thermal Property | 308 Stainless Steel | 316 Stainless Steel |
| Latent Heat of Fusion (J/g) | ~260 | ~260 |
| Maximum Temperature – Corrosion (°C) | ~870 | ~925 |
| Maximum Temperature – Mechanical (°C) | ~870 | ~870 |
| Melting Point (Liquidus, °C) | 1400 – 1455 | 1370 – 1400 |
| Melting Point (Solidus, °C) | 1395 – 1440 | 1375 – 1400 |
| Specific Heat (J/kg·K at 20°C) | ~500 | ~500 |
| Thermal Conductivity (W/m·K at 100°C) | ~16.3 | ~16.2 |
| Thermal Conductivity (W/m·K at 500°C) | ~21.5 | ~21.4 |
Key takeaways:
Compared to 308 stainless steel, 316 stainless steel exhibits slightly superior corrosion resistance in high-temperature environments.
Both materials have similar melting point ranges and thermal conductivity, making them suitable for precision CNC machined stainless steel parts operating in thermally stressed environments.
In terms of thermal expansion and heat resistance, 316 stainless steel maintains its structural integrity better in chemically corrosive or high-temperature environments.
Ultimately, for components that need to withstand high temperatures for extended periods-such as marine boilers, food processing heaters, or medical sterilizers-316 stainless steel CNC machined parts often outperform 308 stainless steel parts, especially when manufactured by an experienced CNC machining facility.
308 Stainless Steel vs. 316 Stainless Steel: Comparison Table of Advantages and Disadvantages
| Category | 308 Stainless Steel | 316 Stainless Steel |
| Main Advantage | Cost-effective with good general corrosion resistance | Superior resistance to chloride corrosion and harsh chemicals |
| Corrosion Resistance | Good in mild environments; susceptible to chlorides | Excellent in marine and chemical environments due to molybdenum |
| Weldability | Excellent weldability; 308L resists intergranular corrosion | Also weldable; more sensitive to heat input during fabrication |
| Strength | High tensile and yield strength; durable for structural applications | Very high strength and toughness; holds up in mechanical stress and heat |
| Cost | Lower cost, more economical for general use | Higher initial cost, but offers long-term value in harsh environments |
| Chemical Resistance | Moderate chemical resistance | Excellent resistance to acids, alkalis, and chlorides |
| Temperature Resistance | Good mechanical performance up to ~870°C | Maintains mechanical and corrosion resistance up to ~925°C |
| Ease of Machining | Easier to machine with standard tools | Slightly tougher to machine; requires quality tools and expertise |
| Availability | Readily available for general applications | Available, but may be less stocked in certain regions |
| Drawbacks | Not suitable for chloride-rich or aggressive chemical environments | More expensive; may be over-engineered for standard applications |
| Best Use Cases | General fabrication, structural parts, 308 stainless steel CNC machining parts | Marine, medical, food processing, and chemical applications; 316 CNC machined parts |
Comparison of applications of 308 stainless steel and 316 stainless steel
| Industry | 308 Stainless Steel | 316 Stainless Steel |
| Marine | Light-duty marine hardware, interior brackets, housings (non-exposed environments) | Boat fittings, propeller shafts, underwater fasteners, valves, and components exposed to seawater |
| Chemical Processing | Frames, support structures, non-critical chemical containers | Tanks, pipes, heat exchangers, valves, and processing equipment exposed to corrosive chemicals |
| Building & Construction | Exterior panels, supports, window/door frames (inland environments) | Coastal architectural components, fasteners, curtain walls, bridges, structural elements |
| Food & Beverage | Equipment frames, general-use kitchen components | Mixing vessels, cutting tools, sanitary conveyor systems, food-contact surfaces (FDA compliant) |
| Medical Devices | Rarely used due to limited sterilization durability | Surgical instruments, orthopedic implants, diagnostic tools (autoclave-resistant and biocompatible) |
| Automotive | Exhaust sleeves, mounting brackets, general fasteners | Fuel line components, sensors, exhaust manifolds, parts exposed to salt or chemicals |
Gnee Steel specializes in the production of a wide range of stainless steel products. Gnee Steel's product packaging includes: Steel Strapping: Pipes with an outer diameter of 3 inches or less are typically strapped together with polypropylene film to prevent rust during ocean shipping, and then secured with steel strapping. Wooden Cases/Crates: Pipes are typically packaged in wooden cases or crates to protect the pipes during transportation, especially those that are longer or have larger diameters. Seaworthy Export Packaging: Suppliers typically use standard seaworthy export packaging methods, which may include a variety of materials and techniques to protect the pipes during transportation. Tarpaulin Packaging: This prevents rain, seawater, and other external factors from penetrating the export crates during transportation. Gnee Steel specializes in the production and sale of alloy materials. Gnee Steel's products are widely used in the aerospace, chemical, power, automotive, and nuclear energy sectors, and we can provide customized alloy material solutions based on customer needs. For alloy material pricing or customized alloy material solutions, please contact us for a quote: ru@gneesteelgroup.com