What are the differences between ASTM 304 and ASTM 316?
Dec 17, 2025
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What are the differences between ASTM 304 and ASTM 316?
What are the differences between ASTM 304 and ASTM 316?
The main difference between ASTM 304 and 316 stainless steel lies in their chemical composition, specifically the addition of molybdenum to 316 stainless steel. This makes 316 stainless steel more resistant to chlorides, pitting, and corrosion, making it ideal for marine/coastal and chemical environments. 304 stainless steel, on the other hand, is a general-purpose stainless steel suitable for most common applications where high corrosion resistance is not required. Due to its superior performance, 316 stainless steel is also more expensive.
What are the disadvantages of 304 stainless steel?
One disadvantage of 304 stainless steel is its susceptibility to pitting corrosion, or localized corrosion, especially when exposed to high concentrations of chloride solutions or saltwater environments. Even chloride concentrations as low as 25 ppm can lead to pitting corrosion.
What is 304 stainless steel?
304 stainless steel (EN 1.4301/X5CrNi18-10), also known as 18/8 stainless steel (referring to its chromium and nickel content), is the industry standard for general-purpose stainless steel applications due to its excellent corrosion resistance, ease of processing, and cost-effectiveness.
What is 316 stainless steel?
316 stainless steel (EN 1.4401/X5CrNiMo17-12-2) is similar to 304 stainless steel but contains molybdenum (Mo)-an alloying element that enhances its resistance to corrosion from chlorides, acids, and saltwater.
Chemical Composition of 304 vs 316 Stainless Steel
The main difference in composition between 304 stainless steel and 316 stainless steel lies in the content of nickel and molybdenum. 316 stainless steel contains more nickel and has added molybdenum, which gives it superior corrosion resistance, especially in chloride environments and harsh conditions.
| Element | 304 (Wt. %) | 316 (Wt. %) |
| Iron, Fe | Balance | Balance |
| Chromium, Cr | 18.0 – 20.0 | 16.0 – 18.0 |
| Nickel, Ni | 8.0 – 10.5 | 10.0 – 14.0 |
| Molybdenum, Mo | – | 2.0 – 3.0 |
| Manganese, Mn | ≤ 2.0 | ≤ 2.0 |
| Carbon, C | ≤ 0.08 | ≤ 0.08 |
| Silicon, Si | ≤ 1.0 | ≤ 1.0 |
| Phosphorus, P | ≤ 0.045 | ≤ 0.045 |
| Sulfur, S | ≤ 0.03 | ≤ 0.03 |
Standards for stainless steel 304 and 316 products
| Pipes | Tubes |
|---|---|
| ASTM A312 TP304 | SA 213 TP304 |
| ASTM A312 TP304L | SA 213 TP304L |
| ASTM A312 TP316 | SA 213 TP316 |
| ASTM A312 TP316L | SA 213 TP316L |
| ASTM A312 TP321 | SA 213 TP321 |
ASTM standards define 304 and 316 stainless steel based on their chemical composition, primarily including chromium, nickel, and the key differentiating element molybdenum (316 stainless steel contains molybdenum). Common standards include ASTM A240 (plates/sheets), A276 (bars/profiles), A312 (pipes), and A269 (tubing). 304 stainless steel is a general-purpose stainless steel, while 316 stainless steel, due to its molybdenum content, offers superior corrosion resistance, especially in chloride environments.
Main ASTM standards for 304 and 316 stainless steel, categorized by product type
Plates, Sheets, & Coils: ASTM A240/A240M (covers both 304/304L & 316/316L).
Bars & Shapes: ASTM A276 (for general requirements).
Pipes (Seamless & Welded): ASTM A312/A312M (TP304, TP316).
Tubing (General Purpose): ASTM A269 (covers 304/304L & 316/316L).
Bolts/Fasteners: Often tied to A193/A194 for high temp, but rely on material specs like F593 (304/316).
Comparison table of mechanical properties between 304 stainless steel and 316 stainless steel:
| Property | Stainless Steel 304 | Stainless Steel 316 |
|---|---|---|
| Tensile Strength (MPa, min) | 515 | 515 |
| Yield Strength (0.2% Offset, MPa, min) | 205 | 205 |
| Elongation (% in 50 mm, min) | 40 | 40 |
| Hardness (Rockwell B, max) | 92 HRB | 95 HRB |
| Hardness (Brinell, max) | 201 HB | 217 HB |
| Modulus of Elasticity (GPa) | 193 | 193 |
| Density (g/cm³) | 8.00 | 8.00 |
| Melting Range (°C) | 1400 – 1450 | 1375 – 1400 |
| Primary Corrosion Resistance | Good general corrosion resistance, poor in chlorides | Excellent corrosion resistance, especially to chlorides and acids |
| Typical Max Service Temperature (Continuous) | 870°C | 870°C |
| Impact Strength (Charpy V-Notch, J) | ≥ 100 | ≥ 100 |
Key Points Summary:
304: Standard austenitic stainless steel, with good corrosion resistance (containing 18% chromium and 8% nickel).
316: Due to the addition of 2-3% molybdenum, it has stronger corrosion resistance and is more suitable for marine/chloride environments (containing 16% chromium, 10% nickel, and molybdenum).
Why choose Gnee as your stainless steel supplier?
✅ Over 18 years of export experience, with products sold to more than 80 countries
✅ ISO, SGS, and BV certified
✅ Ample global stock of 304, 316, 316L, and 321 alloy pipes, plates, and bars
✅ Customized processing services available, including cutting, polishing, CNC machining, and packaging
✅ Fast delivery in 7-15 days, supported by global logistics partners
📦 Packaging and Shipping
All stainless steel products are packaged as follows:
Wooden pallets or wooden crates
Moisture-proof packaging
Labeled with heat number, standard, and dimensions
Shipped worldwide via sea, air, or express delivery
Gnee Steel is a supplier of ASTM A213 stainless steel 304, offering a wide range of products including: Pipes: Seamless pipes: Sizes: 4 - 219 mm; Thickness: 0.5 - 20 mm; Welded pipes: Sizes: 5.0 - 1219.2 mm; Thickness: 0.5 - 20 mm; Plates: Plate thickness 0.1 to 100 mm; Plate width 10-2500 mm; Strips; Alloy round bars: Diameter 3-800 mm; Flat bars: Thickness 2-100 mm; Width: 10-500 mm; Hexagonal bars: 2-100 mm; Wires and extruded profiles. We collaborate with steel mills to provide our customers with 304 stainless steel, whose products meet or exceed numerous leading industry standards, including ASTM, ASME, SAE, AMS, ISO, DIN, EN, and BS standards.
Gnee Steel stocks and sells ASTM A213 stainless steel 304, pipes, tubes, plates, strips, sheets, round bars, flat bars, forged billets, hexagonal steel, wires, and extruded profiles. Please feel free to contact us via email at sales@gneestainless.com for a quote.
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