What are the differences between Inconel 718 and 316 SS?
What are the differences between Inconel 718 and 316 SS?
The main differences between Inconel 718 and 316 stainless steel lie in their composition, high-temperature strength, and cost. Inconel 718 is a nickel-based alloy with excellent high-temperature strength and corrosion resistance, making it suitable for extreme environments such as jet engines; while 316 stainless steel is a more economical iron-based stainless steel that performs well in moderate-temperature and corrosive environments.
Why is Inconel 718 difficult to machine?
Inconel 718 nickel-based superalloys exhibit excellent properties at high temperatures, making them widely used in the aerospace, marine, and automotive industries. However, Inconel 718 has poor thermal conductivity and is prone to rapid strain hardening, resulting in poor machinability and poor surface finish.
Inconel 718 offers significantly higher strength at high temperatures and excellent creep resistance, but it is also more expensive, making it ideal for aerospace and high-stress applications. In contrast, stainless steel 316 is more economical and suitable for applications requiring good strength and corrosion resistance but not extreme temperatures or stress. The choice between the two depends primarily on specific requirements for temperature, strength, and cost.
Comparison: Inconel 718 vs. 316 Stainless Steel
| Feature | Inconel 718 | 316 Stainless Steel |
|---|---|---|
| Base Material | Nickel-based alloy | Iron-based alloy (stainless steel) |
| Key Application | High-temperature, high-stress environments like jet engines, gas turbines, and rocket engines | General industrial use, marine applications, food processing, and surgical implants |
| High-Temperature Strength | Exceptional strength up to 700°C (1292°F) | Lower strength at high temperatures compared to Inconel 718 |
| Corrosion/Oxidation Resistance | Excellent resistance | Good resistance, especially marine resistance due to molybdenum |
| Cost | More expensive | More economical |
| Weldability | Requires specific heat treatments and care due to potential for cracking in the heat-affected zone | Relatively easier to weld |
SS 316 Composition
| Grade | C | Mn | Si | P | S | Cr | Mo | Ni | N |
|---|---|---|---|---|---|---|---|---|---|
| SS 316 | 0.08 max | 2 max | 0.75 max | 0.045 max | 0.030 max | 16 – 18 | 2 – 3 | 10 – 14 | 0.1 max |
SS 316 Melting Point, Density and Tensile Strength
| Grade | Density | Melting Point | Tensile Strength | Yield Strength (0.2%Offset) | Elongation |
| SS 316 | 8.0 g/cm3 | 1454 °C (2650 °F) | Psi – 75000 , MPa – 515 | Psi – 30000 , MPa – 205 | 35 % |
Inconel Composition
| Inconel | Element (% by mass) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Ni | Cr | Fe | Mo | Nb | Co | Mn | Cu | Al | Ti | Si | C | S | P | B | |
| 718 | 50.0–55.0 | 17.0–21.0 | balance | 2.8–3.3 | 4.75–5.5 | 1.0 | 0.35 | 0.2–0.8 | 0.65–1.15 | 0.3 | 0.35 | 0.08 | 0.015 | 0.015 | 0.006 |
Inconel Melting Point, Density and Tensile Strength
| Density | Melting Point | Tensile Strength | Yield Strength (0.2%Offset) | Elongation | |
|---|---|---|---|---|---|
| 718 | 8.2 g/cm3 | 1350 °C (2460 °F) | Psi – 135,000 , MPa – 930 | Psi – 70,000 , MPa – 482 | 45 % |
Why Choose Gnee Nickel Alloy (Supplier Example)?
✅ Large stock of Inconel alloy tubes/bars/plates/fittings/coils, fast shipping.
✅ Factory direct sales, highly competitive prices, excellent value for money.
✅ Comprehensive quality assurance: Material Testing Certificate (MTC), chemical composition certificate, and mechanical property certificate.
✅ Value-added services: slitting, cutting, polishing, surface treatment.
✅ Worldwide shipping, secure and reliable packaging, and provision of export-required documents.
Email: ss@gneemetal.com
Gnee Steel is a supplier of Inconel 718 alloy, offering a wide range of products including: seamless pipe (sizes: 4-219 mm; thickness: 0.5-20 mm); welded pipe (sizes: 5.0-1219.2 mm; thickness: 0.5-20 mm); plates (thickness: 0.1 to 100 mm; width: 10-2500 mm); strips; alloy round bars (diameter: 3-800 mm); flat bars (thickness: 2-100 mm; width: 10-500 mm); hexagonal bars (size: 2-100 mm); wire rods; and extruded profiles. We collaborate with steel mills to provide our customers with Inconel 718 alloy products that meet or exceed numerous leading industry standards, including ASTM, ASME, SAE, AMS, ISO, DIN, EN, and BS standards.
Gnee Steel stocks and sells Inconel 718, pipes, plates, strips, round bars, flat bars, forged billets, hexagonal steel, wire rods, and extruded profiles. Please feel free to contact us at ss@gneesteel.com for a quote.
