What are the differences between Inconel 600 330 and 625 alloys?
Gnee Steel
What are the differences between Inconel 600 330 and 625 alloys?
The main differences between Inconel 600, 330, and 625 alloys lie in their chemical composition, resulting in different properties and ideal applications. Inconel 600 has the highest nickel content, making it best suited for high-temperature applications but not for strong oxidizing acids. Inconel 330 withstands high-temperature oxidizing sulfide environments well, while Inconel 625 has a more balanced composition with the addition of molybdenum and niobium, giving it superior corrosion resistance (withstanding a wider range of acids), higher high-temperature strength, and good weldability.
Gnee Steel
What are the differences between Inconel 600 and 625?
Both alloys offer excellent performance, but Inconel 625 provides better corrosion resistance, oxidation resistance, and weldability. However, Inconel 600 performs well at high temperatures and is less expensive.
Inconel 600 Alloy
Inconel 600 is a commonly used high-temperature oxidation-resistant alloy. Its nickel content is at least 72%, more than twice that of Incoloy 330.
While the high nickel content improves the alloy's high-temperature oxidation resistance and carburization resistance, it also makes it more susceptible to sulfur corrosion. As stated in the Rolled Alloys Guide, Inconel 600® is not suitable for oxidation, reduction, or corrosion by molten metals such as copper, zinc, or magnesium. However, it exhibits good tensile strength, above-average oxidation and thermal shock resistance, and excellent carburization resistance. With stress-relief treatment, it also has excellent resistance to chloride stress corrosion cracking.
Chemical analysis
| % | Ni+Co | Cr | Cu | C | Mn | Si | S | Fe |
|---|---|---|---|---|---|---|---|---|
| Min | 72 | 14 | 0 | 0 | 0 | 0 | 0 | 6 |
| Max | - | 17 | 0.5 | 0.15 | 1 | 0.5 | 0.015 | 10 |
ALLOY 600 MECHANICAL PHYSICAL PROPERTIES
| Property | 21°C | 538°C | 649°C | 760°C | 871°C | 982°C | 1093°C |
| Ultimate Tensile Strength /MPa | 641.2 | 579.2 | 448.2 | 189.6 | 103.4 | 51.7 | - |
| 0.2% Yield Strength /MPa | 255.1 | 196.5 | 182.7 | 117.2 | 62 | 27.6 | - |
| Charpy Impact V-notch /J | 61 | 63.7 | 52.9 | 62.4 | 108.5 | 160 | - |
| Coefficient of Thermal Expansion µm/m⁰C | - | 15.1 | 15.5 | 15.6 | 16.4 | - | 16.7 |
| Thermal Conductivity /kcal/(hr.m.°C) | 12.8 | 19.6 | 21.3 | 19.3 | 23.8 | - | - |
| Modulus of Elasticity / x105 MPa | 2.1 | 1.77 | 1.69 | 1.63 | 1.53 | - | 1.4 |
Inconel 625 Alloy
Inconel 625 has a nickel content between Inconel 330 and Inconel 600, at 58%. What is the most abundant element after nickel? It's chromium, at 20-23%. The addition of molybdenum and niobium ensures optimal performance at various temperatures. It is known to possess excellent strength and toughness over a temperature range of -32°F (0°C) to 2000°F (1093°C).
This alloy exhibits good fatigue resistance, high creep rupture strength, and resistance to crevice corrosion. It is also easier to weld compared to other known Inconel alloys. Some applications of Inconel 625 include chemical plant equipment, seawater equipment, and engine exhaust systems. It exhibits high resistance to oxalic acid corrosion compared to other metals. They are subjected to 6.0 mils/year of oxalic acid solution corrosion. In comparison, other steels are subjected to 44.6 mils/year of corrosion in similar solutions. However, the corrosive effect of 10% sulfuric acid is not so significant.
| % | Cr | Ni | Mo | Co | Nb+Ta | Al | Ti | C | Fe | Mn | Si | P | S |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Min | 20 | - | 8 | - | 3.15 | - | - | - | - | - | - | - | - |
| Max | 23 | Balance | 10 | 1 | 4.15 | 0.4 | 0.4 | 0.1 | 5.0 | 0.5 | 0.5 | 0.015 | 0.015 |
ALLOY 625 MECHANICAL PHYSICAL PROPERTIES
| Property | 21°C | 204 °C | 316 °C | 427 °C | 538 °C | 649 °C | 760 °C | 871 °C |
| Ultimate Tensile Strength /Mpa | 992.9 | 923.9 | 910.1 | 910.1 | 896.3 | 820.5 | 537.8 | 275.8 |
| 0.2% Yield Strength /MPa | 579.2 | 455.1 | 434.4 | 420.6 | 420.6 | 413.7 | 406.8 | 268.9 |
| Elongation % | 44 | 45 | 42.5 | 45 | 48 | 34 | 59 | 117 |
| Coefficient of Thermal Expansion µm/m⁰C | - | 13.1 | 13.3 | 13.7 | 14 | 14.8 | 15.3 | 15.8 |
| Thermal Conductivity /kcal/(hr.m.°C) | 8.5 | 10.7 | 12.2 | 13.5 | 15 | 16.4 | 17.9 | 19.6 |
| Modulus of Elasticity MPa x 105 | 2.07 | 1.98 | 1.92 | 1.86 | 1.79 | 1.65 | 1.59 | 1.48 |
Incoloy 330 Alloy
Although it's part of Inconel's heat-resistant metal alloy series, the 330 model is more commonly referred to as Incoloy or RA330. Incoloy contains between 34% and 37% nickel and between 17% and 20% chromium, giving it excellent resistance to oxidation at temperatures up to 2,100°F (1,148°C), as well as resistance to carburizing and nitriding.
Rapid temperature changes (common in heat-treatment applications) do not pose a significant problem for alloy 330 due to its good resistance to thermal shock. Like many Inconel alloys, alloy 330 maintains high tensile strength at extreme temperatures compared to ordinary steel alloys.
In fact, in their alloy performance guide, Gnee Steel lists RA330 as having "good" (meaning above average) strength, oxidation resistance, carburization resistance, and sulfur oxide resistance, and its thermal shock resistance is rated as "best" among the high-temperature alloys they offer.
Chemical Composition
The chemical composition of INCOLOY alloy 330 is given in the following table.
| Element | Content (%) |
|---|---|
| Iron, Fe | 43 |
| Nickel, Ni | 34-37 |
| Chromium, Cr | 17-20 |
| Manganese, Mn | ≤2 |
| Others | Remainder |
Physical Properties
The following table discusses the physical properties of INCOLOY alloy 330.
| Properties | Metric | Imperial |
|---|---|---|
| Density | 8.08 gm/cm3 | 0.292 lb/in3 |
Mechanical Properties
The mechanical properties of INCOLOY alloy 330 are tabulated below.
| Properties | Metric | Imperial |
|---|---|---|
| Tensile strength(annealed) | 600 MPa | 87 ksi |
| Yield strength(annealed) | 280 MPa | 40.6 ksi |
| Elongation at Break | 45% | 45% |
Why Choose Gnee Nickel Alloy (Supplier Example)?
✅ Large stock of Incoloy 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 GH4169 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 GH4169 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 GH4169, 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.
