Alloy 600 vs Alloy 601: A Comprehensive Comparison

Shaanxi Shangyou Stainless Steel Co., Ltd. supplies both Nickel Alloy 600 (UNS N06600) and Nickel Alloy 601 (UNS N06601) in plate, sheet, round bar, and tube forms. These two nickel-chromium alloys are widely used in thermal processing and chemical industry environments, but they are optimized for different performance priorities. Alloy 600 is a standard Ni-Cr-Fe alloy valued for broad corrosion resistance, strong mechanical properties, and versatility across a very wide temperature range. Alloy 601 is specifically designed for superior oxidation resistance at elevated temperatures, supported by its higher chromium content and the addition of aluminum. Both alloys are available with EN 10204 3.1 MTC, PMI testing, and full traceability.

Alloy 600 is a solid-solution strengthened nickel-chromium-iron alloy with a minimum nickel content of 72%. The high nickel content provides immunity to chloride-ion stress corrosion cracking in many environments, while chromium (14-17%) contributes resistance to sulfur compounds and oxidizing conditions, both at high temperature and in certain corrosive solutions. The alloy is not precipitation hardenable; strength can be increased through cold work. This makes Alloy 600 a proven choice for chemical processing equipment, heaters, distillation units, and heat exchangers where corrosion resistance and reliability are required.

Alloy 601 is also a solid-solution strengthened alloy, but it was specifically developed with higher chromium content (21-25%) and the addition of aluminum (1.0-1.7%) to provide outstanding oxidation resistance at elevated temperatures. The aluminum addition forms a protective oxide layer that enhances performance in high-temperature oxidizing environments. Alloy 601 is often selected when oxidation resistance at high temperature is the key driver, for example in furnace parts, burner components, and radiant tube applications. It also offers good resistance to many forms of corrosion, good mechanical strength, and good fabricability.

The Alloy 600 Advantage:

• Virtually immune to chloride-ion stress corrosion cracking due to high nickel content (72% min)
• Good resistance to many organic and inorganic media
• Excellent mechanical stability across a wide temperature range
• Proven reliability in chemical processing equipment

The Alloy 601 Advantage:

• Superior oxidation resistance due to higher chromium (21-25%) and aluminum (1.0-1.7%) content
• Better pitting resistance – studies show pitting potential for Alloy 601 is almost 200 mV more positive than Alloy 600 in chloride-containing acidic environments
• Superior corrosion resistance in sulfuric acid – shows substantially higher corrosion resistance than Alloy 600 in H₂SO₄ solutions
• Spontaneous passivation – Alloy 601 shows rapid passivation from rest potential itself in many acid concentrations, while Alloy 600 typically requires an Icrit-Ipass transition
• Better resistance to carburization at elevated temperatures

• Alloy 600 offers good oxidation resistance up to approximately 1,093°C (2,000°F) and is suitable for many high-temperature applications
• Alloy 601 delivers outstanding oxidation resistance up to approximately 1,200°C (2,200°F) with excellent resistance to thermal cycling and spalling

• Alloy 600 provides good resistance in many environments and is practically immune to chloride SCC
• Alloy 601 shows better resistance in sulfuric acid solutions, with corrosion current measurements indicating better corrosion resistance for Alloy 601 than Alloy 600
• In chloride-containing acidic environments, Alloy 601 exhibits superior pitting resistance

Both alloys are solid-solution strengthened and not age-hardenable:

• Alloy 600: Annealed tensile strength 550-690 MPa, good ductility (30-55% elongation)
• Alloy 601: Annealed tensile strength 550-790 MPa, excellent ductility (35-65% elongation)

Choose Alloy 600 when:

• Service temperature is below 1,000°C
• Chloride SCC resistance is the primary concern
• The application involves chemical processing or caustic alkali handling
• Broad corrosion resistance in a wide range of media is required
• Proven reliability with a long service history is preferred

Choose Alloy 601 when:

• Service temperature exceeds 1,000°C
• Superior oxidation resistance is critical, especially with thermal cycling
• Resistance to carburization at high temperature is required
• Sulfuric acid or other aggressive environments are involved
• The application demands the highest high-temperature performance

For a detailed quotation or material selection assistance, please provide:

Alloy Grades Under Consideration · Required Standard · Product Form · Dimensions · Quantity · Service Conditions (Temperature, Medium, Pressure) · Application · Destination Port

For high-temperature or corrosive service, also provide:

Operating Temperature · Cyclic Heating Requirements · Chemical Medium · Oxidizing or Reducing Conditions

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• Request Alloy 601 Quote
• Request Alloy Selection Support
• Upload Drawing or MTO

Alloy 600 is a versatile Ni-Cr-Fe alloy valued for broad corrosion resistance and immunity to chloride SCC. Alloy 601 was specifically developed with higher Cr and Al for superior oxidation resistance at high temperatures.

Alloy 601 has significantly better oxidation resistance due to its higher chromium content (21-25% vs 14-17%) and aluminum addition (1.0-1.7%).

Studies show Alloy 601 has substantially higher corrosion resistance than Alloy 600 in sulfuric acid solutions. Alloy 601 shows spontaneous passivation in many acid concentrations, while Alloy 600 requires a transition state before passivation.

Alloy 601 exhibits better pitting resistance. The pitting potential for Alloy 601 is almost 200 mV more positive than Alloy 600 in chloride-containing acidic environments.

Alloy 600 is virtually immune to chloride-ion stress corrosion cracking due to its high nickel content (72% min). Alloy 601 also offers good resistance but is not as proven in this specific aspect.

Alloy 600 offers good oxidation resistance up to approximately 1,093°C (2,000°F). Alloy 601 provides outstanding oxidation resistance up to approximately 1,200°C (2,200°F).

No. Both Alloy 600 and Alloy 601 are not precipitation hardenable and can only be strengthened through cold working.

Alloy 601 offers superior resistance to carburization at elevated temperatures compared to Alloy 600.

Alloy 600 is more widely established with a longer service history, but both alloys are readily available in plate, sheet, bar, and tube forms.

Please provide the application, operating temperature, chemical medium (if corrosive), whether thermal cycling is involved, and the required strength. Our team can provide expert guidance based on your specific service conditions.