2Cr17Ni2Nb vs AISI 431

Understand 2Cr17Ni2Nb steel and know everything from composition to the manufacturing products, equivalent, and its uses. Also find how this Chinese-grade 2Cr17Ni2Nb material is different from AISI 431 stainless steel.

What is 2Cr17Ni2Nb?

2Cr17Ni2Nb is a martensitic precipitation hardening alloy which is also known as 17-7PH stainless steel. 2Cr17Ni2Nb is a Chinese grade of Martensitic Stainless Steel.

2Cr17Ni2Nb has almost similar properties when compared to SS 431 grade except for the addition of niobium. 2Cr17Ni2Nb steel contains 0.10% – 0.30% Niobium (Nb). This element enhances the overall strength and toughness of this alloy.

Other hand, AISI 431 also belongs to the Martensitic Stainless Steel group. But this grade has few differences in terms of properties and chemical composition.

Top 9 reasons to use 2Cr17Ni2Nb alloy in Structural and Industrial applications

In some specific conditions project engineers prefer to choose 2Cr17Ni2Nb over AISI 431. Here are those top 9 reasons:

• Superior Corrosion Resistance
• Temperature Stability
• Better Weldability
• High Toughness due to the addition of Niobium
• Better Tensile Strength
• Impact Resistance
• Lower Carbon Content
• Resistance to Stress Corrosion Cracking
• Cost-effective

2Cr17Ni2Nb stainless steel T channel bar is the most popular product type among construction projects. These SS 2cr17ni2nb C Channel and U Channel are manufactured with Cutting, De-coiling, Welding, Bending, and Punching processes.

2Cr17Ni2Nb construction channel steel cost approx. between a range of US $400 to US $550 per ton depends upon the manufacturers. Other hand, SS 431 T channel bars may cost between US $440- $480 per ton.

Chinese-grade 2Cr17Ni2Nb comparison with American equivalent AISI 431

Check the following table to view their equivalent name in different countries.

Comparison of 2Cr17Ni2Nb and 431 Stainless Steel Chemical Composition

Advantages and disadvantages to using 2Cr17Ni2Nb Steel in high-temperature environments

The main advantage is its Heat Resistance properties. Because of it 2Cr17Ni2Nb products are most suitable for high-temperature industrial projects. This material has better corrosion resistance compared to AISI 431 and can sustain longer. Furthermore, 2Cr17Ni2Nb grade has high tensile and yield strength which make it suitable for use in harsh environments. These products can be used in various sectors such as marine, chemical processing and industrial structural.

Other hand, this material has a few limitations and disadvantages. Like 2Cr17Ni2Nb stainless steel becomes brittle at low temperatures. The other limitation of this alloy is difficulty in machining and welding after quenching and tempering. Even these products can crack during welding. So, after the heat treatment process this steel grade requires special tools and advanced welding techniques. And after welding, Post-Weld Heat Treatment (PWHT) is highly recommended for better joints.

Common Advantages and disadvantages

Advantages

• Widely used in high-temperature industrial projects
• better corrosion resistance
• high tensile and yield strength
• Long sustain life
• Suitable for marine, chemical processing and industrial structural projects

Disadvantages

• difficulty in machining and welding
• Require special tools to machine
• Require Preheating before welding
• Require Post-Weld Heat Treatment (PWHT)

Tips for Welding Chinese-grade 2Cr17Ni2Nb

As 2Cr17Ni2Nb hardening alloy can be cracked during the welding process. So, here are some useful tips to weld 2Cr17Ni2Nb products.

• Preheating: Preheating is required If the products are formed with heat treatment process
• PWHT: Go for a post-weld heat treatment (PWHT) to reduce stress and restoring of mechanical properties
• Selection of correct filler metal and welding consumables
• The job should be performed by a skilled welder

Selection of welding consumables

Applications and uses of 2Cr17Ni2Nb Martensitic Stainless Steel

2Cr17Ni2Nb stainless steel can be formed in various types of industrial products such as fasteners, bolts and nuts, components, channel, fittings, pipes, tubes, and valves.

These 2Cr17Ni2Nb made industrial materials are widely used in Chemical Processing, Aerospace, Automotive, Petrochemical, Marine, Oil & Gas, Power Generation, and Nuclear Plants.

2Cr17Ni2Nb products and their applications

There are various products manufactured from 2Cr17Ni2Nb steel used for industrial projects. A few most common products and uses are listed below.

List of acids and chemicals where 2Cr17Ni2Nb is the preferable choice

• Sulfuric Acid (H₂SO₄)
• Nitric Acid (HNO₃)
• Hydrochloric Acid (HCl)
• Phosphoric Acid (H₃PO₄)
• Acetic Acid (CH₃COOH)
• Chlorine (Cl₂)
• Sodium Hydroxide (NaOH)
• Ammonia (NH₃)
• Hydrogen Sulfide (H₂S)

2Cr17Ni2Nb Bar Mechanical Properties accordance to ASTM A564

Conclusion

So, 2Cr17Ni2Nb and AISI 431 both are stainless steel but due to their unique technical specifications, these grades are used for specific purpose. Before making a selection, project engineers compare their quality, budget, availability, and properties.