Chemical composition of 00Cr20Ni18Mo6CuN (254SMO) steel

254 SMO is a super austenitic stainless steel developed by Western European steel producers in the 1980s by combining the properties of two austenitic stainless steels such as alloy 20 and 25.

Its an alloy of chromium-nickel-molybdenum-copper-nitrogen, created to overcome the limitations of alloys such as 309 and 310, offering equal or improved corrosion resistance. 254 SMo is, however, a type of stainless steel with a higher alloys content, making it more expensive as well as featuring a higher resistance to corrosion in comparison with conventional austenitic stainless steels. It also has excellent pitting corrosion resistance and high mechanical strength.

Chemical Composition of 254 SMO:

C (Carbon) 0.020 max

Mn (Manganese) 2.00 max

P (Phosphorus) 0.040 max

Si (Silicon) 1.00 max

S (Sulphur) 0.030 max

Cr (Chromium) 20.0-22.0

Mo (Molybdenum) 6.00-6.50

Ni (Nickel) 17.0-19.0

N(Nitrogen) 0.18-0.25

Cu (Copper) 0.50-0.80

The difference between 254 SMO and other austenitic alloys is due to the presence of the higher number nitrogen and molybdenum elements contained in the alloy. This results in providing increased resistance to pitting and crevice corrosion, higher mechanical strength and resistance to stress corrosion cracking.

From a mechanical point, 254 SMO can be tempered using three methods, namely solution annealing, low temperature annealing, and solution annealing plus low-temperature ageing. In terms of welding, 254 SMO is much easier to weld than other high-alloy austenitic stainless steels, while special techniques such as post-weld heat treatment may be used to increase its corrosion resistance.

In conclusion, 254 SMO is a premium grade, super austenitic stainless steel created in the 1980s which combines the properties of alloy 20 and 25, offering clients a vastly improved corrosion resistance at a higher price. Its combination of elements and the addition of nitrogen and molybdenum, as well as its medium-high mechanical strength, makes it an ideal choice for industrial applications, such as petrochemical, pharmaceutical, food and marine industries.

1. Introduction

254SMO (Cr20Ni18Mo6CuN) is a high alloy austenitic stainless steel with a Global Unique Material (GUM) number. It is an exceptionally corrosion resistant, high-performance material, providing reliable and long-lasting service in aggressive environments.

2. Chemical Composition

The chemical composition composition of 254SMO Stainless Steel is outlined in the following table.

C: ≤0.030

Mn: ≤2.00

Si: ≤1.00

P: ≤0.035

S: ≤0.010

Cr: 18.0-20.0

Ni: 15.0-18.0

Mo: 6.0-8.0

Cu: 0.5-1.0

N: 0.08-0.25

3. Mechanical Properties

The mechanical properties of 254SMO Stainless Steel are as follows:

Tensile Strength: ≥650 Mpa

Yield Strength: ≥250 Mpa

Elongation: ≥50 %

4. Features and Applications

254SMO stainless steel has superior pitting, crevice, and stress corrosion cracking resistance. This, combined with its good formability, results in its use in a wide variety of applications, such as pressure vessels, food processing, and oil and gas industry.

5. Conclusion

In conclusion, 254SMO stainless steel is a high alloy grade of stainless steel with superior corrosive properties and good formability. It has applications in a wide range of industries, including pressure vessels, food processing, and oil and gas.