High temperature mechanical properties of 0Cr19Ni9N (AISI304N) and 00Cr18Ni10N (AISI3041N)

Introduction

304N and 304LN stainless steels are commonly used as materials for high temperature applications due to their creep resistance and corrosion resistance. They are both austenitic stainless steel, but with different compositions. The 304N is an austenitic stainless steel with a nominal composition of 0.08% carbon, 19.0-21.0% chromium, 9.0-13.0% nickel, 0.5-2.5% molybdenum, 0.25-0.5% nitrogen, and balance iron. Unlike Type 304, Type 304N re-ages very slowly and thus retains its strength at high temperatures even after a long exposure.

The 304LN composition is similar to that of the 304N, but with a lower nitrogen content. A lower nitrogen content gives it better intergranular corrosion resistance after welding. It also allows for easier processing and formability. Type 304LN also has a lower ferromagnetic response than Type 304N.

Tensile and Creep Properties

Tensile strength is a measure of the resistance of a material to being pulled apart when placed under tension. The tensile strength of both 304N and 304LN stainless steel is the same, at 521 MPa.

Creep is the deformation of a material over time under a constant stress. The creep properties of 304N and 304LN stainless steel depend on the rate of loading. At a slow rate of loading, both materials reach a maximum creep strain of 6%. At faster loading rates, the creep strain of 304N is higher than that of 304LN. At a loading rate of 7 MPa/second, the maximum creep strain of 304N is 8% while that of 304LN is 7%.

High Temperature Toughness

Toughness is the ability of a material to resist brittle fracture when subjected to tension. The high temperature toughness of 304N is higher than that of 304LN. At temperatures above 600 °C, 304N stainless steel has an impact toughness of 34 J/cm2 while 304LN has an impact toughness of 26 J/cm2.

Corrosion Resistance

Type 304N stainless steel is more resistant to corrosion than type 304LN. This is due to its higher nitrogen content, which provides better protection against corrosion. Both materials are highly resistant to acidic and alkaline solutions, but 304N is more resistant to chlorine solutions due to its higher nitrogen content.

Conclusion

The mechanical properties of 304N and 304LN stainless steel are similar in many respects, but they have different compositions. Type 304N has higher tensile strength and higher creep strain than type 304LN. Type 304N also has higher high temperature toughness and is more resistant to corrosion than type 304LN. The different compositions of these stainless steel types make them suitable for different high temperature applications.

AISI 304N and AISI304N are two common austenitic stainlesssteel materials with different alloy content and chemical composition. AISI304N is a nitrogen-strengthened version of the USA standard grade AISI304 (S30400 stainless steel). AISI304N contains about 8 % of nitrogen, making it the strongest of the 300 series stainless steels. On the other hand, AISI304LN is an austenitic stainless steel of the 18 % chromium, 10 % nickel, and 2 % molybdenum alloy content. AISI304LN is low carbon, making it resistant to intergranular corrosion, as well as having excellent welding characteristics.

When evaluating the mechanical properties of AISI 304N and AISI304N at high temperatures, both have proven to be excellent materials for use in elevated temperature applications. They both exhibit high tensile strength, outstanding ductility, and excellent fatigue resistance at temperatures up to 800°C. AISI304N exhibits slightly higher creep strength, while AISI304LN has better strength properties than AISI304N in the temperature range of 400°C – 800°C. Furthermore, both alloys retain good strength values up to 1000°C.

In conclusion, both AISI 304N and AISI304LN exhibit outstanding mechanical properties at elevated temperatures. AISI304N has high tensile strength, excellent ductility and creep strength, while AISI304LN has better strength properties, specifically in the 400°C-800°C range and both maintain good strength values even up to 1000°C. Therefore, AISI 304N and AISI304LN are excellent materials for use in high temperature applications.