0Cr18Ni11Nb (AISI347) process performance

Introduction

Stainless steel AISI 347, also known as 0Cr18Ni11Nb, is a type of austenitic stainless steel alloy that contains titanium and niobium. The combination of titanium and niobium improves its mechanical properties, making it highly resistant to intergranular corrosion. It also has a good formability compared to low-alloyed stainless steels.

Chemical Composition

The chemical composition of AISI 347 stainless steel is given in the following table.

C 0.04

Si 1.00

Mn 2.00

P 0.045

S 0.030

Cr 17-20

Ni 9-13

Nb 5×C

Ti 0.5-1.5

Mechanical Properties

The mechanical properties of AISI 347 stainless steel are summarized in the following table.

Tensile Strength (ksi) 70

Yield Strength 0.2% Offset (ksi) 35

Elongation in 2″ (%) 25

Hardness Rockwell B 75

Hardness Vickers 150-200

Applications

AISI 347 stainless steel has a variety of applications. It is used in food processing equipment and cookware due to its improved formability and resistance to corrosion. Additionally, it is used in automotive components, marine hardware, chemical processing equipment, and paper mills. Due to its excellent mechanical properties, it is favored for parts that require highly wear-resistant parts.

Heat Treatment

AISI 347 stainless steel is a low-carbon iron-chromium-nickel stainless steel that has been treated with niobium and titanium to improve its resistance to intergranular corrosion. The addition of niobium further enhances the alloys durability and mechanical properties.

The heat treatment of AISI 347 is similar to other austenitic stainless steels. It is typically heated in a temperature range of 1450-1600 °F (788-871 °C), followed by a water quench. It is then cooled at room temperature to form a martensitic microstructure. Additionally, the steel can be given a higher hardness by reheating after quenching to a temperature that ranges from 500-1040 °F (260-560°C). The steel is then cooled again in a cooldown process.

Welding

AISI 347 stainless steel can be welded using inert gas arc welding (TIG welding) or shielded metal-arc welding (MIG welding). The preferred electrode is a structure electrode made from a low-hydrogen-content, low-alloy steel. The steel should be preheated at 342-482°F (175-250°C) for a period of 1/2 to 4 hours prior to welding. This will reduce cracking and ensure minimum levels of hydrogen in the weld.

Conclusion

AISI 347 stainless steel is an austenitic stainless steel alloy that contains titanium and niobium. This combination improves the mechanical properties of the alloys, making it more resistant to intergranular corrosion than other stainless steels. It also has improved formability compared to low-alloyed stainless steels. AISI 347 stainless steel is used in food processing equipment, cookware, automotive components, marine hardware, chemical processing equipment, and paper mills. It is also weldable using TIG welding and MIG welding. The steel should be preheated prior to welding to reduce cracking and ensure minimum levels of hydrogen in the weld.

AISI347 stainless steel has great weldability, good corrosion resistance and high temperature strength, which makes it suitable for many applications, such as aircraft exhaust systems, furnace parts, bearings, and so on.

AISI347 stainless steel is heat treated in an austenitic state to obtain good characteristics. It has excellent toughness even in cryogenic temperatures and is resistant to sensitization, making it suitable for welding components that are subjected to high temperature operations. The high chromium content of AISI347 gives it a good oxidation resistance and it is also resistant to some environments containing acids, alkalis and salt.

Due to its good properties, it is the preferred material for thermal and chemical processing equipment, such as industrial reactors and autoclaves. It also has good properties when used in pressure operated equipment, such as valves, turbine impellers and heat exchangers, as it has good resistance to cracking and corrosion.

AISI347 stainless steel has good mechanical properties at elevated temperatures, and its strength is resistant to rapid cooling. The thermal shock resistance of AISI347 stainless steel is much better than other alloys, making it suitable for use in areas with extreme temperature changes.

AISI347 stainless steel is also suitable for cryogenic applications, and it has a low thermal conductivity, making it suitable for cryogenic storage tanks, piping and fittings. The low thermal expansion and high fatigue strength of AISI347 make it suitable for parts subjected to thermal and vibration stress.

AISI347 stainless steel is a versatile alloy that provides excellent performance in a wide range of applications. With its excellent properties, it is ideal for many applications, such as aircraft exhaust systems, furnace parts, bearings and many more.