SS 347 / UNS S34700 / W.Nr. 1.4550
Stainless Steel 347
ALLOY 347 / STAINLESS STEEL 347
Stainless Steel 347 (also known as Alloy 347 or SS 347), is a type of austenitic stainless steel that offers improved corrosion resistance compared to its counterpart, Type 321. The addition of columbium stabilizes the steel and makes it ideal for use in aqueous and low temperature environments where it exhibits good resistance to intergranular attack. Additionally, both Stainless Steel 347 and 321 offer resistance against polythionic acid stress corrosion cracking, a common issue encountered in oil refineries.
This versatile alloy is highly sought after due to its high temperature oxidation resistance, which is similar to that of 304 stainless steel. It has the ability to withstand temperatures up to 1500°F, making it an ideal material for various high-heat applications. Moreover, the grain size and carbon content of Stainless Steel 347 can meet both the 347S and 347H standards.
For welding purposes, AWS ER347 bare wire and E347 covered electrodes are considered appropriate filler materials. As a result of its high-performance properties, Stainless Steel 347 is widely used in various industries such as petrochemical, aerospace, and power generation. Whether it’s for resistance against corrosion, heat resistance, or stress cracking, Stainless Steel 347 proves to be a reliable and durable choice.
Alloy 347 Inventory
|Product Form||Size range from||Size range to|
Alloy 347 pipe
|0.5 in||8 in|
Alloy 347 tube
|12 mm||260 mm|
Alloy 347 pipe fittings
|0.5 in||8 in|
Alloy 347 flanges
|0.5 in||8 in|
Industries and Applications
Stainless Steel 347 is a type of austenitic stainless steel that is highly valued for its exceptional resistance to corrosion, heat and stress cracking. This versatile metal is used in a wide range of industries, making it a popular choice for a variety of applications. Here are some of the most common industries and applications for Stainless Steel 347.
Petrochemical Industry: In the petrochemical industry, Stainless Steel 347 is widely used due to its ability to withstand high temperatures and resist corrosion caused by harsh chemicals. This makes it an ideal material for various applications such as storage tanks, heat exchangers, and pipelines.
Aerospace Industry: The aerospace industry relies on materials that are strong, lightweight, and able to withstand harsh environments. Stainless Steel 347 is an excellent choice for various aerospace applications due to its high strength-to-weight ratio and ability to resist corrosion. This makes it an ideal material for aerospace components such as turbines and engine parts.
Power Generation Industry: Power plants are often subjected to high temperatures and corrosive environments, making it essential to use materials that can withstand these conditions. Stainless Steel 347 is widely used in the power generation industry for various applications such as boilers, heat exchangers, and piping systems due to its heat resistance and resistance to corrosion.
Construction Industry: Stainless Steel 347 is a popular material for various construction applications due to its strength, durability, and resistance to corrosion. This makes it an ideal material for applications such as facades, cladding systems, and architectural features.
Medical Equipment: The medical industry requires materials that are both safe and durable. Stainless Steel 347 is a popular material for medical equipment such as surgical instruments, medical implants, and medical devices due to its biocompatibility and resistance to corrosion.
Resistance to Corrosion
SS 347 is well-known for its resistance to corrosion and various forms of stress. This versatile metal is widely used in various industries due to its exceptional properties, including its resistance to corrosion and its ability to withstand high temperatures.
Resistance to Corrosion: One of the key benefits of Stainless Steel 347 is its resistance to corrosion. This alloy contains columbium, which stabilizes the steel and makes it resistant to intergranular attack in aqueous and low temperature environments. Additionally, Stainless Steel 347 offers resistance against polythionic acid stress corrosion cracking, a common issue encountered in the petrochemical industry.
Resistance to Heat: In high-heat environments, materials must be able to withstand high temperatures without losing their strength or becoming damaged. Stainless Steel 347 has a high temperature oxidation resistance that is similar to that of 304 stainless steel, making it an ideal material for high-heat applications. It is capable of withstanding temperatures up to 1500°F.
Resistance to Stress: Stainless Steel 347 is also well-known for its resistance to various forms of stress, including stress corrosion cracking. This makes it an ideal material for applications that are subjected to high levels of stress and exposure to corrosive environments.
Fabrication and Heat Treatment
The fabrication and heat treatment of SS 347 are critical factors that determine its final properties and suitability for specific applications.
Fabrication: The fabrication of Stainless Steel 347 is relatively straightforward, as it can be easily formed and fabricated using common metalworking techniques. It can be hot or cold worked, and can be welded using appropriate welding techniques. Some of the common fabrication methods used for Stainless Steel 347 include forging, stamping, bending, and cutting.
Heat Treatment: The heat treatment of Stainless Steel 347 involves the controlled heating and cooling of the metal to achieve specific properties. The most common heat treatment methods used for this alloy include annealing, solution annealing, and stress relief annealing. Annealing is used to soften the metal, improve its ductility, and restore its original properties. Solution annealing is used to dissolve carbides and improve the alloy’s corrosion resistance. Stress relief annealing is used to relieve internal stresses caused by fabrication, welding, or heat treatment.
Stainless Steel 347 – Applicable Specifications
Stainless Steel 347 Plate & Sheet
Stainless Steel 347 Strip
Stainless Steel 347 Bar
Stainless Steel 347 Pipe
Stainless Steel 347 Tube
Stainless Steel 347 Fitting
Stainless Steel 347 Forging
Stainless Steel 347 Wire
Stainless Steel 347 Welding Electrode
Common Trade Names
Stainless Steel 347 is also commonly known by trade names such as Alloy 347, SS 347, and UNS S34700. Some of the other trade names for this alloy include Chromium Nickel Steel, stabilized with Columbium, and Nicrofer 5621.
(in annealed condition)
|Tensile Strength (MPa)||515 min|
|Yield Strength (MPa)||205 min|
|Elongation||40% min. in 50mm|
|Hardness (HRB)||95 max|
Chemical Composition (%)
|Columbium||10xC min.-1.10 max.|
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