Difference Between 347 and 347H Stainless Steel:
347 stainless steel has a carbon content of 0.08% or less, while 347H stainless steel has a carbon content between 0.04% and 0.10%.
1. Carbon Content:
Alloy 347 / UNS S34700 / 1.4550 typically contains a lower carbon content compared to 347H stainless steel. This lower carbon content in 347 stainless steel helps to improve its weldability and corrosion resistance, particularly in high-temperature applications.
2. Heat Treatment:
Alloy 347H / UNS S34709 / 1.4961 is the high carbon version of 347 stainless steel. The "H" in 347H stands for high carbon content. The higher carbon content in 347H stainless steel enhances its strength and high-temperature properties. It also makes the material more suitable for applications where elevated temperature strength is required.
3. Weldability:
Due to its lower carbon content, AISI 347 stainless steel offers better weldability compared to 347H stainless steel. The reduced carbon content minimizes the formation of chromium carbide precipitation at the grain boundaries during welding, which can lead to intergranular corrosion and reduced mechanical properties.
4. Creep Resistance:
SUS 347H stainless steel pipe, with its higher carbon content, demonstrates improved creep resistance compared to 347 stainless steel. Creep resistance refers to the ability of a material to resist deformation under constant load at high temperatures over an extended period. This makes 347H more suitable for applications involving prolonged exposure to elevated temperatures.
5. Applications:
Both 347 and 347H stainless steels are commonly used in high-temperature applications, such as in the manufacturing of equipment for the petrochemical, chemical, and power generation industries. However, 347H stainless steel is preferred in applications where higher strength and creep resistance at elevated temperatures are critical.
In summary, while both 347 and 347H stainless steels offer excellent corrosion resistance and are suitable for high-temperature applications, the difference lies in the carbon content, with 347H having a higher carbon content and therefore exhibiting enhanced strength and high-temperature properties.
