What do the acronyms commonly used in forging mean? 

ASME/ASTM S/A105 is a standard specification for carbon and low-alloy steel forgings components such as flanges and fittings. These forgings are primarily supplied in two heat treatment conditions.

• As Forged: (A105) The “As Forged” condition is only allowed in classes 150 and 300 for flanges.
• Normalized: (A105N) Normalization is a heat treatment process used to improve the mechanical properties and microstructure of a metal.

The heat treatment process requires heating the material to above the transformation temperature, holding it, and then allowing it to cool in still air. Normalization is required for flanges class 400 and above. Flanges in classes 150 and 300 normalization is optional. Normalized flanges can be manufactured using “Fine Grain Practice”. This practice normally involves the addition of one or more austenitic grain refining elements in amounts that have been established by the steel producer as being sufficient. Austenitic grain refining elements include but are not limited to, aluminum, niobium (columbium), titanium, and vanadium. Some end users have made fine grain practice a requirement.

ASME/ASTM S/A350 LF2 is a specification for carbon and low-alloy steel forgings and is used for applications requiring impact toughness and resistance to brittle fracture at low temperatures. LF2 steel can maintain its mechanical properties and resistance to brittle fracture even under sub-zero conditions (-50°F), making it suitable for liquid natural gas applications. Most LF2 flanges are manufactured using fine-grain practice. Additionally, some manufacturers produce a forging that meets all the requirements of LF2 and A105.

ASME/ASTM S/A182 specification contains the requirement for a wide range of alloys. These are some of the more common grades:

• Chrome alloys
  • F11        1-1/4 Cr 1/2Mo Alloy
  • F22        2-1/4Cr 1Mo Alloy
  • F5           5 Cr 1/2Mo Alloy
  • F9           9 Cr 1Mo Alloy
  • F91        9 Cr 1Mo V Alloy
• Austenitic Stainless Steel
  • F304     18Cr 8Ni
    • F304L   Low Carbon Variant
    • F304H High Carbon Variant
    • F304/F304L Dual Grade (meets the requirements of both low carbon and standard F304)
  • F316     16Cr 12Ni 2Mo
    • F316L   Low Carbon Variant
    • F316H High Carbon Variant
    • F316/F316L Dual Grade (meets the requirements of both low carbon and standard F316)