347H stainless steel chemical composition

Alloy 347H is a stabilized, austenitic, chromium steel containing columbium which allows for the elimination of carbide precipitation, and, consequently, intergranualr corrosion. Alloy 347 is stabilized by the additions of chromium and tantalum and offers higher creep and stress rupture properties than alloy 304 and 304L which may also be used for exposures where sensitization and intergranualr corrosion are of concern. The addition of columbium also allows Alloy 347 to have excellent corrosion resistance, even superior to that of alloy 321.  347H is the higher carbon composition form of Alloy 347 and demonstrates improved high temperature and creep properties. Haosteel Stainless inventory now includes Alloy 347/347H (UNS S34700/S34709) in sheet, sheet coil, plate, round bar, processed flat bar and tubular products.

 347H stainless steel chemical composition

Chemical composition:

347H stainless steel chemical composition

Physical Properties:

Annealed:
Ultimate Tensile Strength – 75KSI min (515 MPA min)
Yield Strength (0.2% Offset) –30 KSI min (205 MPA min)
Elongation – 40% min
Hardness – HRB92max (201HV max) 

Applications

Alloy 347H is frequently used for the fabrication of equipment, which must be placed in service under severe corrosive conditions, and is also common to the petroleum refining industries.

Corrosion Resistance:

. Offers similar resistance to general, overall corrosion as Alloy 304

. Used for applications where alloys such as Alloy 304 are vulnerable to intergranualr corrosion

. Generally used for heavy welded equipment which cannot be annealed and for equipment

which is operated between 800 to 150°F (427 TO 816°C)

. Alloy 347 is preferred over Alloy 321 for aqueous and other low temperature environments

. Primarily used in high temperature environments where resistance to sensitization is necessary, in turn preventing intergranualr corrosion at lower levels

. Susceptible to stress corrosion cracking

. Exhibits oxidation resistance similar to all other 18-8 austenitic stainless steels