Stainless Steel 347 - Alloy Composition

 

Stainless Steel 347 has slightly improved corrosion resistance over type 321 stainless steel in strongly oxidizing environments. Alloy 347 is a columbium(niobium)/tantalum stabilized austenitic chromium-nickel stainless steel which was developed to provide an 18-8 type alloy with improved intergranular-corrosion resistance. Alloy 347 has a slightly improved corrosion resistance over other alloys of stainless steel in strongly oxidizing environments as a result of the addition of columbium (niobium) and tantalum. Columbium-tantalum carbides precipitate within the grains instead of forming at the grain boundaries. Type 347 should be considered for applications requiring intermittent heating between 800ºF (427ºC) and 1650ºF (899ºC), or for welding under conditions which prevent a post-weld anneal.

Nominal Composition in Percentage:

Ni                     11.00

Cr                    18.00

Fe                    Balance

Si                     1.00

Mn                    2.00

C                      0.080

P                      0.045

S                      0.030

Cb+Ta              10 x C

 

UNS Number:

S34700

Other Standard Specifications:

AMS 5512

300 Series—austenitic chromium-nickel alloys

Density:

  0.29 lbs/in

Exceptional Properties:

Toughness, durability, corrosion resistance, weldability, high temperature, high creep and stress rupture properties.