Type 347 (UNS S34700)


Type 347 is a niobium stabilized chromium nickel austenitic stainless steel with corrosion resistance similar to 304/304L. This grade is typically used in the 800-1500˚F temperature range where it is stabilized against chromium carbide precipitation by the addition of niobium, which results in the precipitation of niobium carbides. Type 347 has excellent intergranular corrosion resistance after exposure to this temperature range, and this grade resists oxidation up to 1500˚F and has higher creep and stress rupture properties than 304/304L. It also possesses good low temperature toughness and is non-magnetic in the annealed condition.

Chemical Composition
Chemical Composition (wt%) limits as specified in ASTM A240 and ASME SA240*.
Element 347
Carbon 0.08
Chromium 17.0-19.0
Nickel 9.0-13.0
Manganese 2.00
Silicon 0.75
Phosphorus 0.045
Sulfur 0.030
Niobium 10 x C min / 1.00 max
* Maximum, unless range is indicated
Mechanical Properties
Mechanical property requirements for annealed product as specified in ASTM A240 and ASME SA240.
Property 347
Yield Strength, min. (ksi) 30
Tensile Strength, min. (ksi) 75
Elongation, min. (%) 40
Hardness, max. (Rb) 92
Physical Properties
Physical properties for Type 347 stainless steel
Property 347 Data
Density, lb/in3 0.288
Modulus of Elasticity, psi 28.0 x 106
Coefficient of Thermal Expansion, 68-212˚F, /˚F 9.3 x 10-6
Thermal Conductivity, Btu/ft hr ˚F 9.2
Specific Heat, Btu/lb ˚F 0.12
Electrical Resistivity, Microohm-in 28.4
Typical standards for Type 347 stainless steel
AMS 5512

Data are typical, are provided for informational purposes, and should not be construed as maximum or minimum values for specification or for final design, or for a particular use or application. The data may be revised anytime without notice. We make no representation or warranty as to its accuracy and assume no duty to update. Actual data on any particular product or material may vary from those shown herein.  © 2014 RMP Inc. All rights reserved.