Stainless Steel 347

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Stainless Steel 347

Type 347 stainless steel has slightly improved corrosion resistance over type 321 stainless steel in strongly oxidizing environments. Type 347 is stabilized with columbium, it is preferable for aqueous and low temperature environments due to its good resistance to intergranular attack. Both 347 and 321 offer good resistance to polythionic acid stress corrosion cracking, encountered in oil refineries. The high temperature oxidation resistance of 347 is similar to that of 304 stainless steel. Useful to 1500°F. ss-347
Often in many product forms, the grain size and carbon content can meet both the 347S and 347H requirements. Appropriate weld fillers are AWS ER347 bare wire and E347 covered electrodes.

Physical Properties

Density: 0.286
lb/inch3 
Melting Point: 2550
– 2635°F

Temperature, °F 70 212 932
Coefficient* of Thermal Expansion, in/in°F x 10-6 - 9.2 -
Thermal Conductivity
Btu • ft/ft2 • hr • °F
- 112.5 147.7
Modulus of Elasticity, Dynamic psi x 106 28 - -

* 70°F to indicated temperature.

Mechanical Properties

Minimum Specified Properties, ASTM A 240

Tensile Strength, ksi 75
0.2% Yield Strength, ksi 30
Elongation, % 40
Hardness Max, Brinell 201

Chemistry

Cr Ni Cb + Ta C Si Mn P S Fe
MIN 17.0 9.0 Cb 10xc
(Cb 8xC)
0.04 - - - -
MAX 19.0 13.0 1.0 0.08 0.75 2.0 0.045 0.03 Balance