Austenitic Stainless Steel Bellows Materials - Bellows systems

Austenitic stainless steels are iron-based alloys containing Chromium and Nickel and are widely available in various types having different compositions and material properties. They are the most commonly used material for metal bellows and expansion joints. Stainless steel bellows offer versatility in terms of their ability to withstand high temperature and high pressure and provide good corrosion protection. Types 304/304L, 316/ 316L and 321 are the standard bellows materials and Bellows Systems commonly stocks a wide range of sheet thickness ranging from 0.005″ to 0.062″.

Stainless Steel 302 (UNS: S30200)

Bellows Materials SS 302
Description Austenitic chromium-nickel stainless steel with higher carbon, earlier version of Type 304 stainless steel, and many on legacy parts.
Application Notes 302 applications have switched to Type 304 with the improvements in melting technology. Type 302 is corrosion resistant in many environments, and the corrosion properties are similar to that of 304/304L stainless steel. The susceptibility to carbide precipitation during welding restricts the use of Type 302 in some applications and 304L is used because of its lower carbon content for welded applications.
UNS S30200
Specifications ASTM A240, ASME SA-240, AMS 5515

Material Properties

Density, ρ, lbs/in^3 0.29
Yield Strength, Sy, Psi 30,000
Tensile Strength, Su, Psi 75,000
Elongation % 40
Poisson’s Ratio, ν 0.30
Youngs Modulus, E psi 28000000
Creep Temperature, ˚F 800
Coeff. Thermal Expansion, in/in/˚F 0.0000092

Stainless Steel 304 (UNS: S30400)

Bellows Materials SS 304
Trade Name CRES 304
Description Standard 18/8 (18% chrome, 8% nickel) austenitic stainless steel and is the most commonly used grade of stainless steels.
Application Notes It is a non-magnetic alloy in the annealed condition but becomes magnetic as it is cold worked. Alloy 304 can be easily welded and is the choice for many deep drawn, spun or formed parts due to its high ductility.
UNS S30400
Specifications ASTM A240, ASME SA-240, AMS 5513

Material Properties

Density, ρ, lbs/in^3 0.29
Yield Strength, Sy, Psi 30,000
Tensile Strength, Su, Psi 75,000
Elongation % 40
Poisson’s Ratio, ν 0.30
Youngs Modulus, E psi 28000000
Creep Temperature, ˚F 800
Coeff. Thermal Expansion, in/in/˚F 0.0000092
Melting Point, ˚F 2550

Stainless Steel 304L (UNS: S30403)

Bellows Materials SS 304L
Description Low-carbon variation of 304 making it useable in the “as-welded” condition (without annealing), even in severe corrosive conditions.
Application Notes The alloy has oxidation resistance to a maximum temperature of 1650°F (899°C) continuously without appreciable scaling. The maximum temperature for intermittent exposure is 1500°F (816°C).
UNS S30403
Specifications ASTM A240, ASME SA-240, AMS 5513

Material Properties

Density, ρ, lbs/in^3 0.29
Yield Strength, Sy, Psi 30,000
Tensile Strength, Su, Psi 75,000
Elongation % 40
Poisson’s Ratio, ν 0.30
Youngs Modulus, E psi 28000000
Coeff. Thermal Expansion, in/in/˚F 0.0000092

Stainless Steel 304H (UNS: S30409)

Bellows Materials SS 304H
Description A modified version of the widely utilized “18-8” chromium nickel austenitic stainless steel.
Application Notes The carbon content is controlled in the range of 0.04–0.10% for increased strength at temperatures above 800°F (427°C). It is an economical and versatile corrosion resistant alloy suitable for a wide range of general purpose applications. It is common practice for 304H to be dual certified as 304 and 304H. The high carbon chemistry of 304H enables 304 to meet the mechanical properties and grain size requirements of 304H.
UNS S30409
Specifications ASTM A240, ASME SA-240, AMS 5513

Stainless Steel 316 (UNS: S31600)

Bellows Materials SS 316
Description Austenitic chromium-nickel stainless steel alloy containing molybdenum. This addition increases corrosion resistance, improves resistance to pitting chloride ion solutions and provides increased strength at elevated temperatures.
Application Notes Properties of this austenitic stainless steel grade are similar to those of type 304 except that type 316 is somewhat stronger at elevated temperature ranges. 316 alloy may become magnetic when cold worked. Corrosion resistance is improved, particularly against sulfuric, hydrochloric, acetic, formic and tartaric acids, as well as corrosion caused by acid sulfates and alkaline chlorides.
UNS S31600
Specifications ASTM A240, ASME SA-240

Material Properties

Density, ρ, lbs/in^3 0.29
Yield Strength, Sy, Psi 30,000
Tensile Strength, Su, Psi 75,000
Elongation % 40
Poisson’s Ratio, ν 0.30
Youngs Modulus, E psi 28000000
Creep Temperature, ˚F 900
Coeff. Thermal Expansion, in/in/˚F 0.0000092

Post Weld Heat Treatement (PWHT)

Annealing Solution anneal at 1900-1950 °F for improved corrosion properties

Stainless Steel 316L (UNS: S31603)

Bellows Materials SS 316L
Description The low carbon version of 316 Stainless is 316L Stainless Steel which has increased resistance to intergranular corrosion.
Application Notes H2S exposure
UNS S31603
Specifications ASTM A240, ASME SA-240

Material Properties

Density, ρ, lbs/in^3 0.29
Yield Strength, Sy, Psi 30,000
Tensile Strength, Su, Psi 75,000
Elongation % 40
Poisson’s Ratio, ν 0.30
Youngs Modulus, E psi 28000000
Coeff. Thermal Expansion, in/in/˚F 0.0000092

Stainless Steel 321 (UNS: S32100)

Bellows Materials SS 321
Trade Name CRES 321
Description Austenitic chromium-nickel stainless steel containing Titanium. The titanium addition stabilizes against carbide precipitation during welding and in 800 – 1500°F (427 – 816°C) service. It also eliminates the need for an anneal after welding.
Application Notes Alloy 321 provides excellent intergrangular corrosion resistance upto 1500 °F and possesses better creep properties than 304/304L.
UNS S32100
Specifications ASTM A240, ASME SA-240, AMS 5510

Material Properties

Density, ρ, lbs/in^3 0.286
Yield Strength, Sy, Psi 30,000
Tensile Strength, Su, Psi 75,000
Elongation % 40
Poisson’s Ratio, ν 0.30
Youngs Modulus, E psi 28000000
Coeff. Thermal Expansion, in/in/˚F 0.0000093
Melting Point, ˚F 2500

Stainless Steel 347 (UNS: S34700)

Bellows Materials SS 347
Description A stabilized austenitic stainless steel similar to type 304 with an addition of Columbium and Tantalum.
Application Notes The columbium serves to produce a stabilized type of stainless steel which is immune to chromium carbide precipitation. Type 347 grades are thus recommended for parts fabricated by welding which cannot be subsequently annealed or for parts which must operate in service between 800 – 1600 °F.
Industry Uses /Products Turbine exhaust Collector, airplane exhaust stacks, jet engine parts, expansion joints, tubing, fasteners, flexible metal hose and bellows
UNS S34700
Specifications ASTM A240, ASME SA-240, AMS 5512

Material Properties

Density, ρ, lbs/in^3 0.288
Yield Strength, Sy, Psi 30,000
Tensile Strength, Su, Psi 75,000
Elongation % 40
Poisson’s Ratio, ν 0.30
Youngs Modulus, E psi 28000000
Coeff. Thermal Expansion, in/in/˚F 0.0000092
Melting Point, ˚F 2500 – 2550

Chemical Compostion, %

Carbon, C 0.08 (max)
Nickel, Ni 9.00 – 12.00
Chromium, Cr 17.00 – 19.00
Manganese, Mg 2.00 (max)

Alloy 20 (UNS: N08020)

Bellows Materials Alloy 20
Trade Name INCOLOY® alloy 20, Carpenter® 20 alloy, 20CB-3®
Description An austenitic stainless steel possessing excellent resistance to attack by sulfuric acid and many other aggressive environments.
Application Notes Alloy 20 stainless is also stabilized to limit inter-granular attack, even in the sensitized condition. Important advantages of alloy 20 stainless are its excellent mechanical properties and comparative ease of fabrication. The presence of Columbium in the alloy minimizes the precipitation of carbides during welding.
Industry Uses /Products Components for processing synthetic rubber processing. Components for processing gasoline, solvents, explosives, plastics, synthetic fibers, chemicals Food and dye production. Components for processing pharmaceutical
UNS N08020
Specifications ASTM A240, ASME SA-240

Material Properties

Density, ρ, lbs/in^3 0.292
Yield Strength, Sy, Psi 35,000
Tensile Strength, Su, Psi 80,000
Elongation % 30
Youngs Modulus, E psi 29000000
Coeff. Thermal Expansion, in/in/˚F 0.00000816