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Datasheet updated

2024-01-11 10:32
(supersedes all previous editions)

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Alleima® 353 MA is an austenitic chromium-nickel steel alloyed with nitrogen and rare earth metals. The grade is characterized by:

  • High creep strength
  • Very good resistance to isothermal and cyclic oxidation
  • Very good resistance to combustion gases
  • Very good resistance to carburization
  • Good resistance to nitriding gases
  • Good structural stability at high temperatures
  • Good weldability
  • Maximum operating temperature is approx. 1175°C (2150°F)

Trademark information: 353 MA is a trademark owned by Outokumpu OY.

Standards

  • UNS: S35315
  • EN Number: 1.4854

Product standards

  • ASTM A312
  • EN 10297-2

Chemical composition (nominal)

Chemical composition (nominal) %
C Si Mn P S Cr Ni N Ce*
0.07 1.6 1.5 ≤0.040 ≤0.015 25 35 0.16 0.05

* The quantity of other rare earth metals should be added to cerium, because the addition takes the form of misch metal containing about 50 % Ce.

Applications

The excellent oxidation and carburization resistance of Alleima® 353 MA in constantly carburizing gas, makes it particularly suitable grade for high-temperature petrochemical furnaces. The high nitriding resistance is very beneficial for service in high temperature cracked ammonia gas. Typical applications are:

  • Ethylene furnace, radiant cracking tubes
  • EDC furnace tubes
  • Tubes in wast heat recovery systems in the metallurgical industry, e.g. recuperators
  • Tubes in heat treatment furnaces, e.g. muffle tubes, radiant tubes, thermocouple protection tubes, burner components, furnace rollers
  • Recuperator tubes in chemical waste and sewage sludge incineration

Trademark information: 353 MA is a trademark owned by Outokumpu OY.

Corrosion resistance

Oxidation

Owing to the high silicon content and the addition of rare earth metals (REM), Alleima® 353 MA has very high resistance to oxidation. The REM addition also contributes to improved scale adhesion during temperature cycling. Figure 1, which shows the measured weight increase after 45 h cyclic oxidation at different temperatures, illustrates how Alleima® 353 MA compares with some other high temperature grades. Weight increase after longer exposure at 1150°C (2100°F) is shown in Figure 2. The weight increase shown in Figure 1 and Figure 2 includes the weight of any spalled oxide.


Figure 1. Weight increase for Alleima 353 MA and other grades after 45h oxidation.


Figure 2. Weight increase versus time during oxidation at 1150°C

Carburizing and nitrogen pick-up

Corrosion attack by carburization or nitrogen pick-up usually follows a parabolic rate law: x2=kp * t+C, where x is the attack, expressed as penetration depth or weight increase, kp a rate constant, t exposure time and C a constant accounting for the initial attack (which follows a different rate law).

Due to its ability to form a dense chromium oxide and its high nickel content, Alleima® 353 MA also has good resistance to carburization and nitrogen pick-up.

Figure 3 shows the measured rate constants for carburization tests of various alloys at different temperatures. Cyclically carburizing-oxidizing conditions are often more detrimental, but, as Figure 4 shows, Alleima® 353 MA is able to resist these conditions better than other alloys.

In nitrogen pick-up tests, Figure 5, Alleima® 353 MA showed similar resistance to Alloy 601.


Figure 3. Rate constant for total carburization; a<sub>c</sub>=1; PO<sub>2</sub>~0.


Figure 4. Rate constant for total carburization and carburizationoxidation. Carburization: 950°C(1740°F); a<sub>c</sub>=1; PO<sub>2</sub>~0. Oxidation: 1050°C(1920°F); a<sub>c</sub>~0; PO<sub>2</sub>=0.21atm.


Figure 5. Rate constant for nitrogen pick-up in cracked ammonia.

Sulphur attack

Alloys with high nickel content are generally sensitive to attack by sulphur at higher temperatures. However, under oxidizing conditions a protective oxide will be able to form, contributing to an improved resistance to sulphur attack. This is illustrated in Figure 6, which shows the rate constant for different alloys in different sulphidizing-oxidizing conditions. Again, the dense oxide formed on Alleima® 353 MA is shown to be advantageous.


Figure 6. Rate constant for sulphidation-oxidation.

Bending

Due to its higher strength compared with conventional stainless steels, higher deformation forces are required for cold bending of Alleima® 353 MA.

Annealing after cold bending is not normally necessary, but this decision should be made taking account of the degree of bending and the service conditions.

Forms of supply

Seamless tube and pipe in Alleima® 353 MA is supplied in dimensions up to 200 mm (7.9 in.) outside diameter in the solution-annealed and white pickled condition, or solution annealed by a bright-annealing process.

Other forms of supply

  • Bar steel

Heat treatment

Tubes are delivered in the heat treated condition. If another heat treatment is needed after further processing, the following is recommended:

Stress relieving

1000–1100°C (1830–2010°F), 10–15 minutes, cooling in air.

Solution annealing

1100–1200°C (2010–2190°F), 5–20 minutes, rapid cooling in air or water.

Mechanical properties

Metric units, at 20°C
Proof strength Tensile strength Elongation Hardness
Rp0.2 Rp1.0 Rm Aa) A2" Vickers
MPa MPa MPa % %
≥300 ≥340 ≥650 ≥40 ≥35 ≈160

1 MPa = 1 N/mm2
a) A is based on an original gauge length of 5.65 √S0.

Imperial units, at 68°F
Proof strength Tensile strength Elongation Hardness
Rp0.2 Rp1.0 Rm Aa) A2" Vickers
ksi ksi ksi % %
≥44 ≥49 ≥94 ≥40 ≥35 ≈160

a) A is based on an original gauge length of 5.65 √S0.

At high temperatures

Metric units
Temperature Proof strength
Tensile strength
Rp0.2 Rp1.0 Rm
°C MPa MPa MPa
100 ≥228 ≥261 ≥536
200 ≥195 ≥223 ≥498
300 ≥166 ≥190 ≥470
400 ≥152 ≥173 ≥444
500 ≥143 ≥163 ≥437
600 ≥138 ≥159 ≥422
Imperial units
Temperature Proof strength Tensile strength
Rp0.2 Rp1.0 Rm
°F ksi ksi ksi
200 ≥33 ≥38 ≥78
400 ≥28 ≥32 ≥71
600 ≥23 ≥27 ≥68
800 ≥21 ≥24 ≥63
1000 ≥20 ≥23 ≥62
1100 ≥20 ≥23 ≥61

Rp0.2 and Rp1.0 correspond to 0.2 % offset and 1.0% offset yield strength, respectively.

Creep strength (average values)

Metric units
Temperature, °C Creep strength 1% Creep rupture strength
10 000 h 100 000 h 10 000 h 100 000 h
MPa MPa MPa MPa
550 149 86 206 129
600 88 52 127 80
650 54 33 82 52
700 35 21 56 36
750 22 14 39 25
800 15 9.7 28 18
850 10.5 6.9 20 14
900 8 5.1 15 10
950 6 3.9 11 6.7
1000 4.5 3.0 8 4.8
1050 3.5 2.3 6 3.5
1100 2.7 1.8 4.5 2.9
Imperial units
Temperature, °F Creep strength 1% Creep rupture strength
10 000 h 100 000 h 10 000 h 100 000 h
ksi ksi ksi ksi
1100 16.5 9.5 23.2 14.7
1200 8.0 4.9 12.0 7.5
1300 4.8 3.0 7.8 5.1
1400 3.0 1.9 5.4 3.4
1500 1.9 1.3 3.6 2.5
1600 1.4 0.9 2.6 1.7
1700 1.0 0.6 1.9 1.2
1800 0.7 0.5 1.3 0.8
1900 0.5 0.4 0.9 0.5
2000 0.4 0.3 0.7 0.4
Proof strength Tensile strength Elongation Hardness Vickers
Rp0.2 Rp1.0 Rm Aa) A2"
MPa ksi MPa ksi MPa ksi % %
min. min. min. min. min. min. min. min. approx.
300 44 340 49 650 94 40 35 160

1 MPa = 1 N/mm2
a) A is based on an original gauge length of 5.65 √S0.

Physical properties

Density: 7.9 g/cm3, 0.28 lb/in3

Thermal conductivity
Temperature, °C
W/m °C
Temperature, °F
Btu/ft h °F
20 11 68 6.5
100 13 200 7.5
200 15 400 8.5
300 17 600 10
400 18 800 11
500 20 1000 12
600 22 1200 13
700 23 1400 14
800 25 1600 15
900 26 1800 15.5
1000 27 2000 16
1100 29
Specific heat capacity
Temperature, °C
J/kg °C
Temperature, °F
Btu/ft h °F
20 480 68 0.11
100 500 200 0.12
200 530 400 0.13
300 555 600 0.13
400 575 800 0.14
500 590 1000 0.14
600 610 1200 0.15
700 625 1400 0.15
800 640 1600 0.16
900 655 1800 0.16
1000 665 2000 0.16
1100 680
Thermal expansion1)
Temperature, °C
Per °C
Temperature, °F
Per °F
20-100 15.5 68-200 8.5
20-200 15.5 68-400 8.5
20-400 16.5 68-800 9
20-600 17 68-1000 9.5
20-700 17 68-1200 9.5
20-800 17.5 68-1400 9.5
20-900 18 68-1600 10
20-1000 18 68-1800 10
20-1100 18.5 68-2000 10.5

1) (x10-6)

Modulus of elasticity1)
Temperature, °C
MPa
Temperature, °F
ksi
20 190 68 27.5
200 180 400 26
400 165 800 23.5
600 155 1000 23
700 150 1200 22
800 140 1400 20.5
900 135 1600 20
1000 130 1800 19
1100 125 2000 18

1) (x103)

Resistivity
Temperature, °C
μΩm
Temperature, °F
μΩin.
20 1.00 68 39
200 1.07 400 42
400 1.14 800 45
600 1.20 1000 47
700 1.22 1200 48
800 1.25 1400 49
900 1.28 1600 50
1000 1.30 1800 51
1100 1.32 2000 52

Welding

The weldability of Alleima® 353 MA is good. Suitable methods of fusion welding are manual metal-arc welding (MMA/SMAW) and gas-shielded arc welding, with the TIG/GTAW method as first choice.

In common with all fully austenitic stainless steels, Alleima® 353 MA has low thermal conductivity and high thermal expansion. Welding plans should therefore be carefully selected in advance, so that distortions of the welded joint are minimized. If residual stresses are a concern, solution annealing can be performed after welding.

For Alleima® 353 MA, heat-input of <1.0 kJ/mm and interpass temperature of <100°C (210°F) are recommended.

Recommended filler metals

TIG/GTAW or MIG/GMAW welding

ISO 18274 S Ni 6082/AWS A5.14 ERNiCr-3 (e.g. Exaton Ni72HP)

MMA/SMAW welding

ISO 14172 E Ni 6182/AWS A5.11 ENiCrFe-3 (e.g. Exaton Ni71)

Disclaimer: Recommendations are for guidance only, and the suitability of a material for a specific application can be confirmed only when we know the actual service conditions. Continuous development may necessitate changes in technical data without notice. This datasheet is only valid for Alleima materials.