Therma 253 MA
EN 1.4835, ASTM UNS S30815

General characteristics

Therma 253 MA is a stainless steel with excellent oxidation and creep resistance in cyclic conditions that is best employed in temperatures up to 1150 °C/2100 °F. There is a slight susceptibility to embrittlement during continuous operation at 600–850 °C/1110–1560 °F.

Typical applications

  • Oil industry equipment
  • Conveyor belts
  • Refractory anchors
  • Expansion bellows
  • Radiant tubes, tube shields, and valves and flanges
  • Rotary kilns
  • Exhaust manifolds
  • Power generation applications
  • Cyclone dip tubes
  • Impact separators
  • Bell furnaces and muffle furnaces
  • Automotive components
  • Heat treatment trays
  • Dampers
  • Recuperator tubes for the steel industry
  • Large-scale bakery ovens
 

 

Product forms, available sizes and finishes

Flat

Product typeFinishesThicknessWidth
Black hot band1U4,50-12,70800-1600
Cold rolled coil2BB, 2C, 2D, 2E, 2G, 2J, 2R0,05-12,003-2040
Cold rolled sheet2BB, 2C, 2D, 2E, 2G, 2J, 2R0,50-6,00300-2040
Hot rolled coil, pickled1C, 1D, 1U2,50-10,0050-2040
Precision strip2R0,05-1,503-649
Quarto plate1D6,00-50,00400-3000

Long

Product typeFinishesThicknessWidth
Cast billet127,00-180,00127-180
Cast slab195,00-205,001000-1500
Cold drawn bar round6,00-25,406-25
Forged billet round200,00-230,00200-230
Forged billet square200,00-254,00200-254
Hot rolled / Black bar round75,00-230,0075-230
Peeled / turned bar round70,00-170,0070-170
Rolled billet round90,00-200,0090-200
Rolled billet square75,00-200,0075-200
Wire rod (Rod coil) round5,00-27,005-27
Chemical composition

The typical chemical composition for this grade is given in the table below, together with composition limits given for the product according to different standards. The required standard will be fully met as specified on the order.


The chemical composition is given as % by mass.

CMnCrNiMoNOther
Typical 0.0921.011.00.17Si:1.6 Ce:0.05
ASME II A SA-240 0.05-0.10≤0.8020.0-22.010.0-12.00.14-0.20Si:1.4-2.0 Ce:0.03-0.08
ASTM A240 0.05-0.10≤0.8020.0-22.010.0-12.00.14-0.20Si:1.40-2.00 Ce:0.03-0.08
EN 10095 0.05-0.12≤1.0020.00-22.0010.00-12.000.12-0.20Si:1.40-2.50 Ce:0.03-0.08
IS 6911 0.05-0.10≤0.8020.0-22.010.0-12.0≤0.700.14-0.20Si:1.40-2.00 Ce:0.03-0.08
Mechanical properties

The mechanical strength at elevated temperatures for Therma 253 MA are presented in the table below (minimum values).

º C 50 100 150 200 250 300 350 400 450 500 550 600 700
Rp0.2 [MPa] 280 230 198 185 176 170 165 160 155 150 145 140 130
Rm [MPa] 630 585 560 545 538 535 533 530 515 495 472 445 360

At higher temperatures, the creep strength is the dimensioning factor. Creep deformation strength and creep rupture strength for Therma 253 MA are presented in the table below. Values are according to EN 10095.

 

º C 500 550 600 650 700 750 800 850 900 950 1000 1050 1100
Creep rupture strength
Rkm,10 000 [MPa]
- 250 157 98 63 41 27 18 13 9.5 7 5.5 4
Creep rupture strength
Rkm, 100 000 [MPa]
- 160 88 55 35 22 15 11 8 5.5 4 3 2.3
Creep deformation strength
RA1,10 000 [MPa]
- 230 126 74 45 28 19 14 10 7 5 3.5 2.5
Creep deformation strength
RA1, 100 000 [MPa]
- 150 80 45 26 16 11 8 6 4.5 3 2 1.2

Mechanical properties at room temperature are shown in the table below.

StandardRp0.2Rp1.0RmElongationImpact strengthRockwellHBHV
 MPaMPaMPa%J
Product type: Cold rolled coil and sheet
Typical (thickness 1 mm)41545075065
ASME II A SA-240 ≥ 310 ≥ 600 ≤ 217
ASTM A240 ≥ 310 ≥ 600 ≤ 95HRB ≤ 217
EN 10095 ≥ 310 ≥ 350650-850 ≥ 40
IS 6911 ≥ 310 ≥ 600 ≤ 95HRB ≤ 217
Product type: Hot rolled coil and sheet
Typical (thickness 4 mm)
ASME II A SA-240 ≥ 310 ≥ 600 ≤ 217
ASTM A240 ≥ 310 ≥ 600 ≤ 217
EN 10095 ≥ 310 ≥ 350650-850 ≥ 40
IS 6911 ≥ 310 ≥ 600 ≤ 95HRB ≤ 217
Product type: Hot rolled quarto plate
Typical (thickness 15 mm)37041070050
ASME II A SA-240 ≥ 310 ≥ 600 ≤ 95HRB ≤ 217
ASTM A240 ≥ 310 ≥ 600 ≤ 95HRB ≤ 217
EN 10095 ≥ 310 ≥ 350650-850 ≥ 40
IS 6911 ≥ 310 ≥ 600 ≤ 95HRB ≤ 217
Product type: Wire rod
Typical37041070050

1)Elongation according to EN standard:
A80 for thickness below 3 mm.
A for thickness = 3 mm.
Elongation according to ASTM standard A2” or A50.

Corrosion resistance

Aqueous corrosion

Since most high-temperature materials are optimized with regard to strength and corrosion resistance at elevated temperatures, their resistance to electrochemical low-temperature corrosion may be less satisfactory. Components made of high-temperature material should therefore be designed and operated so that acid condensates are not formed, or at least so that any such condensates are drained away.

High-temperature corrosion

The resistance of a material to high-temperature corrosion is in many cases dependent on its ability to form a protective oxide layer. In a reducing atmosphere, when such a layer cannot be created (or maintained), the corrosion resistance of the material will be determined by its alloy content.

 

Oxidation

When a material is exposed to an oxidizing environment at elevated temperatures, a more or less protective oxide layer will be formed on its surface. Even if oxidation is seldom the primary cause of high-temperature corrosion failures, the oxidation behavior is important, because the properties of the oxide layer will determine the resistance to attack by other aggressive elements in the environment.The oxide growth rate increases with increasing temperature until the rate of oxidation becomes unacceptably high or until the oxide layer begins to crack and spall off, i.e. the scaling temperature is reached. The alloying elements that are most beneficial for oxidation resistance are chromium, silicon, and aluminum. A positive effect has also been achieved with small additions of so-called (re)active elements, e.g. yttrium, hafnium, and rare earth metals (REM, e.g. Ce and La). These affect the oxide growth so that the formed layer will be thinner, tougher, and more adherent, and thus more protective. This is especially beneficial in conditions with varying temperatures.

Pitting corrosion resistanceCrevice corrosion resistance
PRECPTCCT
24

PRE Pitting Resistant Equivalent calculated using the formula: PRE = %Cr + 3.3 x %Mo + 16 x %N
CPT Corrosion Pitting Temperature as measured in the Avesta Cell (ASTM G 150), in a 1M NaCl solution (35,000 ppm or mg/l chloride ions).
CCT Critical Crevice Corrosion Temperature is the critical crevice corrosion temperature which is obtained by laboratory tests according to ASTM G 48 Method F

Physical properties

Data according to EN 10088

 

DensityModulus of elasticityThermal exp. at 100 °CThermal conductivityThermal capacityElectrical resistanceMagnetizable
kg/dm3GPa10-6/°CW/m°CJ/kg°CµΩm
7.820017,0155000.85No
Fabrication

Like other austenitic steels, Therma 253 MA can also be formed in the cold condition. However, as a result of the relatively high nitrogen content, the mechanical strength is higher, and consequently greater deformation forces will be required.

Machining

The relatively high hardness of austenitic steels and their ability to strain harden must be taken into consideration in connection with machining. For more detailed data on machining, please contact Outokumpu.

Welding

Thrma 253 MA has very good weldability. To ensure weld metal properties (e.g. strength, corrosion resistance) equivalent to those of the parent metal, a filler material with a matching composition should preferably be used. In some cases, however, a differing composition may improve e.g. weldability or structural stability. Gas shielded welding has resulted in the best creep properties for welds. To facilitate the use of Therma 253 MA at the highest temperature range, TIG, plasma, or MAG processes should be used. Welding with MAG may require modern pulse equipment, and the use of special shielding gases containing Ar, He, and O2/CO2 to facilitate good arc stability and improved fluidity.

More detailed information concerning welding procedures can be obtained from the Outokumpu Welding Handbook, available from our sales offices.

Standards & approvals

The most commonly used international product standards are given in the table below.

 

StandardDesignation
ASME SA-240M Code Sect. II. Part AUNS S30815 / 253MA
ASTM A240/A240MUNS S30815 / 253MA
EN 100951.4835
IS 6911, AMENDMENT NO. 2ISS 308Ce