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Austenitic SS 253 MA

Austenitic SS 253 MA

UNS S30815 (253 MA,1.4835) Stainless Steel | X9CrNiSiNCe21-11-2.

Austenitic SS 253 MA is a stainless-steel compound consisting of nickel & chromium with adequate amounts of nitrogen and other reactive alloying elements. The grade retains its strength under various environments and at elevated temperatures. It is heat resistant and retains its heat resistance properties due to its microstructure.

It is specifically used for its exceptional oxidation resistance properties under different conditions. The addition of silicon provides the grade with oxidation resistance at high and low temperatures whilst the cerium addition in small amounts resists oxidation at elevated temperatures. Hence, these micro-alloying elements prove to be constructive in improving the oxide scale of the base metal.

Nitrogen in combination with molybdenum helps in localized corrosion resistance as well as increases strength, it also helps in delaying carbide precipitation during sigma phase. Nitrogen along with carbon provides creep rupture strength. When compared to 300-series alloys like 321H, 310S, 304H, the grade 253 shows higher strength to resist creep. The 300-series alloy’s creep rupture strength varies with temperature while the grade 253 remains constant in strength.

The grade can be readily used in thermally active environments with a longer service life. The ductility and the forming characteristics of the grade 253 also prove to be lucrative. These features attract many applications for the grade. Thinner sections requiring adequate strength can be suitably manufactured using this grade. The grade can be hot and cold formed. Pertaining to the nitrogen content and the mechanical strength, large forces are required for the grade to form.

The grade due to its high strength is used in respective structural as well as pressure bearing applications. Its strength is exceptionally retained at higher temperatures and hence, the grade is readily selected for applications in the temperature range of 500-950°C. The alloy also has convenient aqueous corrosion resistance. During sigma phase, the grade might face a slight sensitization but the strength is restored with a little loss of aqueous corrosion resistance. An excellent performance of the grade is achieved under environments with iso-thermal, cyclic oxidation, flue gases, combustion gases, and carburizing conditions. With the addition of nitrogen and adequate amount of carbon, the grade is less prone to sigma phase embrittlement. It exceptionally retains its structural stability.

  • Chemical composition
  • Physical properties
  • General data
  • Standards Specifications
  • Forms of Supply
  • Corrosion Resistance
  • Heat Treatment
  • Weldability
  • Machining
  • Applications
  • Possible grade alternatives
Grade   Ni C Cr Mn Si P Ce S N
253 MA Min. 10.0 0.05 20.0 - 1.10 - 0.03 - 0.14
Max. 12.0 0.10 22.0 0.80 2.00 0.040 0.08 0.030 0.20
Density kg/m3) 7800
Melting Point  
Specific Heat 0-100°C ( J/kg.K) 500
Thermal Conductivity at 20°C (W/m.K) 15.0
Elastic Modulus (GPa) 200
Electrical Resistivity (nW.m) 850
Magnetic Permeability 1.01
Poisson Ratio 0.31
Standard 253 MA
UNS S 30815
WERKSTOFF NR. 1.4835
EN X9CrNiSiNCe21-11-2
SS 2368
AFNOR  
JIS  
Pipes & Tubes
Summary Standards
Standard Specification for Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes ASTM A213
Standard Specification for Welded Austenitic Steel Boiler, Superheater, Heat-Exchanger, and Condenser Tubes ASTM A249
Standard Specification for Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes ASTM A312
Standard Specification for Electric-Fusion-Welded Austenitic Chromium-Nickel Stainless Steel Pipe for High-Temperature Service and General Applications ASTM A358
Fittings & Flanges
Summary Standards
Standard Specification for Forged or Rolled Alloy and Stainless Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service ASTM A182

Pipes and tubes

The stainless steel 253 basically depends on the formation of the oxide layer on the base metal. The micro-alloying elements in the grade help in the formation of an exceptional oxide layer. There is initially a formation of chromium oxide on the base metal. With the addition of silicon, the layer becomes thicker with silicon dioxide and an addition of cerium in small quantity makes the oxide layer adherent. This formation improves the overall resistance to oxidation, corrosion, erosion and thermal load cycles. An exceptional oxidation resistance up to 1100°C can be provided.

The oxide layer in any metal break after a certain point due to the growth in stress. The slow growth of the oxide becomes beneficial in this case since the layer will be retained for a longer period. Under cyclic oxidation conditions, at 1000°C and 165 cycles, the grade when compared to grades like 310S, 309S, 153 MA, has the lowest weight gain (mg/ m^2).

The grade in tube or pipe form is delivered in a heat-treated condition. If further processing is done, solution annealing and stress relief annealing are the better options. The metal is normally exposed to high temperatures during service. If at all heat treatment is required, even after cold or hot working, solution annealing or stress relieving is performed.

Solution annealing is performed around 1050-1200°C, for 10-20 minutes, followed by rapid quenching in air or water. Stress relieving is performed around 850-1000°C for 10-15 minutes followed by air cooling. Solution annealing after cold working can be done to retain the creep resistance properties.

The grade can be readily welded using common fusion methods. Shielded metal welding, tungsten inert gas and metal inert gas, submerged arc welding are common techniques to weld the metal. The grade is normally used at elevated temperatures. Welding after its use in such conditions should be taken care of. The oxide layer should be properly removed. Heat input should be kept low due to its high thermal expansion. Pre-heat and post-heat are normally not required. Filler metals of equivalent grades should be used.

The grade has fine strength and hardness. It is also susceptible to strain hardening. Sharp and rigid tooling, adequate lubrication, heavy feeds, slow speeds and powerful machinery are recommended.

Furnace tubes for mud incineration plants, EDC cracking tubes, Stack dampers, Muffle tubes in continuous wire annealing furnaces, Petrochemical and refinery tube hangers, Burners, Boiler Nozzles, Tubes in waste heat recovery systems in the metallurgical industry, Tubes in heat treatment furnaces, Tubing for fluidized-bed combustion plants, Expansion Bellow, Styrene reactor tubes, Tubes for carbon black process gas coolers/air heaters, Tubes for the glass and cement industries, Convection tubes, electric heater elements, hoods, flues.

Grade 310
Grade   Ni C Cr Mn Si P S N
310 Min. 19.0 - 24.0 - - - - -
Max. 22.0 0.25 26.0 2.0 1.50 0.045 0.030 0.10
Grade 304H
Grade   Ni C Cr Mn Si P S N
304H Min. 8.0 0.04 18.0 - - - - -
Max. 10.5 0.10 20.0 2.0 0.75 0.045 0.030 -
Grade Hastelloy C276
Grade   Ni C Co Mn Si Cr W S V Fe P Mo
Hastelloy C276 Min. Bal(50.99) - - - - 14.5 3.0 - - 4.0 - 15.0
Max. - 0.010 2.5 1.00 0.08 16.5 4.5 - 0.35 7.0 0.04 17.0

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