253MA is a grade combining excellent service properties at high temperatures with ease of fabrication. It resists oxidation at temperatures up to 1150°C and can provide superior service to Grade 310 in carbon, nitrogen and sulphur containing atmospheres.
Another proprietary designation covering this grade is 2111HTR.
253MA contains fairly low nickel content, which gives it some advantage in reducing sulphide atmospheres when compared to high nickel alloys and to Grade 310. The inclusion of high silicon, nitrogen and cerium contents gives the steel good oxide stability, high elevated temperature strength and excellent resistance to sigma phase precipitation.
The austenitic structure gives this grade excellent toughness, even down to cryogenic temperatures.
Chemical Composition
| Element | Percentage |
| C | 0.05 – 0.1 |
| Cr | 20 – 22 |
| Ni | 10 – 12 |
| N | 0.14 – 0.2 |
| Ce | 0.03 – 0.08 |
| Mn | < 0.8 |
| Si | 1.1 – 2.0 |
| P | < 0.04 |
| S | < 0.03 |
| Fe | Balance |
Key Properties
These properties are specified for flat rolled product (plate, sheet and coil) as Grade S30815 in ASTM A240/A240M. Similar but not necessarily identical properties are specified for other products such as pipe and bar in their respective specifications.
Composition
Typical compositional ranges for grade 253MA stainless steels are given in table 1.
Table 1. Composition ranges for 253MA grade stainless steel
C | Mn | Si | P | S | Cr | Ni | N | Ce | |
| min. | 0.05 | – | 1.10 | – | – | 20.0 | 10.0 | 0.14 | 0.03 |
| max. | 0.10 | 0.80 | 2.00 | 0.040 | 0.030 | 22.0 | 12.0 | 0.20 | 0.08 |
Mechanical Properties
Typical mechanical properties for grade 253MA stainless steels are given in table 2.
Table 2. Mechanical properties of 253MA grade stainless steel
Tensile Str (MPa) min | Yield Str 0.2% Proof (MPa) min | Elongation (% in 50mm) min | Hardness | |
Rockwell B (HR B) max | Brinell (HB) max | |||
600 | 310 | 40 | 95 | 217 |
Physical Properties
Typical physical properties for grade 253MA stainless steels are given in table 3.
Table 3. Physical properties of 253MA grade stainless steel
Density (kg/m3) | Elastic Modulus (GPa) | Mean Coefficient of Thermal Expansion (mm/m/°C) | Thermal Conductivity (W/m.K) | Specific Heat | Electrical Resistivity (nW.m) | |||
0-100°C | 0-600°C | 0-1000°C | at 20°C | at 1000°C | ||||
7800 | 200 | 17.0 | 18.5 | 19.5 | 15.0 | 29.0 | 500 | 850 |
Grade Specification Comparison
Approximate grade comparisons for 253MA stainless steels are given in table 4.
Table 4. Grade specifications for 253MA grade stainless steel
UNS No | Old British | Euronorm | Swedish SS | Japanese JIS | |||
BS | En | No | Name | ||||
S30815 | – | – | 1.4835 | X9CrNiSiNCe21-11-2 | 2368 | – | |
| These comparisons are approximate only. The list is intended as a comparison of functionally similar materials not as a schedule of contractual equivalents. If exact equivalents are needed original specifications must be consulted. | |||||||
Possible Alternative Grades
Possible alternative grades to grade 253MA stainless steels are given in table 5.
Table 5. Possible alternative grades to 253MA grade stainless steel
Grade | Why it might be chosen instead of 253MA |
310 | Carburising atmospheres require a higher nickel content |
304H | Lower cost alternative, provided the operating temperature is below about 800°C |
Nickel Alloys | Carburising atmospheres or temperatures above the 1100 – 1150°C maximum of 253MA. |
Corrosion Resistance
Heat Resistance
Oxidation – excellent resistance to air, at temperatures up to 1150°C. At high temperatures the steel quickly forms a thin, highly adherent and elastic oxide. This oxide gives good protection even under cyclic conditions.
Carburisation – Under oxidising conditions this grade can perform well, but alloys with higher nickel content are preferred if the atmosphere is reducing.
Sulphidation – good resistance to sulphur-bearing gases in an oxidising atmosphere, even if only traces of oxygen are present. Reducing gases prevent the protective oxide forming.
253MA has high strength at elevated temperatures so is often used for structural and pressure-containing applications at temperatures above about 500°C and up to about 900°C. Its strength at these temperatures is higher than that of alternatives such as Grade 310.
253MA will become sensitised in the temperature range of 425-860°C; this is not a problem for high temperature applications, but will result in reduced aqueous corrosion resistance.
Heat Treatment
Solution Treatment (Annealing) – Heat to 1050-1150°C and cool rapidly. It is recommended that the material be solution treated after 10-20% cold work to achieve maximum creep strength in service.
This grade cannot be hardened by thermal treatment.
Welding
Excellent weldability by all standard fusion methods, using matching filler metals. AS 1554.6 pre-qualifies welding of 253MA with Grade 22.12HT rods or electrodes. Grade 309 fillers can be used if lower creep strength can be tolerated. Pure argon shielding gas should be used.
Machining
As for other austenitic stainless steels, the machining requires sharp tools, slow speeds and heavy feed. This grade has a low sulphur content.
Applications
Typical applications include:
- Furnace components including burners, retorts, conveyor belts, fans, jigs and baskets, rollers, walking beams, radiant tubes, electric heater elements, refractory anchors, hoods, flues, grates, expansion bellows.
- Petrochemical and refinery tube hangers.