310S — high Cr-Ni austenitic stainless for high temperature service to 1100 C. For furnace parts, annealing boxes, heat treatment equipment and burner nozzles.
Standards
| Standard Body |
Designation |
Country |
| EN |
X12CrNi25-21 / 1.4845 |
EU |
| AISI/SAE |
310S |
USA |
| ASTM |
A240 / A276 Type 310S |
USA |
| UNS |
S31008 |
USA |
| JIS |
SUS310S |
Japan |
| GOST |
20H23N18 (20Kh23N18) |
Russia |
| BS EN |
310S31 |
UK |
| JUS |
C.4592 |
Yugoslavia |
Composition (wt.%)
| Element |
Symbol |
Min % |
Max % |
Typical % |
| Carbon |
C |
— |
0.080 |
0.040 |
| Silicon |
Si |
— |
1.500 |
0.700 |
| Manganese |
Mn |
— |
2.000 |
1.200 |
| Chromium |
Cr |
24.000 |
26.000 |
25.000 |
| Nickel |
Ni |
19.000 |
22.000 |
21.000 |
Physical
Melting Range
1380 – 1420
°C
Thermal Conductivity
14.2
W/mK
Thermal Expansion
15.9
×10⁻⁶/K
Machinability
| Rating |
38.0% (B1112=100%) |
| Turning HSS |
16.0 m/min |
| Turning Carbide |
82.0 m/min |
| Surface Finish |
Ra 0.4-1.6 um |
| Coolant |
High-pressure flood coolant mandatory |
Mechanical
| Condition |
Rm (MPa) | Re (MPa) | A (%) |
HB | HRC | KV (J) | E (GPa) |
| Solution Annealed (+AT) |
≥515 |
≥205 |
≥30 |
≤217 |
— |
— |
200 |
Heat Treatment
| Process |
Temperature |
Medium |
Duration |
Hardness After |
| Solution Annealing |
1040 – 1150°C |
Water quench |
Sufficient |
<=HB 217 |
Applications
Heat Treatment Equipment: Furnace retorts, annealing boxes, radiant tubes, muffle furnaces and conveyor belts.
Petrochemical: Ethylene cracker tubes, reformer furnace components and high-temperature reactors.
Power Generation: Superheater supports and components in coal-fired power stations.
Notes
vs 309S: 310S: 25%Cr+21%Ni — highest oxidation resistance of standard grades; service to 1100 C. 309S: 23%Cr+13%Ni — lower cost, service to 980 C. Use 310S when temperature exceeds 980 C or sulphur-bearing atmospheres.
Sigma Phase: Prolonged exposure at 600-900 C causes brittle sigma phase. Parts must not be impact loaded after high-temperature service without reconditioning.