SS 310 Plate Composition: 310S Chemistry, Properties and High-Temperature Data

What Is SS 310 Plate?

SS 310 plate is a high-alloy austenitic stainless steel plate with nominally 25% chromium and 20% nickel. The fully austenitic structure gives it outstanding oxidation resistance and creep strength at elevated temperature, so 310 and its low-carbon version 310S (EN 1.4845) are specified for furnace components, heat exchangers, radiant tubes and heat treatment equipment rather than for ambient-temperature pressure duty.

The carbon content is the single most important variable in this family. Standard 310 allows up to 0.25% carbon, while 310S is capped at 0.08%, which reduces chromium carbide precipitation during welding and improves resistance to intergranular corrosion in the 500-800 C sensitisation range.

Chemical Composition of 310 and 310S Plate

Element	310 (%)	310S (%)
Cr	24.0 - 26.0	24.0 - 26.0
Ni	19.0 - 22.0	19.0 - 22.0
Si	0.75 max	0.75 max
Mn	2.00 max	2.00 max
C	0.25 max	0.08 max
P	0.045 max	0.045 max
S	0.030 max	0.030 max
Fe	Balance	Balance

Plate in this grade is normally supplied to ASTM A240, which covers the 310, 310S and 310H conditions, with equivalent JIS G4304 and EN 10088-2 designations available on request.

Physical Properties of 310S Plate

Property	Value
Density	8.0 g/cm3
Melting range	1402 - 1454 C
Thermal expansion, 20-100 C	16.3 x 10-6 /C
Thermal conductivity	14.2 W/m.K
Modulus of elasticity	193 GPa
Magnetic response	Non-magnetic in the annealed state

Mechanical Properties of 310S Plate

Property	Value
Tensile strength	515 - 655 MPa
0.2% yield strength	205 - 310 MPa
Elongation	40% min
Hardness	217 HBW max
Oxidation resistance, continuous	Up to 1050 C
Oxidation resistance, intermittent	Up to 1035 C

Variants of the 310 Family

310H: high-carbon version with 0.04-0.10% C, used for high-temperature strength and creep resistance above 800 C.

310S: low-carbon version (0.08% max) that resists carbide precipitation, so it is preferred whenever sections are welded.

310MoLN: molybdenum- and nitrogen-bearing variant designed for reducing environments such as urea and ammonium nitrate production, with better pitting and crevice resistance.

310Si: silicon-bearing heat-resistant variant for electric furnace parts, continuous casting equipment and glass furnace linings where a protective oxide scale must survive thermal cycling.

310L: commercial low-carbon variant with 0.03% C max, ordered for welded components that operate above 800 C and cannot be heat treated after fabrication.

310 versus 310S versus 304 at High Temperature

Grade	Carbon (%)	Continuous oxidation limit	Intermittent limit
310	0.25 max	1050 C	1035 C
310S	0.08 max	1050 C	1035 C
304	0.08 max	925 C	870 C

Both 310 and 310S keep a protective scale well above the 304 ceiling, and 310S adds substantially better weldability for the same high-temperature capability.

Frequently Asked Questions

Q: What is the composition of SS 310 plate?
Typically 24.0-26.0% chromium, 19.0-22.0% nickel, up to 2.00% manganese, up to 0.75% silicon and the balance iron, with carbon limited to 0.25% for 310 or 0.08% for 310S.

Q: What is the difference between 310 and 310S?
The carbon content. 310 permits up to 0.25% carbon while 310S is capped at 0.08%, which improves weldability and resistance to intergranular corrosion in the sensitisation range.

Q: Is 310S plate magnetic?
Fully annealed 310S is non-magnetic. Cold working or welding can generate a small amount of magnetic ferrite, which does not affect high-temperature performance.

Q: What is the density of 310S stainless steel?
About 8.0 g/cm3, so a 1 m by 2 m by 6 mm plate weighs roughly 96 kg.

Q: Which grade should be chosen for welded furnace parts?
310S or 310H. Choose 310S when sections are welded without a post-weld anneal, and 310H when creep strength above 800 C matters more than weldability.

Q: What finishes and thicknesses are available for 310S plate?
Hot-rolled and cold-rolled plate from about 0.3 mm to over 50 mm, supplied as No. 1, 2B, BA or polished finish, cut to size with mill test certificates issued per heat.