310S16 Forgings, BS 1501-3 / 1.4845 / AISI 310S Heat Resisting Stainless Steel

What 310S16 is

310S16 comes from BS 1501-3, the British specification for steels for pressure purposes covering corrosion and heat resisting plate, sheet and strip. The designation identifies a fully austenitic chromium-nickel steel, and the chromium and nickel levels define what it is for. At 23 to 26 percent chromium the steel forms an adherent, self-repairing oxide scale that stays put at temperatures where ordinary 18/8 austenitic grades have started to spall. At 19 to 22 percent nickel the austenite is stable enough to take repeated heating and cooling through that range without transforming.

Carbon is held to 0.08 percent maximum, and that figure is what separates this grade from its high carbon sibling. Lower carbon means less chromium carbide available to precipitate at grain boundaries, so the steel keeps more of its corrosion resistance and toughness after time at temperature. The trade is slightly lower creep strength than the high carbon 310H variant, which is the grade to specify when sustained load at temperature matters more than ductility after service.

Buyers reach for 310S16 when a part has to live inside a furnace. Oxidation resistance and thermal stability are what it is bought for, not strength and not general purpose corrosion resistance. It carries a high alloy cost, since roughly 45 percent of the steel by weight is chromium and nickel. Specifying it where a cheaper 309S or 321H would serve is a common and expensive mistake, and one this works raises at enquiry rather than quoting quietly.

Equivalent grades and cross-references

310S16 appears under many designations, because most national systems standardised the same 25/20 chromium-nickel chemistry. The table gives the cross-references in regular commercial use. An equivalent means comparable composition and comparable typical properties, not an identical specification, since limits on silicon, nitrogen and residuals differ between systems. Name the governing standard on the purchase order so the melt is aimed at the right window.

If a drawing calls a grade not listed here, send it across. Most 25/20 chromium-nickel specifications can be satisfied from one melt with an agreed chemistry restriction, and the certificate can be dual marked where both standards are genuinely met.

Chemical composition of 310S16

Limits in weight percent, balance iron. Ladle analysis and product analysis are both reported on the mill certificate against the heat number.

Where an order is placed against 1.4845 or X8CrNi25-21 rather than the British designation, the aim chemistry shifts to the European limits: carbon 0.10 percent max, silicon 1.50 percent max, manganese 2.00 percent max, phosphorus 0.045 percent max, sulphur 0.015 percent max, chromium 24.0 to 26.0 percent, nickel 19.0 to 22.0 percent and nitrogen 0.11 percent max. The tighter sulphur and the permitted nitrogen are the practical differences, and both are controlled at the melt rather than corrected later. Restricted residual aims are accepted where a specification calls for them. State the requirement at enquiry so it goes into the melt instruction.

Mechanical and physical data

310S16 is supplied solution annealed and is not hardenable, so there is no strength range to select by tempering. The figures below are indicative room temperature values for the grade in its 1.4845 form. The low yield to tensile ratio and the high elongation are characteristic of fully austenitic steels and are the reason the grade takes thermal cycling well. Acceptance is governed by the values agreed at order and certified for the heat and section supplied.

Two of these figures affect design directly. Thermal conductivity at 14.7 W/(m.K) is low, roughly a third that of plain carbon steel, so thick 310S16 sections heat and cool slowly and develop steeper internal gradients. Expansion at 15.0 x 10^-6/K is high, around 30 percent above a ferritic stainless. A 310S16 part in a cycling furnace therefore generates real thermal stress, so clearances, restraint and support design are worth attention at the drawing stage.

Creep data

For parts carrying load at temperature, creep governs rather than room temperature strength. Indicative creep values for 1.4845 in MPa:

Load bearing capacity falls by about an order of magnitude between 600 C and 900 C, so a design stress that is comfortable at 600 C becomes a rupture risk at 900 C. Where sustained load and high temperature occur together, state the design life and this works will advise whether 310S16, the higher carbon 310H or a nickel base alloy such as Incoloy 800HT is the better answer.

Service temperature and its limits

In air, 310S16 and 1.4845 resist scaling up to about 1050 C in continuous service. Intermittent service is rated slightly lower, around 1035 C, because thermal cycling cracks and reforms the oxide scale and consumes chromium each time. Above this range the grade is at the end of its useful life and a higher silicon steel such as 1.4841 or AISI 314 is the recommended replacement.

Atmosphere changes the answer substantially, and this is where specifications most often go wrong. In reducing gases, and in atmospheres carrying sulphur compounds at meaningful concentration, the practical limit drops to roughly 900 C. Where sulphur is present only as a minor impurity, about 1000 C is workable. Nickel rich austenitic steels are vulnerable to sulphidation, so a nickel content of 19 to 22 percent that is an asset in air becomes a liability in a sulphur bearing reducing atmosphere. A stated peak temperature with no stated atmosphere is not enough to confirm a grade, so both are requested at enquiry.

One further caution applies. Published work on AISI 310S type steel reports measurable microstructural change after exposure in the 600 to 800 C band, through carbide and sigma phase precipitation, affecting both toughness and corrosion resistance. A part that passes through that band on the way to 1000 C is generally fine. A part that sits in it for thousands of hours needs review before the forging is cut.

Melting and forging

310S16 is melted in an electric arc furnace and refined by vacuum oxygen decarburisation. That route is what makes 0.08 percent maximum carbon achievable at 23 to 26 percent chromium, since decarburising under vacuum shifts the carbon-chromium equilibrium so carbon can be removed without stripping chromium into the slag. Electroslag remelting is added where the order calls for tighter cleanliness, lower centreline segregation and better transverse properties.

Hot working runs between 1150 C and 950 C. The lower limit is not advisory. Austenitic steels of this type work harden steeply, and forging below about 950 C risks tearing and leaves residual stress that no later anneal fully removes. The narrow window, together with the high hot strength of the grade, is why 310S16 needs more press capacity per kilogram than a carbon steel of the same size, and why experience with the grade shows up in the yield.

• EAF plus VOD as the standard melting route for 310S16 forgings
• ESR available for large rings, pressure retaining parts and critical rotating furnace components
• Open-die forging on hydraulic presses, forged from the ingot rather than cut from rolled bar
• Seamless ring rolling for rings and flanges, giving continuous circumferential grain flow
• Forging reduction ratio agreed at order and recorded on the certificate
• Grain flow follows the part contour, which gives better fatigue and creep performance than machining from plate

Grain direction is the practical argument for forging this grade rather than cutting it from plate. A furnace ring machined from plate has grain running straight through the hoop direction, while a seamless rolled ring has it running around the circumference, which is the direction the thermal hoop stress acts.

Heat treatment

310S16 is austenitic. It does not transform to martensite, it contains no precipitation hardening elements, and it cannot be hardened by quenching, tempering or ageing. It is supplied solution annealed, and the only route to higher strength is cold work. A specification calling for a solution and age cycle on this grade is in error, and Jiangyin Jiangnan Metal raises the query before the order enters production rather than certifying against an impossible requirement.

The water quench after solution annealing does specific work. It carries the section through the sensitisation range fast enough that chromium carbides have no time to precipitate at grain boundaries, and slow cooling from solution temperature undoes the anneal. In very heavy sections the quench rate at the core is inevitably lower than at the surface, which is a section size question worth discussing at enquiry for thick discs and blocks. Every furnace charge is recorded with time, temperature and quench medium on the heat treatment chart supplied with the certificate.

Forged product forms in 310S16

Everything below is forged to drawing. Shapes not shown are quoted on the same basis, so send the drawing.

Size and weight range

The limit for any given part depends on its shape, on the forging reduction ratio required, and for 310S16 on the press load the grade demands in its narrow hot working window. Treat the table as a starting point and confirm the specific piece.

Testing and certification

Every 310S16 forging leaves the works with a certificate tying the part back to its heat number, its heat treatment charge and its test results.

Non-destructive testing

• Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388, to the quality class named on the order
• Dye penetrant inspection for surface examination. Magnetic particle inspection does not apply, because solution annealed 310S16 is non-magnetic
• Hardness survey across the section
• Dimensional inspection against the drawing

Destructive and chemical testing

• Tensile, impact and hardness testing on prolongations or sacrificial coupons
• Chemical analysis by spectrometer, ladle and product analysis both reported
• Intergranular corrosion testing to ASTM A262 or the specification called up, the meaningful check on a low carbon heat resisting austenitic
• Grain size, macro-etch and non-metallic inclusion rating on request
• Elevated temperature tensile testing by agreement where the duty warrants it

Documentation

• EN 10204 3.1 inspection certificate as standard
• EN 10204 3.2 certificate countersigned by SGS, BV, TUV or Lloyds on request
• Heat treatment charts, UT reports and dimensional reports issued with the goods
• Third party witness inspection accepted at the works

Where 310S16 is used

Classification as a heat resisting steel does not confine the grade to hot service. Its chromium content also gives good resistance to oxidising acids, and many buyers specify it as a corrosion resisting steel where heat and corrosive attack occur together, which in process plant they usually do.

How to order 310S16 forgings

An enquiry is quoted fastest when it carries what the works needs to plan the ingot, the press and the furnace. A drawing is ideal, and rough dimensions are enough to start.

• Drawing, or rough dimensions with machining allowance
• Quantity, and whether repeat orders are expected
• Grade and governing standard: 310S16 to BS, 1.4845 to EN, AISI 310S to ASTM, or SUS 310S to JIS
• Service temperature and atmosphere, which together decide whether this grade is the right one
• Melting route, if ESR is required
• NDT scope and acceptance class
• Certificate type, EN 10204 3.1 or 3.2, and any third party witness
• Destination port and required delivery date

Quotation is normally returned within 24 hours. Production lead time runs 15 to 45 days depending on size, heat treatment and testing scope.

sales@steelforgepieces.com +86 189 2135 9659

Questions and answers about 310S16

What is 310S16 stainless steel?

310S16 is a British Standard designation for a heat resisting austenitic chromium-nickel stainless steel, taken from BS 1501-3, the specification for corrosion and heat resisting steels for pressure purposes. Its composition limits are carbon 0.08 percent max, silicon 1.00 percent max, manganese 2.00 percent max, phosphorus 0.045 percent max, sulphur 0.025 percent max, chromium 23.00 to 26.00 percent and nickel 19.00 to 22.00 percent. The chromium and nickel content gives resistance to scaling in air to about 1050 C, which is why the grade is specified for furnace and high temperature plant components. Jiangyin Jiangnan Metal Co., Ltd. forges 310S16 to drawing.

What is 310S16 equivalent to?

310S16 cross-references to the European material number 1.4845 and the chemical names X8CrNi25-21 and X12CrNi25-21, to AISI 310S and UNS S31008 in the American system, to SUS 310S in Japan, to Z8CN25-20 in the French system, to GOST 20Kh23N18 and to Swedish 2361. Within the British system, 310S24 and 310S31 cover the same chromium-nickel family at slightly different carbon and silicon levels. Equivalence means comparable chemistry and comparable typical properties, not an identical specification, so Jiangyin Jiangnan Metal asks buyers to name the governing standard and the acceptance criteria on the purchase order.

Is 310S16 a JIS grade?

No. 310S16 is a British Standard designation from BS 1501-3, not a Japanese one. The Japanese equivalent of this grade is SUS 310S under JIS. Jiangyin Jiangnan Metal can certify forgings to the British designation 310S16, to the European 1.4845 or X8CrNi25-21, to the American AISI 310S or UNS S31008, or to JIS SUS 310S, according to which standard the buyer names on the order.

What is the maximum service temperature of 310S16?

310S16 and its equivalent 1.4845 resist scaling in air up to about 1050 C in continuous service. Intermittent service is usually rated slightly lower, around 1035 C, because thermal cycling is harder on the oxide scale. Above that range a higher silicon grade such as 1.4841 or AISI 314 is normally recommended instead. In reducing atmospheres, and in atmospheres carrying sulphur compounds, the useful limit drops to roughly 900 C, or about 1000 C where sulphur is present only as a minor impurity. Atmosphere matters as much as temperature, so Jiangyin Jiangnan Metal asks for the service gas as well as the peak temperature at enquiry.

Can 310S16 be hardened by heat treatment?

No. 310S16 is a fully austenitic stainless steel. It contains no precipitation hardening elements and does not transform to martensite, so it cannot be hardened by quenching, tempering or ageing. It is supplied solution annealed, typically from 1100 to 1150 C with a water quench for 1.4845, and it is strengthened only by cold work. A specification calling for a solution and age cycle on this grade should be queried, and Jiangyin Jiangnan Metal raises it before the order goes into production.

What is the chemical composition of 310S16?

The 310S16 composition to BS 1501-3 supplied by Jiangyin Jiangnan Metal is carbon 0.08 percent max, silicon 1.00 percent max, manganese 2.00 percent max, phosphorus 0.045 percent max, sulphur 0.025 percent max, chromium 23.00 to 26.00 percent and nickel 19.00 to 22.00 percent, balance iron. Where the order is placed against 1.4845 or X8CrNi25-21 instead, the aim chemistry is adjusted to those limits, which permit up to 1.5 percent silicon and up to 0.11 percent nitrogen over a chromium range of 24.0 to 26.0 percent and a nickel range of 19.0 to 22.0 percent. Ladle analysis and product analysis are both reported on the mill certificate against the heat number.

What are the mechanical properties of 310S16 forgings?

In the solution annealed condition the grade in its 1.4845 form shows tensile strength of roughly 500 to 700 MPa, yield point above about 210 MPa, elongation above about 33 percent, modulus of elasticity near 196 GPa and hardness below about 192 HB. Austenitic grades of this type have a low yield to tensile ratio and high ductility, which is what makes them tolerant of thermal cycling. Actual values depend on section size and test position. The values that govern acceptance are those agreed at order and certified on the test report for the specific heat and section.

Which forged shapes can you make in 310S16?

Jiangyin Jiangnan Metal produces 310S16 as forged round, square and flat bars, shafts and spindles, hollow bars, sleeves, bushings, cylinders, barrels, casings and shells, forged rings and seamless rolled rings, flanges, discs, disks and blocks, tube sheets, nozzles, rolls and rollers, and valve components including stems, seat rings, bodies and bonnets. Parts are forged to drawing, so shapes outside this list are quoted on the same basis. Send the drawing or the rough dimensions with machining allowance.

What size and weight of 310S16 forging can you produce?

Jiangyin Jiangnan Metal forges 310S16 in single pieces from about 50 kg to 20 tonnes. Round bars and shafts run from 80 to 1200 mm diameter and up to 8000 mm long, hollow bars and sleeves from 200 to 2000 mm outside diameter with a 100 mm minimum bore, rings and seamless rolled rings up to about 3000 mm outside diameter and 1000 mm height, and discs and blocks up to about 2500 mm diameter and 800 mm thick. The practical limit for any given part depends on its shape and on the forging reduction ratio required, so send the drawing for confirmation.

Which melting route is used for 310S16 forgings?

310S16 is melted by electric arc furnace with vacuum oxygen decarburisation, the EAF plus VOD route. That route makes it possible to hold carbon to 0.08 percent maximum at 23 to 26 percent chromium without losing chromium to the slag. Electroslag remelting is offered where the order calls for tighter cleanliness, reduced centreline segregation and better transverse properties, which is the usual choice for large rings, heavily loaded rotating furnace parts and pressure retaining components.

Where is 310S16 used?

310S16 is used for mechanically loaded parts working at high temperature: furnace components and casings, retorts, muffles, annealing covers, radiant tubes, saggers, kiln and oven linings, conveyor belts, rollers, fans, hooks, stands and trolleys for heat treatment plant, crucibles, and parts of chemical apparatus for gas pyrolysis, hydrogenation and methane conversion. Its heat resistance comes with good resistance to oxidising acids, so it is also bought as a corrosion resisting steel where hot and corrosive duty occur together, for example in petroleum refining and in heat exchanger and pressure vessel internals.

Is there anything to watch out for with 310S16 in service?

Yes. Long exposure in the 600 to 800 C range causes microstructural change in AISI 310S type steels through carbide and sigma phase precipitation, which reduces toughness and can reduce corrosion resistance. Parts intended to sit for long periods in that band should be reviewed rather than assumed acceptable. Sulphur bearing and reducing atmospheres also lower the safe temperature substantially. Jiangyin Jiangnan Metal reviews the intended duty against the grade before accepting an order and says plainly if a different grade suits the application better.

What non-destructive testing do you carry out on 310S16 forgings?

310S16 forgings are ultrasonically tested to EN 10228-3, SEP 1921 or ASTM A388, to the quality class stated on the order. Dye penetrant inspection is used for surface examination, since solution annealed 310S16 is non-magnetic and magnetic particle inspection does not apply. Hardness survey, tensile and impact testing, chemical analysis, grain size, intergranular corrosion testing to the specification called up, and dimensional inspection are carried out as required, and all results are issued on the certificate.

What certificates are issued with 310S16 forgings?

Jiangyin Jiangnan Metal issues an EN 10204 3.1 inspection certificate as standard, and an EN 10204 3.2 certificate countersigned by a third party such as SGS, BV, TUV or Lloyds when the order requires it. The certificate covers heat number, ladle and product chemical analysis, the heat treatment record, mechanical test results, non-destructive testing results and dimensional results. Third party witness inspection is accepted at the works.

How do I get a price for a 310S16 forging?

Send the drawing or the rough dimensions with machining allowance, the quantity, the governing standard, the service temperature and atmosphere, and the testing and certification you need to sales@steelforgepieces.com, or call +86 189 2135 9659. Jiangyin Jiangnan Metal Co., Ltd. is at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. Quotation is normally returned within 24 hours, and production lead time runs 15 to 45 days depending on size, heat treatment and testing scope.

Related stainless steel grades

Grades commonly compared with or substituted for 310S16 at this works:

• AISI 321H, titanium stabilised, lower alloy cost, for moderate high temperature duty
• AISI 330, higher nickel, better carburisation resistance in furnace atmospheres
• Incoloy 800H and Incoloy 800HT, where creep strength above 800 C governs
• Incoloy DS, high silicon, for more severe oxidising service
• Alloy 45TM and Alloy 602, nickel base grades above the reach of 310S16
• 904L, where aqueous corrosion rather than heat is the governing duty

See the full stainless steel forging grade list or all forged product forms.

About the supplier

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. The works forges bars, shafts, hollow bars, sleeves, seamless rolled rings, discs and blocks in carbon steel, alloy steel, tool steel, stainless steel and nickel alloys, supplying furnace, heat treatment plant, petrochemical, power generation, valve, oil and gas and general engineering customers worldwide. 310S16 is one of the heat resisting austenitic stainless grades held as a regular forging item.

Contact: +86 189 2135 9659, sales@steelforgepieces.com