1.4833 Forgings X12CrNi23-13, the European heat resisting grade close to AISI 309S. Forged rings, flanges, shafts, discs, tube sheets and bars.

The point that causes most order errors on this grade is that 1.4833 and 309S are not the same specification. Carbon and sulphur differ, and the two limits pull in opposite directions.

Shaded rows are the three limits that differ. A heat aimed at 1.4833 can carry more carbon than 309S permits, and a heat aimed at 309S can carry twice the sulphur that 1.4833 permits. If the order has to satisfy both, say so at enquiry stage and the melt is aimed at the overlap: C max 0.08, S max 0.015, Ni 12.0 to 14.0.

1.4833 resists the effects of hot gases and products of combustion at temperatures above 550 C, and 1000 C is its highest application temperature in air. Resistance to sulphur bearing gases is low, in both reducing and oxidising conditions, and one published figure puts the usable ceiling in a sulphur bearing environment at around 900 C. Against nitrogenous and oxygen deficient gases, and against carburisation, resistance is moderate rather than high. Sources differ on this last point: one supplier datasheet describes the grade as resistant to carburising, nitriding and carbonitriding atmospheres, while the DIN EN 10095:2018-12 material data rates that resistance as medium. For a carburising furnace application, treat it as medium and qualify by trial.

Embrittlement in the 750 to 800 C band

Held in the 750 to 800 C range, the structure tends towards a two phase condition and sigma phase separates out. Impact strength falls as a result. This is a design input, not a defect: parts that will be thermally cycled or impact loaded through that band should be sized on aged properties. Where that is unacceptable, move up to 1.4845 or to a nickel base alloy such as Incoloy 800H.

Room temperature values in the solution annealed condition, +AT. EN 10095 covers rolled and drawn product forms, so for forgings the acceptance values are agreed at order stage and tested on the forging itself.

Creep limit and creep rupture strength

Read alongside the temperature table: the grade is rated to 1000 C for scaling resistance, but at 900 C it carries only 3 MPa for 100,000 hours. Oxidation resistance and load carrying capacity run out at very different temperatures, and the lower of the two governs the design.

1.4833 is melted here on the electric arc furnace route: EF, then ladle refining, then vacuum oxygen decarburisation where carbon and nitrogen need tight control. Maximum heat size is 60 tonnes. The grade does not need a remelting step, which is why it sits at the short end of the 20 to 60 day lead time band.

Forging is carried out on 6,300 t, 4,000 t and 2,000 t hydraulic open-die presses, with 5 t, 3 t, 2 t, 1 t and 750 kg hammers for drawing out and small batch work. Rings are rolled on 6 m, 3 m and 1 m radial-axial mills. Published hot working practice for the 309S type starts near 1120 to 1177 C with reheating above roughly 980 C, and sources give slightly different windows, so the schedule is fixed against the governing specification before the ingot is cut.

After forging the parts are solution annealed and cooled rapidly. Published practice for this grade is 1050 to 1150 C, and 1000 to 1150 C followed by rapid quench is the recommendation given for the 309S type after hot forming. Fourteen heat treatment furnaces are on site, including three high temperature car bottom furnaces and two well furnaces 15,000 mm deep for vertical quenching of long shafts. The steel is tough and ductile, so machining is slow: allow generous stock and expect lower cutting speeds than on 304.

Forged rings and seamless rolled rings, including contoured rings and gear ring blanks. Forged flanges, weld neck, blind, slip-on and long weld neck. Forged round bars, flat bars and blocks. Forged discs and tube sheets for heat exchangers and covers. Forged shafts, spindles and rolls. Forged sleeves, bushings and bored cylinders. Forged nozzles and hollow sections. Each is forged from a single piece of steel melted on site, with no welding and no casting.

Where the grade is used

The service profile points at industrial furnace construction and thermal processing hardware: annealing boxes and covers, burner components, furnace doors and fans, muffles and retorts, recuperators, walking beams, salt bath crucibles, and parts of chemical process apparatus running at elevated temperature. Forgings are specified over castings in these positions where the part must pass volumetric inspection or carry load at temperature. Note what the grade is not for. 1.4833 is a dry heat grade, and carbon up to 0.15 % leaves it sensitisation prone, so it is the wrong choice for wet corrosive or polythionic acid service. For those duties use 321H, 347H, 904L or a nickel alloy.

Compositions behind these designations are not identical. GOST 20Ch23N13 and BS 309S24 both allow wider nickel ranges than EN 1.4833, and BS 309S24 runs 13.0 to 16.0 % Ni. Nominate one governing specification on the purchase order and treat the rest as reference.

Chemistry is verified at the furnace by optical emission spectrometry to ASTM E415 and by infrared carbon and sulphur analysis to ASTM E1019, with handheld PMI available on the finished part. Mechanical testing runs on 600 kN and 300 kN universal machines to ASTM A370, with Charpy V-notch impact testing to minus 60 C. Ultrasonic testing is to ASTM A388 or EN 10228-3, magnetic particle to ASTM E709 where applicable, and grain size to ASTM E112. Intergranular corrosion testing to ASTM A262 is placed with an accredited third party laboratory and the report is issued with the mill certificate.

Documents are issued as EN 10204 3.1 mill test certificates, or EN 10204 3.2 witnessed by BV, DNV, LR, SGS, TUV or your own inspector. The works holds CCS, BV, DNV, LR and NK class approvals. Because the steel is melted in house, traceability runs from the melt number through forging, heat treatment and machining to shipment.

Is 1.4833 the same as AISI 309S?

Close, but not interchangeable. 1.4833 allows up to 0.15 % C and 12.0 to 14.0 % Ni with S max 0.015 %. 309S caps carbon at 0.08 % and allows 12 to 15 % Ni with S max 0.030 %. Neither certificate automatically satisfies the other. Specify both if you need dual certification.

What is the maximum service temperature?

1000 C in air is the highest application temperature, with the application range starting at 550 C. Around 900 C in sulphur bearing gases. About 700 C where creep governs on a loaded part.

Does it become brittle in service?

Service around 750 to 800 C brings sigma phase precipitation and a two phase structure, and impact strength drops. Design loaded or cycled parts on aged properties.

How are the forgings heat treated?

Solution annealed and rapidly cooled, 1050 to 1150 C by published practice for this grade, with 1000 to 1150 C plus rapid quench given for the 309S type after hot forming. Fourteen furnaces on site, including two 15 m well furnaces for vertical quenching.

Can you supply one piece?

Yes. Minimum order is 10 kg with no minimum piece count, so a single prototype ring or one shaft is quotable. Small parts are usually grouped into a furnace batch, which is why quantity still affects unit price.

Is it weldable?

Yes, by all welding methods, and it is used in industrial furnace construction. Where the weldment sees wet corrosive service rather than dry heat, the low carbon 309S variant is the safer specification.

What does 1.4833 cost compared with 310S?

Lower, because nickel content is roughly 12 to 14 % against 19 to 22 % for 1.4845, and nickel dominates the alloy cost. Where 1000 C is enough, 1.4833 is the cheaper answer. Prices move with the nickel market, so quotations are valid for a stated period.

Six items give a firm price without a round trip, usually within two working days.

Customer audits, pre-shipment inspection and third party witness testing are welcome. Wuxi Shuofang International Airport is 30 km from the plant and Shanghai airports are 160 km. Arrange visits by email so an English speaking engineer is available.

For higher temperatures, more nickel or wet corrosion resistance:

• AISI 330
• AISI 321H
• AISI 347H
• A182 F321
• 904L
• Incoloy 800H
• Incoloy 800HT
• Inconel 601
• All stainless grades
• All product forms