What heat treatment is applied to Z12CN25-20 forgings?

Supersaturation, also called solution treatment, at 1100-1150 C followed by water quenching. The grade is austenitic and is not precipitation hardenable, so no ageing step is applied. Forging and rolling are carried out between 1150 C and 950 C.

What is the maximum service temperature of Z12CN25-20?

About 1050 C in air and oxidising atmospheres. In reducing gases carrying sulphur compounds in higher concentrations the limit falls to about 900 C, and reaches about 1000 C where sulphur impurities are small.

Which forged shapes are available in Z12CN25-20?

Jiangyin Jiangnan Metal Co., Ltd. supplies Z12CN25-20 as open-die forged rings, seamless rolled rings, flanges, round bars, shafts, discs, blanks, sleeves, bushings, forged tubes, tube sheets, valve bodies, valve seat rings and nozzles, made to customer drawing.

Who supplies Z12CN25-20 open-die forgings?

Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. Telephone +86-189-2135-9659, email sales@steelforgepieces.com. Every item is made to order against a drawing, so pricing is quoted per enquiry.

Home › Stainless Steel › Z12CN25-20

Z12CN25-20 Forgings — 25Cr-20Ni Heat-Resistant Steel

Q: What is Z12CN25-20 steel?

Z12CN25-20 is the AFNOR designation for a 25% chromium / 20% nickel austenitic heat-resistant stainless steel, specified at max 0.15% C, 23.0-26.0% Cr and 18.0-21.0% Ni. It resists scaling in air and oxidising atmospheres up to about 1050 C.

Q: Is Z12CN25-20 the same as 310S?

The two are close but not identical. Z12CN25-20 allows up to 0.15% carbon with 23.0-26.0% Cr and 18.0-21.0% Ni, while AISI 310S (UNS S31008) is limited to 0.08% carbon with 24.0-26.0% Cr and 19.0-22.0% Ni. Because of the wider carbon range, Z12CN25-20 is also cross-referenced to AISI 310H. Confirm the governing standard before ordering.

AFNOR Z12CN25-20, close equivalent of 1.4845 / X12CrNi25-21 / AISI 310S / UNS S31008

Z12CN25-20, also written Z12CN25.20 or Z 12 CN 25-20, is the AFNOR designation for a 25% chromium / 20% nickel austenitic heat-resistant stainless steel, specified at max 0.15% C, 23.0–26.0% Cr and 18.0–21.0% Ni. It resists scaling in air and oxidising atmospheres up to about 1050 C and is a close equivalent of EN 1.4845 / X12CrNi25-21 and AISI 310S.

Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory in Jiangyin, Jiangsu, China, produces this grade as forged rings, seamless rolled rings, flanges, shafts, round bars, discs, sleeves, bushings, forged tubes and tube sheets to customer drawing, with EN 10204 3.1 or 3.2 certification. Every item is made to order, so price and lead time are quoted against your drawing.

Grade family: Austenitic Cr-Ni
Nominal: 25Cr · 20Ni
Air service: to 1050 C
Tensile Rm: 500–700 MPa
Yield Re: min 210 MPa
Hardness: max 192 HB

Equivalent grades and cross-reference

Z12CN25-20 belongs to the international 25Cr-20Ni heat-resistant family. The table compares the specified chemistry of each designation rather than listing them as interchangeable, because the carbon limits differ and that difference affects code compliance.

Specified composition, % by mass. Data from the Virgamet grade cross-reference for 1.4845 / AISI 310S.
Standard	Designation	C max	Cr	Ni	Mn max	Si max	P max	S max
AFNOR	Z12CN25-20	0.15	23.0–26.0	18.0–21.0	2.0	1.0	0.040	0.030
EN / SEW	X8CrNi25-21, X12CrNi25-21, 1.4845	0.10	24.0–26.0	19.0–22.0	2.0	1.5	0.045	0.015
ASTM / AISI	310S, UNS S31008	0.08	24.0–26.0	19.0–22.0	2.0	1.5	0.045	0.030
DIN	X16CrNi25-20, 1.4843	0.20	22.0–25.0	19.0–22.0	2.0	Si 1.5–2.5	0.045	0.030
BS	310S24	0.15	23.0–26.0	19.0–22.0	2.0	1.0	0.045	0.030
GOST	20Kh23N18	0.20	22.0–25.0	17.0–20.0	2.0	1.0	0.035	0.020
PN	H23N18	0.20	22.0–25.0	17.0–20.0	1.5	1.0	0.045	0.030

Further designations covering the same family: Z8CN25-20, Z12CN26-21, X6CrNi25-20 (1.4951), X22CrNi25-20, CSN / STN 17255, SUS 310S, F-331, 12NiCr250, 06Cr25Ni20, 0Cr25Ni20, tube grades TP310S and TP310H, UNS S31009, and the aerospace specifications AMS 5521, 5572, 5577, 5651, 7490.

Check before ordering. Z12CN25-20 permits up to 0.15% carbon, roughly double the 0.08% ceiling of AISI 310S. For that reason the grade is also cross-referenced to the higher-carbon AISI 310H. Higher carbon raises creep strength but lowers resistance to intergranular attack after sensitisation. Tell us which standard governs the part, ASTM 310S, ASTM 310H, EN 1.4845 or AFNOR, and we melt to that window.

Mechanical and physical properties

Figures below are room-temperature values for the supersaturated condition of 1.4845 / AISI 310S. Properties of a finished forging depend on section size, reduction ratio and test location, all agreed at order stage and reported on the EN 10204 certificate.

Room-temperature properties, supersaturated condition. Data from Virgamet (1.4845) and the Tachart datasheet for X12CrNi25-21.
Property	Value
Tensile strength, R_m	500–700 MPa (Tachart quotes an upper bound of 750 MPa)
Yield point, R_e	min 210 MPa
Elongation, A	min 33% (Tachart: 35%)
Hardness	max 192 HB
Modulus of elasticity, E	196 GPa
Thermal capacity, c_p 20–100 C	500 J/kg·K
Linear expansion coefficient	15.0 × 10^-6 K^-1
Thermal conductivity	14.7 W/m·K

Creep limit and creep strength

This creep behaviour is the reason the grade is chosen for load-carrying furnace internals instead of a 304 or 321 type.

Values in MPa. R1 = creep limit, Rz = creep strength, for the stated number of hours. Data from Virgamet, 1.4845 / X8CrNi25-21.
Property	600 C	700 C	800 C	900 C
Creep limit R1/1 000 h	100	45	18	10
Creep limit R1/10 000 h	90	30	10	4
Creep strength Rz/1 000 h	170	80	35	15
Creep strength Rz/10 000 h	130	40	18	8.5
Creep strength Rz/100 000 h	80	18	7	3

Service temperature and atmosphere

The grade is classified as heat-resistant under EN 10095 and SEW 470.

Air and oxidising atmosphere: up to about 1050 C.
Reducing gases with sulphur compounds in higher concentrations: about 900 C.
Reducing gases with small sulphur impurities: about 1000 C.

Classification as heat-resistant does not restrict the material to high-temperature duty. A large share of demand comes from buyers who want the acid resistance of this chemistry in chemical apparatus for gas pyrolysis, hydrogenation and methane conversion, where heat resistance and acid resistance are needed at the same time.

Forging, heat treatment and welding

Hot working

Forging and rolling are carried out between 1150 C and 950 C. Hot bending of sheet components is done at 900–950 C.

Heat treatment

Supersaturation at 1100–1150 C followed by water quenching. The grade is fully austenitic and is not precipitation hardenable, so no ageing or precipitation-hardening step applies.

Welding

Products in this grade are normally arc welded with matching 24-18 type electrodes of the ES-24-18 class. Filler and procedure should be qualified against the fabrication code that governs the project.

Melting and testing

We melt the grade by EAF + VOD, with ESR remelting available where cleanliness or segregation control calls for it. Forgings are ultrasonically tested to EN 10228-3, SEP 1921 or ASTM A388 as specified, and supplied with EN 10204 3.1 mill certification or EN 10204 3.2 third-party certification.

Forged products in Z12CN25-20

All shapes are produced open-die to customer drawing or dimension list, as single pieces or in series.

Forged rings
Seamless rolled rings
Flanges
Shafts
Eccentric shafts and crankshafts
Round bars
Discs and disks
Blanks
Sleeves
Bushings
Forged tubes and pipes
Tube sheets
Valve bodies and blocks
Valve stems
Valve seat rings
Nozzles
Gears and spindles
Forged wheels
Manifolds

Typical applications

Industry or unit	Forged components
Fluidised bed furnaces, coal combustors	Rolled rings, shafts, grids, piping, wind boxes
Ore processing and steel plants	Smelter and steel melting equipment, continuous casting equipment
Pressure vessels, shell and tube heat exchangers	Shafts, pipes, forged tubes, tube sheets, flanges, air receivers
Columns, towers, tanks, silos	Shafts, flanges, rings, pipes, process modules, preheaters
Petroleum refining	Sleeves, discs, catalytic recovery systems, flares, recuperators, tube hangers
Fluid catalytic cracking units	Open-die forgings and nozzles, polythionic acid service
Sintering and cement plants	Burners, burner shields, feeding and discharging systems, wind boxes
Thermal processing	Annealing covers and boxes, burner grids, doors, fans, muffles, retorts, recuperators, walking beams
Oil and gas wellhead	Wellhead and Christmas tree parts, crystalliser equipment
Food processing and cryogenics	Forged wheels, manifolds, cryogenic structures

Questions we are asked most often

Is Z12CN25-20 the same as 310S?

Close, but not identical. Z12CN25-20 allows up to 0.15% C with 23.0–26.0% Cr and 18.0–21.0% Ni. AISI 310S (UNS S31008) is capped at 0.08% C with 24.0–26.0% Cr and 19.0–22.0% Ni. Because of the wider carbon range, Z12CN25-20 is also cross-referenced to AISI 310H.

What heat treatment do the forgings receive?

Supersaturation at 1100–1150 C with water quench. No ageing, since the grade is austenitic and cannot be precipitation hardened.

What is the maximum operating temperature?

About 1050 C in air and oxidising atmospheres, about 900 C in reducing gases carrying higher concentrations of sulphur compounds, about 1000 C where sulphur impurities are small.

What is the largest ring or shaft you can forge in this grade?

It depends on the shape and the reduction ratio required. Send the drawing, or OD x ID x height for rings and diameter x length for shafts, and we confirm feasibility, weight and lead time.

What certification comes with the material?

EN 10204 3.1 mill test certificate as standard, EN 10204 3.2 third-party certificate on request. Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388 at the acceptance class you specify.

How is the price decided?

There is no list price. Each piece is forged to a drawing, so cost depends on grade, finished weight, input billet size, heat treatment, machining allowance, NDT class and quantity. Send the drawing and we quote.

What do you need in order to quote?

Grade or the equivalent designation you work to, drawing or finished dimensions with machining allowance, quantity, heat treatment and NDT requirements, certificate type, and destination port.

Ask for a Z12CN25-20 quotation

Send a drawing or your dimensions for rings, flanges, shafts, bars, discs, sleeves or tube sheets. We normally reply within one working day.

sales@steelforgepieces.com +86-189-2135-9659 Contact page

Technical data on this page is compiled from published grade cross-references for 1.4845 / AISI 310S. Values are typical and given for guidance; they are not a guarantee of properties for a specific forging. Order-specific results are stated on the EN 10204 certificate.
Published by Jiangyin Jiangnan Metal Co., Ltd., open-die forging factory, Jiangyin, Jiangsu, China. Last reviewed 11 October 2026.