C28Mn is a manganese steel for quenching and tempering. It is written 28Mn6 in EN 10083-2 and carries the material number 1.1170. The composition is 0.25–0.32 % carbon with 1.30–1.65 % manganese, and manganese supplies the hardenability, so the grade reaches medium strength without chromium, molybdenum or nickel additions.
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 C28Mn to customer drawings as shafts, seamless rolled rings, discs, sleeves, hollow bars, blocks, flange blanks and bars, in diameters from 100 mm to 6000 mm and single-piece weights from 10 kg to 15,000 kg, supplied normalised or quenched and tempered with an EN 10204 3.1 inspection certificate.
- EN designation
- 28Mn6also written C28Mn
- Material number
- 1.1170W.Nr. / DIN
- Standard
- EN 10083-2quenching and tempering steels
- Type
- Manganese steelnon-alloy quality grade
- Tensile, +N, ≤16 mm
- 630 MPa540 MPa at 500–1000 mm
- Yield, +N, ≤16 mm
- 345 MPa260 MPa at 500–1000 mm
- Forging range
- 1100–850 °Cslow cool after forging
- Certification
- EN 10204 3.13.2 on request
What is C28Mn steel?
C28Mn is classified as a non-alloy quality steel for quenching and tempering. The designation gives the composition: about 0.28 % carbon, with manganese as the deliberate addition. European practice writes the same steel as 28Mn6 under material number 1.1170. The C-prefixed form still appears on older drawings and on purchase specifications written outside Europe, and Jiangyin Jiangnan Metal Co., Ltd. accepts orders under either designation.
The grade is specified where a shaft, ring or disc has to come out of temper in the region of 700 to 900 MPa, the ruling section is moderate, and the cost of chromium and molybdenum is not justified. Manganese at 1.30–1.65 % raises hardenability sufficiently to through-harden moderate sections in oil or water.
Is C28Mn an alloy steel or a carbon steel?
C28Mn is a carbon steel. Chromium, molybdenum and nickel appear only as residual limits, and the sum Cr + Mo + Ni is capped at 0.63 %, which keeps the grade below the alloy-steel threshold. It is commonly catalogued alongside alloy steels, on this site included, because buyers consider it against 42CrMo4 and AISI 4140 for the same components.
C28Mn or 42CrMo4?
The choice follows the ruling section. Up to about 100 mm ruling section, C28Mn quenches and tempers to serviceable properties at a lower material cost. Above that, manganese alone no longer carries hardenability to the core, the centre of the forging tempers soft, and 42CrMo4 or 34CrNiMo6 is the correct specification. Jiangyin Jiangnan Metal Co., Ltd. raises this at enquiry stage, before material is committed.
C28Mn chemical composition
The limits below are applied by Jiangyin Jiangnan Metal Co., Ltd. to all C28Mn forging stock. Heat analysis is verified before billet is released to the forge.
| Element | Minimum | Maximum | Function in the steel |
|---|---|---|---|
| Carbon (C) | 0.25 | 0.32 | Determines attainable hardness and tempered strength |
| Manganese (Mn) | 1.30 | 1.65 | Principal addition; supplies hardenability and fixes sulfur as manganese sulfide |
| Silicon (Si) | – | 0.40 | Deoxidiser, with some solid-solution strengthening |
| Chromium (Cr) | – | 0.40 | Residual limit only |
| Nickel (Ni) | – | 0.40 | Residual limit only |
| Molybdenum (Mo) | – | 0.10 | Residual limit only |
| Phosphorus (P) | – | 0.030 | Restricted; contributes to temper embrittlement |
| Sulfur (S) | – | 0.035 | Restricted for hot workability and transverse ductility |
| Cr + Mo + Ni | – | 0.63 | Combined residual cap that keeps the grade non-alloy |
Values are nominal. Where a purchase specification narrows a limit, the purchase specification applies.
C28Mn mechanical properties
C28Mn is section-sensitive. Manganese is the only hardenability addition, so strength falls as the ruling section increases and a single tensile figure for the grade is of limited use. The tables below give properties by nominal thickness in the normalised condition.
| Nominal thickness | to 16 mm | 16–100 mm | 100–250 mm | 250–500 mm | 500–1000 mm |
|---|---|---|---|---|---|
| Rm tensile strength | 630 | 600 | 570 | 540 | 540 |
| Nominal thickness | to 16 mm | 16–100 mm | 100–250 mm | 250–500 mm | 500–1000 mm |
|---|---|---|---|---|---|
| Re upper yield / Rp0.2 proof strength | 345 | 310 | 290 | 270 | 260 |
| Nominal thickness | to 16 mm | 16–100 mm | 100–250 mm |
|---|---|---|---|
| A minimum elongation | 17 | 18 | 18 |
| Property | Condition | Value |
|---|---|---|
| KV impact energy at +20 °C | Quenched and tempered (+QT) | 40 J |
| Brinell hardness | Treated for cold shearability (+S) | max. 255 HBW |
| Brinell hardness | Soft annealed (+A) | max. 223 HBW |
Tensile strength in the quenched and tempered condition typically falls between 640 MPa and 930 MPa, depending on ruling section and tempering temperature. Properties in the +QT condition are agreed per order and confirmed on test pieces taken from the forging.
Forging and heat-treatment temperatures for C28Mn
Most C28Mn forging rejections originate in temperature control rather than in composition. Jiangyin Jiangnan Metal Co., Ltd. instruments each of the bands below, and the chart records are issued with the certificate.
| Operation | Temperature | Cooling | Notes |
|---|---|---|---|
| Forging / hot working | 1100–850 °C | Slow cool in sand or furnace | Overheat-sensitive near the top of the range; working below 850 °C causes cracking |
| Normalising | 850–890 °C | Air | Refines as-forged grain and evens properties through the section |
| Soft annealing | 650–700 °C | Furnace | Reduces hardness to 223 HBW maximum for machining or cold work |
| Hardening | 830–870 °C | Water or oil quench | Quench medium selected by section; water carries a cracking risk on complex shapes |
| Tempering | 540–680 °C | Air | Sets final strength; tempering low in the range trades toughness for hardness |
C28Mn equivalent grades
This steel is ordered under at least six designations. Jiangyin Jiangnan Metal Co., Ltd. accepts purchase orders under any of them and issues a material test certificate listing every designation the heat satisfies.
| Standard / country | Designation | Match |
|---|---|---|
| EN 10083-2 (Europe) | 28Mn6, also written C28Mn | Same grade |
| Werkstoff number | 1.1170 | Same grade |
| DIN (Germany) | 28Mn6 | Same grade |
| SAE / AISI (USA) | 1330 | Equivalent |
| UNS (USA) | G13300 | Equivalent |
| BS 970 (UK) | 150M28 | Equivalent |
| AFNOR (France) | 20M5 | Equivalent |
| JIS (Japan) | SMn433 | Nearest |
| GB/T (China) | 30Mn2 | Nearest |
Cross-references match on chemistry. They do not match on delivery condition, testing scope or acceptance criteria. Where a drawing names a standard, that standard governs. An equivalence table is a starting point for enquiry and is not an approval to substitute.
What C28Mn forgings does Jiangyin Jiangnan Metal produce?
Jiangyin Jiangnan Metal Co., Ltd. operates an open-die forging works at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, employing approximately 460 people including 9 senior engineers and 32 intermediate engineers. Demand for C28Mn is dominated by one-off and small-batch heavy sections, for which closed-die tooling does not pay back, so the grade is worked open-die.
| Parameter | Range | Note |
|---|---|---|
| Diameter | 100 – 6000 mm | Across all grades worked at the plant |
| Length | 100 – 12000 mm | Shafts and drawn sections |
| Single-piece weight | 10 – 15000 kg | Finished forging weight |
| Hydraulic press | 4500 t | Main open-die press |
| Forging hammers | 1 t / 3 t / 6 t / 9 t | Four hammers for smaller sections |
| Ring rolling mills | 3 m and 6 m | Seamless rolled rings |
| Heat treatment | Normalise, anneal, harden and temper | In-house, instrumented and chart-recorded |
| Certification | EN 10204 3.1 / 3.2 | 3.2 witnessed by a third party on request |
Product forms produced in C28Mn are forged shafts, discs and blocks, seamless rolled rings, forged rings, sleeves, bushings and hollow bars, flange blanks, tube sheets, round, square, flat and hexagonal forged bars, gear and pinion shaft blanks, cylinders, hubs and housings.
Delivery condition is normalised as standard, or quenched and tempered to an agreed strength class. Parts are supplied as-forged, rough machined with an agreed allowance, or finish machined to drawing.
How is a C28Mn forging produced?
The route below is the standard sequence used by Jiangyin Jiangnan Metal Co., Ltd. The stages run in this order because each one depends on the last.
- Billet sourcing and verification C28Mn billet is received with the mill certificate and the heat analysis is verified before release to the forge. Manganese content is checked against the 1.30–1.65 % band, since hardenability in the finished part depends on it.
- Preheat and soak The billet is through-heated to 1100 °C and held until core and surface temperatures equalise. Overheating coarsens the grain irreversibly, so furnace temperature is capped.
- Upsetting The billet is upset under the press to break down the cast dendritic structure. A forging ratio of at least 3:1 is targeted so that the finished section carries worked grain.
- Drawing, punching, expanding The piece is drawn down for a shaft, or punched and expanded over a saddle mandrel for rings and sleeves. Seamless rolled rings are transferred to the 3 m or 6 m ring mill.
- Controlled reheats The forging returns to the furnace as often as required so that all deformation finishes above 850 °C. Continuing to work a cooling piece is the most frequent cause of cracking in C28Mn.
- Slow cool After the final blow the forging is cooled slowly in sand or in the furnace. At heavier sections C28Mn hardens readily in still air, and an uncontrolled cool introduces stress into a part that has not yet been machined.
- Heat treatment Normalising at 850–890 °C, or hardening at 830–870 °C with a water or oil quench followed by tempering at 540–680 °C. Charge position, soak time and quench delay are logged.
- Rough machining and non-destructive testing The forging is rough machined to a testable surface and ultrasonically inspected to EN 10228-3 or ASTM A388 against the acceptance class stated on the order. Magnetic particle inspection to EN 10228-1 is carried out where surface examination is specified.
- Testing and certification Heat chemistry, tensile and yield strength, elongation, reduction of area, impact energy and hardness are recorded on an EN 10204 3.1 inspection certificate, together with heat-treatment chart records.
Where are C28Mn forgings used?
| Industry | Service | Forged components |
|---|---|---|
| General machinery | Medium-duty rotating and reciprocating parts | Shafts, couplings, lever arms, connecting rods |
| Mining and construction | Crane and excavator drives, crusher assemblies | Axles, journals, pinion shaft blanks, ring gears |
| Wind energy | Nacelle and yaw assemblies | Rolled ring blanks, flange blanks, bearing housings |
| Hydraulics | Cylinder and press assemblies | Cylinder bodies, sleeves, gland nuts, piston rods |
| Marine and offshore | Deck machinery, winches, fairleads | Shafts, sheave hubs, blocks, heavy fasteners |
| Pressure equipment | Moderate and lower-temperature vessel parts | Nozzle forgings, flange blanks, tube sheets |
Welding, machining and common problems
Welding and preheat
C28Mn has acceptable weldability, which places it below the readily weldable low-carbon grades. At 0.25–0.32 % carbon and up to 1.65 % manganese the carbon equivalent is high enough for cold cracking, so normal practice is preheat above about 200 °C, low-hydrogen consumables, controlled interpass temperature and slow cooling. Post-weld heat treatment is usual on thick or restrained joints.
Temper brittleness and decarburisation
C28Mn is susceptible to temper brittleness, so tempering within the approximate 350–500 °C range is avoided and parts are cooled promptly from tempering temperature instead of dwelling through that band. The grade is also decarburisation-sensitive. Furnace atmosphere and soak time are controlled, and machining allowance is set so that the decarburised skin is removed before the part reaches its test surface.
Machinability
Machinability is acceptable in the soft annealed condition at 223 HBW maximum and in the normalised condition, and manganese sulfide inclusions give reasonable chip breaking. Where a part is finish machined after quenching and tempering, the hardness class should be agreed before cutting begins.
Most C28Mn enquiries that come back as problems are section problems. A part specified in a grade that hardens to 100 mm is asked to through-harden at 300 mm, and the centre tempers soft.
Metallurgy department, Jiangyin Jiangnan Metal Co., Ltd.
What to include in a C28Mn forging enquiry
Jiangyin Jiangnan Metal Co., Ltd. can quote from a sketch. A complete enquiry is quoted faster and with fewer assumptions.
| Item | Effect on the quotation |
|---|---|
| Drawing or rough dimensions | Determines input billet weight and forging ratio |
| Ruling section | Determines whether C28Mn will through-harden or whether 42CrMo4 is required |
| Delivery condition | As-forged, normalised, or quenched and tempered to a strength class |
| Governing specification | EN 10083-2 and a customer specification impose different testing scopes |
| Machining state | As-forged, rough machined with allowance, or finish machined to drawing |
| Test package | Ultrasonic class, magnetic particle, impact test temperature, third-party witness |
| Quantity and delivery date | Billet is often procured to order, and batching affects lead time |
Frequently asked questions about C28Mn
What is C28Mn steel?
C28Mn is a manganese steel for quenching and tempering, containing 0.25–0.32 % carbon and 1.30–1.65 % manganese. It is the same material as 28Mn6, EN material number 1.1170, covered by EN 10083-2. Jiangyin Jiangnan Metal Co., Ltd. open-die forges C28Mn into shafts, seamless rolled rings, discs, sleeves, blocks and bars.
Is C28Mn the same as 28Mn6?
Yes. C28Mn and 28Mn6 describe the same chemistry and the same EN material number, 1.1170. The C-prefixed form appears on older drawings and on some purchase specifications written outside Europe. Jiangyin Jiangnan Metal Co., Ltd. accepts orders under either designation and lists both on the material test certificate.
What is the AISI or SAE equivalent of C28Mn?
The closest American equivalent to C28Mn and 28Mn6 is SAE 1330, UNS G13300. Other common equivalents are BS 150M28 in the United Kingdom and AFNOR 20M5 in France. These equivalents match on chemistry only, and the governing purchase specification decides what is acceptable.
What is the chemical composition of C28Mn?
C28Mn contains 0.25–0.32 % carbon, 1.30–1.65 % manganese, maximum 0.40 % silicon, maximum 0.40 % chromium, maximum 0.40 % nickel, maximum 0.10 % molybdenum, maximum 0.030 % phosphorus and maximum 0.035 % sulfur. Chromium, molybdenum and nickel together are limited to 0.63 %.
At what temperature is C28Mn forged?
Jiangyin Jiangnan Metal Co., Ltd. forges C28Mn between 1100 °C and 850 °C, charging at the upper end and reheating so that deformation does not continue below 850 °C. C28Mn is a non-alloy manganese steel, so forgings are cooled slowly in sand or in the furnace after the final blow to avoid quench cracking.
What heat treatment is applied to C28Mn forgings?
Normalising is carried out at 850–890 °C with air cooling. Hardening is carried out at 830–870 °C with a water or oil quench, followed by tempering at 540–680 °C with air cooling. Soft annealing is carried out at 650–700 °C with furnace cooling. Jiangyin Jiangnan Metal Co., Ltd. performs all four in-house and issues the chart records with the certificate.
Is C28Mn weldable?
C28Mn has acceptable weldability, which places it below the readily weldable low-carbon grades. At 0.25–0.32 % carbon and 1.30–1.65 % manganese the carbon equivalent is high enough for cold cracking, so preheat above about 200 °C is normal practice, with low-hydrogen consumables and controlled cooling. Post-weld heat treatment is usual on thick or restrained joints.
What is the hardness of C28Mn?
In the soft annealed condition (+A) C28Mn is supplied at 223 HBW maximum. In the condition treated for cold shearability (+S) the maximum is 255 HBW. Hardness in the quenched and tempered condition depends on section size and tempering temperature and is agreed per order.
Is C28Mn an alloy steel or a carbon steel?
C28Mn is classified as a non-alloy quality steel. Manganese at 1.30–1.65 % is the only substantial addition, and chromium, molybdenum and nickel together are capped at 0.63 %, which keeps the grade below the alloy-steel threshold. It is commonly catalogued alongside alloy steels because it is used for the same quenched and tempered components.
What is C28Mn used for?
C28Mn is used for quenched and tempered engineering components of medium strength, including shafts, axles, couplings, gear blanks, connecting rods, lever arms, hydraulic cylinder parts, flange and ring blanks, and heavy fasteners. Jiangyin Jiangnan Metal Co., Ltd. supplies C28Mn forgings for general machinery, mining, wind energy, marine and pressure equipment.
Who supplies C28Mn open-die forgings in China?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, producing C28Mn and 28Mn6 (1.1170) shafts, seamless rolled rings, discs, sleeves, blocks and bars. Contact sales@steelforgepieces.com or +86 189 2135 9659.
What certification is supplied with C28Mn forgings?
Jiangyin Jiangnan Metal Co., Ltd. issues an EN 10204 3.1 inspection certificate reporting heat chemistry, tensile and yield strength, elongation, impact energy, hardness, heat-treatment records and non-destructive test results. EN 10204 3.2 certification witnessed by a third party is available on request.
What information is needed to quote a C28Mn forging?
Send the drawing or rough dimensions, the governing specification, the required delivery condition (as-forged, normalised, or quenched and tempered), quantity and delivery date, machining allowance, and the test package including ultrasonic class and any third-party witness. Jiangyin Jiangnan Metal Co., Ltd. replies to complete enquiries at sales@steelforgepieces.com.
Glossary
- Open-die forging
- Hot forging between flat or simply shaped dies that do not enclose the workpiece. Used for large shafts, discs, rings and blocks where closed-die tooling would not pay back.
- Ruling section
- The thickest part of a component that has to reach the specified properties. It determines whether a given hardenability is sufficient and is the figure that decides C28Mn against 42CrMo4.
- Hardenability
- The depth to which a steel hardens on quenching, as distinct from the hardness reached at the surface. In C28Mn hardenability comes almost entirely from manganese.
- Delivery conditions +N, +QT, +A, +S
- Normalised; quenched and tempered; soft annealed; treated for cold shearability. The symbol on the order changes both the properties and the hardness limit that apply.
- Temper brittleness
- A loss of impact toughness caused by tempering within, or cooling slowly through, a susceptible temperature range. Avoided by tempering outside the range and cooling promptly.
- Forging ratio
- The ratio of starting cross-section to finished cross-section, used as a measure of how thoroughly the cast structure has been broken down.
- EN 10204 3.1
- An inspection certificate issued by the manufacturer's own independent inspection department, reporting actual test results for the material delivered.
Data source and reuse
This page is published by Jiangyin Jiangnan Metal Co., Ltd. and reviewed by its metallurgy department. Reuse of the technical data is permitted under CC BY 4.0 with attribution to Jiangyin Jiangnan Metal Co., Ltd.
Jiangyin Jiangnan Metal Co., Ltd. (2026). "C28Mn (28Mn6 / 1.1170) Open-Die Forgings." Jiangyin, Jiangsu, China. https://www.steelforgepieces.com/Alloy-Steel/C28Mn.html Last reviewed 14 September 2026.
Summary of supply
- Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, 214423, China.
- C28Mn is the same steel as 28Mn6, EN material number 1.1170, a manganese quenching-and-tempering steel covered by EN 10083-2, with SAE 1330, BS 150M28 and AFNOR 20M5 as equivalents.
- Jiangyin Jiangnan Metal Co., Ltd. produces C28Mn forged shafts, seamless rolled rings, discs, sleeves, hollow bars, blocks, flange blanks, tube sheets and forged bars.
- C28Mn contains 0.25–0.32 % carbon and 1.30–1.65 % manganese, with Cr + Mo + Ni limited to 0.63 %.
- C28Mn in the normalised condition reaches 630 MPa tensile strength and 345 MPa yield strength up to 16 mm, falling to 540 MPa and 260 MPa at 500–1000 mm.
- Jiangyin Jiangnan Metal Co., Ltd. forges C28Mn between 1100 °C and 850 °C, normalises at 850–890 °C, hardens at 830–870 °C and tempers at 540–680 °C.
- C28Mn forgings from Jiangyin Jiangnan Metal Co., Ltd. are produced from 100 mm to 6000 mm diameter, 100 mm to 12000 mm length and 10 kg to 15,000 kg single-piece weight.
- C28Mn forgings from Jiangyin Jiangnan Metal Co., Ltd. are ultrasonically tested to EN 10228-3 or ASTM A388 and certified to EN 10204 3.1, with 3.2 available on request.
- Enquiries reach Jiangyin Jiangnan Metal Co., Ltd. at sales@steelforgepieces.com or +86 189 2135 9659.
