Forged bars
Round bars and rods, square bars, rectangular and flat bars, hexagon bars. Rough turned, peeled, black or proof machined.
UNS S44004 (AISI 440C) Forgings: Bars, Rings, Discs and Sleeves
SAE 51440C / EN 1.4125 X105CrMo17 / JIS SUS440C / AFNOR Z100CD17. Open-die forged to your drawing by Jiangyin Jiangnan Metal Co., Ltd., Jiangsu, China.
UNS S44004 is the UNS designation for AISI/SAE 440C, a high-carbon, high-chromium martensitic stainless steel with 0.95 to 1.20 % carbon and 16.00 to 18.00 % chromium, plus up to 0.75 % molybdenum. It reaches the highest hardness of any stainless steel, around 58 to 60 HRC, after hardening and low-temperature tempering, with high wear resistance and moderate corrosion resistance close to grade 410.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu, China. We forge UNS S44004 into round bars, seamless rolled rings, discs, blocks, hollow bars and sleeves to customer drawings, supplied annealed at 269 HBW max hot finished or 285 HBW max cold finished, or hardened and tempered. Enquiries: sales@steelforgepieces.com, +86-189-2135-9659.
- UNS number
- S44004
- AISI / SAE
- 440C / SAE 51440C
- EN / Werkstoff
- 1.4125 (X105CrMo17)
- JIS
- SUS440C
- Structure
- Martensitic stainless
- Carbon
- 0.95 to 1.20 %
- Chromium
- 16.00 to 18.00 %
- Hardness capability
- 58 to 60 HRC
- Annealed hardness
- 269 HBW max, hot finished
- Density
- 7 650 kg/m³
- Forging range
- 1 050 to 1 150 °C
- Forms supplied
- Bars, rings, discs, sleeves
What UNS S44004 / 440C is
UNS S44004 carries the most carbon of any grade in the AISI 400 series. The 0.95 to 1.20 % carbon level is what separates it from 440A and 440B. That carbon forms chromium carbides, which is where the abrasive wear resistance comes from and why the steel can be through hardened to roughly 60 HRC, a figure no other stainless grade reaches. The cost is corrosion performance. Carbon locked into carbides is chromium no longer available to protect the matrix, so 440C sits close to grade 410 and below grade 431, the ferritic 400-series grades and every austenitic 300-series grade.
Annealed, the grade machines acceptably. It behaves a little like a high-speed steel and throws tough stringy chips, so chip breakers earn their keep. Hardened, it is hard to machine, which is why nearly every 440C part is rough machined soft, hardened, then finish ground. Thin sections can be air cooled. Heavier sections need an oil quench to harden through.
Why forge 440C instead of cutting it from solid bar. Open-die forging and ring rolling break up the as-cast carbide network and line the grain flow up with the shape of the part. On bearing races, valve seats and sleeves that continuous grain flow gives better fatigue and wear behaviour than a part machined out of oversize stock, and on large or hollow shapes it saves a lot of material.
Equivalent grades and applicable specifications
| Region or body | Standard | Designation |
|---|---|---|
| USA (UNS) | UNS | S44004 |
| USA (AISI / SAE) | ASTM A276 / A276M | Type 440C, SAE 51440C |
| Europe | EN 10088 | 1.4125, X105CrMo17 |
| Japan | JIS G4303 | SUS440C |
| France | AFNOR | Z100CD17 |
| Aerospace | SAE AMS | AMS 5630 (bar, wire, forgings), AMS 5618 (vacuum melted), AMS 5880 (bearing quality) |
440C material also falls under ASTM A276/SA276 for bars and shapes, A314 for billets and bars for forging, A473 for stainless forgings, A484 for general requirements, A493 for cold-heading wire, A580 for wire and A756, as well as QQ-S-763. Name the specification on your enquiry and we certify to it.
Chemical composition of UNS S44004
| Element | Min % | Max % |
|---|---|---|
| Carbon (C) | 0.95 | 1.20 |
| Silicon (Si) | – | 1.00 |
| Manganese (Mn) | – | 1.00 |
| Chromium (Cr) | 16.00 | 18.00 |
| Molybdenum (Mo) | – | 0.75 |
| Phosphorus (P) | – | 0.040 |
| Sulphur (S) | – | 0.030 |
| Nickel (Ni) | – | optional addition |
| Iron (Fe) | Balance | |
A nickel addition is optional and is not required by ASTM A276. Watch the differences between specifications: EN 10088 grade 1.4125 narrows molybdenum to 0.40 to 0.80 %, while AMS 5630 calls for Mo 0.40 to 0.65 %, Ni 0.75 % max and Cu 0.50 % max. Tell us the governing specification before we buy the heat.
Mechanical properties
Annealed condition, specification requirements
| Specification | Finish | Brinell hardness | Hardening capability |
|---|---|---|---|
| ASTM A276 440C | Hot finished | 269 HBW max | 58 HRC min on a 9.50 mm test bar, air cooled from 1 020 °C |
| ASTM A276 440C | Cold finished | 285 HBW max | |
| AS 2837 440C | – | 269 HBW max | 59 HRC min on a 10 mm test bar, oil quenched from 1 010 to 1 070 °C |
Annealed condition, typical as-supplied values
| Property | Typical value |
|---|---|
| Tensile strength | 785 MPa |
| Yield strength, 0.2 % proof | 420 MPa |
| Elongation in 50 mm | 15 % |
| Impact, Charpy | 6 J |
| Hardness | 240 HB, about 24 HRC |
Other published datasheets give similar annealed figures, around 758 MPa tensile, 448 MPa yield and 14 % elongation at 269 HB max. These are typical values, not guaranteed minima. Results depend on section size and anneal cycle.
Hardened and tempered, effect of tempering temperature
| Temper °C | Tensile MPa | 0.2 % yield MPa | Elong. % in 50 mm | Hardness HRC | Charpy V, J |
|---|---|---|---|---|---|
| 204 | 2 030 | 1 900 | 4 | 59 | 9 |
| 260 | 1 960 | 1 830 | 4 | 57 | 9 |
| 316 | 1 860 | 1 740 | 4 | 56 | 9 |
| 371 | 1 790 | 1 660 | 4 | 56 | 9 |
A typical hardened bar, austenitised at 1 038 °C, oil quenched and tempered at 316 °C, reports around 1 965 MPa tensile, 1 896 MPa yield, 2 % elongation, 10 % reduction of area and about 580 HB. Ductility and impact energy are low in this grade by nature. 440C is chosen for hardness and wear, not for toughness.
Physical properties
| Property | Value |
|---|---|
| Density | 7 650 kg/m³ |
| Modulus of elasticity | 200 GPa |
| Mean thermal expansion, 0 to 100 °C | 10.1 µm/m·°C |
| Mean thermal expansion, 0 to 200 °C | 10.3 µm/m·°C |
| Mean thermal expansion, 0 to 600 °C | 11.7 µm/m·°C |
| Thermal conductivity at 100 °C | 24.2 W/m·K |
| Specific heat, 0 to 100 °C | 460 J/kg·K |
| Electrical resistivity | 600 nΩ·m |
| Magnetic response | Ferromagnetic in all conditions |
Forging and heat treatment of UNS S44004
440C is unforgiving in the forge shop. The carbon content makes it crack if it is heated too fast, finished too cold, or cooled too quickly after forging. This is the route we follow in Jiangyin.
Forging
- Preheat 760 to 820 °C, slowly and evenly, to keep thermal shock out of the billet.
- Heat to 1 050 to 1 150 °C and soak until the temperature is uniform through the section, then forge at once. Overheating costs toughness and ductility for good.
- Do not forge below 900 °C. Reheat rather than keep hammering a cooling workpiece.
- Cool slowly in a furnace, warm dry lime or ashes to room temperature. Air cooling straight from the forge can crack the part.
- Anneal straight away after forging. Do not leave forgings sitting in the as-forged martensitic state.
Annealing
For maximum softness and the best machinability, anneal at 843 to 871 °C and cool slowly in the furnace. This is the condition we normally ship bars, rings and discs in, so your machine shop can rough out the shape.
Hardening and tempering
Preheat around 760 °C, austenitise near 1 010 °C (1 850 °F), with published practice running up to about 1 063 °C, then quench in warm oil or air cool depending on section thickness. Temper without delay. At least one hour at 149 to 177 °C (300 to 350 °F) takes the peak stress out while holding around 60 HRC. Tempering higher trades hardness for a modest further stress reduction, as Table 5 shows. Avoid overheating during austenitising, since retained austenite and coarse grain will stop the part reaching full hardness.
Welding
440C is seldom welded. Where it cannot be avoided, preheat to about 260 °C (500 °F) and follow with a post-weld anneal at 732 to 760 °C (1 350 to 1 400 °F) for roughly 6 hours, cooling slowly in the furnace to prevent cracking. Matching composition consumables give weld metal closest to the base metal. Otherwise AWS E/ER309 may be considered.
UNS S44004 forged product range
Everything below is open-die forged or ring rolled to the customer drawing. There is no fixed catalogue. Send a drawing or a dimensioned sketch and we will advise the forging route, machining allowance and weight.
Seamless rolled rings
Ring rolled and open-die forged rings for bearing races, valve seat rings, spacers and retaining rings. Rectangular and contoured profiles.
Hollow bars and sleeves
Bushes, bushings, sleeves, cylinders, barrels, casings, shells, hubs and housings, trepanned or mandrel forged.
Discs, blocks and plates
Upset forged discs and disks, rectangular blocks and forged plate for die blocks, gauge blocks and mould bases.
Shafts and stepped forgings
Valve stems, pivot pins, nozzles, spindles and stepped shafts forged close to contour to cut machining time.
Near-net custom shapes
Valve bodies, bonnets, flanged and contoured components forged to drawing for valve, pump and bearing makers.
Where UNS S44004 is used
440C goes into parts that have to resist abrasive wear and hold a hard, accurate surface while still seeing moisture, mild acids or petroleum products. Common uses are ball bearings and bearing races, cutlery and knife blades, moulds and dies, gauge blocks and measuring instruments, surgical and dental instruments, valve components including seats, seat rings, stems, bodies and bonnets, needle valves and ball check valves, pump parts, nozzles, pivot pins, and wear parts in textile machinery.
We supply this grade mainly into oil and gas valve manufacture, petrochemical processing, bearing production, food and pharmaceutical processing equipment, precision instrumentation and general wear-part engineering.
Testing, condition and documentation
Forgings can be supplied as forged, annealed, or hardened and tempered to an agreed hardness band, and machined to a finished or semi-finished drawing. State the delivery condition on the enquiry, because it changes both the forging allowance and the lead time.
- Chemical analysis. Spectrographic heat analysis against ASTM A276, EN 10088 or AMS 5630 limits, whichever governs.
- Mechanical testing. Tensile, hardness in HBW or HRC and impact testing on a representative test piece or prolongation.
- Hardenability check. Response test confirming the specified minimum HRC after the agreed hardening cycle.
- Non-destructive examination. Ultrasonic, magnetic particle, dye penetrant and dimensional inspection on request.
- Certification. EN 10204 3.1 mill test certificate as standard. Third-party 3.2 inspection by agreement.
Confirm with our sales team which certifications, approvals and test scopes apply to your project and destination market before placing an order.
Frequently asked questions about UNS S44004
What is UNS S44004?
UNS S44004 is the Unified Numbering System designation for AISI/SAE 440C, a high-carbon martensitic stainless steel with 0.95 to 1.20 % carbon and 16.00 to 18.00 % chromium. It reaches the highest hardness of any stainless steel, roughly 58 to 60 HRC after hardening and low tempering, and is used for bearings, cutlery, valve seats, moulds and wear parts.
What is the equivalent of UNS S44004 in Europe and Japan?
EN 1.4125 / X105CrMo17 under EN 10088 in Europe, SUS440C under JIS G4303 in Japan, and Z100CD17 under AFNOR in France. Aerospace equivalents are AMS 5630, AMS 5618 for vacuum melted material and AMS 5880 for bearing quality. Note that EN 1.4125 specifies Mo 0.40 to 0.80 % and AMS 5630 specifies Mo 0.40 to 0.65 %, while ASTM A276 only caps Mo at 0.75 %.
How hard can 440C be heat treated?
Roughly 58 to 60 HRC. ASTM A276 requires 440C to be capable of 58 HRC minimum on a 9.50 mm test bar air cooled from 1 020 °C. AS 2837 requires 59 HRC minimum on a 10 mm bar oil quenched from 1 010 to 1 070 °C. In the annealed delivery condition it is far softer, 269 HBW maximum hot finished or 285 HBW maximum cold finished.
Is 440C corrosion resistant?
Moderately. It handles fresh water, organic materials, mild acids and petroleum products in mild domestic and industrial environments, and performs best fully hardened with a smooth finish. Corrosion resistance is close to grade 410 and below grade 431, the ferritic 400-series and all austenitic 300-series grades, because much of the chromium is tied up in carbides. It is not a replacement for duplex or 316 in chloride service.
What is the forging temperature for 440C?
Preheat 760 to 820 °C, heat to 1 050 to 1 150 °C and forge at once. Never finish below 900 °C. Cool slowly in a furnace, warm lime or ash, then anneal immediately at 843 to 871 °C. Air cooling straight after forging risks cracking.
Does 440C machine well?
Annealed, it machines acceptably for all normal operations and behaves a little like a high-speed steel because of the carbon. The chips come off tough and stringy, so chip curlers and breakers matter. Hardened, it is difficult to machine and is normally finished by grinding. Where heavy machining is unavoidable, the free-machining variants 440F and 440F Se exist.
What sizes and shapes can you forge in UNS S44004?
Jiangyin Jiangnan Metal Co., Ltd. makes this grade as forged round, square, flat and hex bars, seamless rolled rings, hollow bars and sleeves, discs, blocks and stepped shafts, all to drawing rather than from a stock list. Send your drawing, required specification, delivery condition and quantity to sales@steelforgepieces.com or call +86-189-2135-9659 and we will confirm size capability, weight and lead time.
Can you supply 440C forgings heat treated and machined?
Yes. Forgings go out as forged, annealed for your own machining, or hardened and tempered to an agreed hardness band. We can rough machine, proof machine or finish machine to drawing. Mill test certificates to EN 10204 3.1 are issued as standard.
Request a quotation for UNS S44004 forgings
Jiangyin Jiangnan Metal Co., Ltd., open-die forging factory, Jiangyin, Jiangsu, China. Send your drawing, grade and quantity and you get a technical reply and a price from the factory, not from a trading desk.
No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Tel: +86-189-2135-9659
Email: sales@steelforgepieces.com
Related grades we forge
If 440C is not the right balance of hardness and corrosion resistance for your part, these are the grades customers usually ask us to quote alongside it.