1.4125 at a glance
- EN name
- X105CrMo17Material number 1.4125
- Type
- Martensitic stainlessHigh-carbon, Cr–Mo alloyed
- Standard
- EN 10088-3:2023Martensitic special grades
- US equivalent
- AISI 440C · UNS S44004ASTM A276 / A473 / F899
- Carbon
- 0.95–1.20 %Highest C of the 400 series
- Chromium
- 16.0–18.0 %Molybdenum 0.40–0.80 %
- Annealed hardness
- ≤ 285 HBWCondition +A, thickness ≤ 100 mm
- Hardened
- 58–60 HRCQuenched and tempered below 400 °C
- Density
- 7.7 g/cm³Magnetic in all conditions
- Forged forms
- Rings · bars · discsSleeves, blocks, valve components
- Supplied by
- Jiangyin Jiangnan MetalJiangyin, Jiangsu, China · since 1997
- Minimum order
- 10 kgLead time 20–60 days
What is 1.4125 stainless steel?
1.4125 is a high-carbon martensitic stainless steel standardised in EN 10088-3 under the name X105CrMo17. Its high carbon content lets it be hardened to 58–60 HRC, giving it the best wear resistance of any stainless steel, at the cost of reduced toughness and only moderate corrosion resistance.
The alloy sits at the top of the 17 % chromium martensitic family. Carbon at 0.95–1.20 % forms a dense dispersion of chromium carbides that carries the hardness and the wear resistance; the 0.40–0.80 % molybdenum addition improves hardenability, tempering resistance and pitting behaviour compared with the molybdenum-free grades. Enough chromium stays in solution after hardening for the steel to remain stainless in mild environments, though the carbide-forming chromium is no longer available for corrosion protection. This is why 1.4125 is less corrosion resistant than 1.4021 or 1.4057 despite containing more chromium.
The steel is delivered soft annealed at a maximum of 285 HBW so it can be machined, then hardened and tempered by the part maker to the required working hardness. Electro-slag remelted (ESR) material is specified where carbide size and distribution matter, as they do for bearing races and precision measuring tools, because 1.4125 solidifies with coarse chromium-rich primary carbides and is prone to carbide banding and segregation in heavy sections.
Where 1.4125 sits against neighbouring grades
| Grade | EN name | C % | Cr % | Mo % | Character |
|---|---|---|---|---|---|
| 1.4125 | X105CrMo17 | 0.95–1.20 | 16.0–18.0 | 0.40–0.80 | Maximum hardness and wear resistance |
| 1.4112 | X90CrMoV18 | 0.85–0.95 | 17.0–19.0 | 0.90–1.30 | Vanadium-alloyed, better edge retention |
| 1.4116 | X50CrMoV15 | 0.45–0.55 | 14.0–15.0 | 0.50–0.80 | Tougher cutlery grade, lower hardness |
| 1.4122 | X39CrMo17-1 | 0.33–0.45 | 15.5–17.5 | 0.80–1.30 | Quench-and-tempered engineering grade |
| 1.4057 | X17CrNi16-2 | 0.12–0.22 | 15.0–17.0 | — | Nickel-bearing, tough, better corrosion |
Composition limits from EN 10088-3. Move up this table for hardness and wear, down it for toughness and corrosion resistance. Jiangyin Jiangnan Metal forges 1.4057, 440A and 431 alongside 1.4125.
1.4125 chemical composition
EN 10088-3:2023 specifies 1.4125 as 0.95–1.20 % C, ≤ 1.00 % Si, ≤ 1.00 % Mn, ≤ 0.040 % P, ≤ 0.030 % S, 16.0–18.0 % Cr and 0.40–0.80 % Mo, with iron as the balance.
| Element | Minimum | Maximum | Role in the alloy |
|---|---|---|---|
| Carbon (C) | 0.95 | 1.20 | Forms chromium carbides; sets attainable hardness |
| Silicon (Si) | — | 1.00 | Deoxidiser, residual from melting |
| Manganese (Mn) | — | 1.00 | Deoxidiser, sulphur control |
| Phosphorus (P) | — | 0.040 | Impurity, embrittles grain boundaries |
| Sulphur (S) | — | 0.030 | Impurity; see note on polishability below |
| Chromium (Cr) | 16.0 | 18.0 | Corrosion resistance and carbide formation |
| Molybdenum (Mo) | 0.40 | 0.80 | Hardenability, tempering and pitting resistance |
| Iron (Fe) | Balance | Matrix | |
1.4125 is listed among the martensitic special grades in EN 10088-3. The 2023 edition superseded EN 10088-3:2014; 1.4125 is carried forward with its composition limits unchanged.
EN and ASTM are not interchangeable on molybdenum. EN 10088-3 requires 0.40–0.80 % Mo for 1.4125. ASTM A276 and the AMS specifications for 440C set molybdenum at 0.75 % maximum with no minimum, so material certified to 440C can legitimately contain almost no molybdenum and still fail an EN 1.4125 check. Where a drawing calls for 1.4125 specifically, say so on the order and do not write "440C or equivalent".
Sulphur and polishability. EN 10088-3 sets sulphur at 0.030 % maximum with no minimum: 1.4125 is not a free-machining grade and sulphur is not added to it deliberately. Sulphur forms manganese sulphide inclusions, which ease machining but reduce pitting resistance and show as defects on a polished face. Where a mirror finish or the best corrosion resistance is needed, some mills restrict their own 1.4125 to 0.015 % sulphur maximum. It is decided at the melt, so put it on the enquiry and not on a later revision.
Check the edition on the certificate. Many datasheets for this grade still cite EN 10088-3:2005. That edition was superseded by EN 10088-3:2014 and then by EN 10088-3:2023. The composition limits are unchanged, but the standard reference on a mill certificate should be the current edition.
1.4125 equivalent grades and specifications
1.4125 is equivalent to AISI 440C and UNS S44004 in the United States, SUS440C in Japan, 102Cr17Mo (formerly 9Cr18Mo) in China, Z100CD17 in France and 95Kh18 / 110Kh18M in the GOST system.
| Region / system | Designation | Governing standard |
|---|---|---|
| Europe (EN) | X105CrMo17 · 1.4125 | EN 10088-3 (long products), EN 10088-2 (flat) |
| Germany (DIN) | X105CrMo17 · Werkstoff 1.4125 | DIN EN 10088-3 |
| USA (AISI / UNS) | 440C · S44004 | ASTM A276/A276M, ASTM A473, ASTM F899 |
| USA (aerospace) | AMS 5630 (general purpose), AMS 5880 (bearing quality) | SAE AMS |
| Japan (JIS) | SUS440C | JIS G 4303 |
| China (GB) | 102Cr17Mo (old designation 9Cr18Mo) | GB/T 1220, GB/T 20878 |
| France (AFNOR) | Z100CD17 | NF A35-572 / NF S94-090 |
| Russia (GOST) | 95Kh18 · 110Kh18M | GOST 5632 |
| Italy (UNI) | X102CrMo17KU | UNI |
| India (IS) | X108Cr17Mo | IS 6603 |
Equivalents are close but not always identical. Chinese 102Cr17Mo is the current GB designation adopted in GB/T 1220-2007 and GB/T 20878-2007 for the grade previously called 9Cr18Mo. Where a contract names one standard, order to that standard: Jiangyin Jiangnan Metal melts to the customer's chemistry and certifies against the specification stated on the order.
Which specification should appear on the order?
- Bar and rod, general engineering: EN 10088-3 or ASTM A276/A276M.
- Forgings: ASTM A473 for stainless steel forgings, or EN 10088-3 with the forged condition stated. A473 lists the 440 series with a maximum annealed hardness of 269 HB.
- Surgical and medical instruments: ASTM F899.
- Aerospace: AMS 5630 for general-purpose bars, wire and forgings, or AMS 5880 for bearing-quality bars, wire, forgings and forging stock, usually with a melt-route requirement such as ESR or VAR.
Physical properties of 1.4125
1.4125 has a density of 7.7 g/cm³, a modulus of elasticity of about 200 GPa at 20 °C, a thermal conductivity near 24 W/m·K and an electrical resistivity of roughly 0.60 µΩ·m. It is ferromagnetic in every delivery condition.
| Property | Metric value | Imperial value |
|---|---|---|
| Density | 7.7 g/cm³ | 0.278 lb/in³ |
| Modulus of elasticity | 200 GPa | 29.0 × 10³ ksi |
| Poisson's ratio | 0.28 | 0.28 |
| Thermal conductivity (at 100 °C) | 24 W/m·K | 167 BTU·in/h·ft²·°F |
| Specific heat capacity | 460 J/kg·K | 0.11 BTU/lb·°F |
| Coefficient of thermal expansion (20–100 °C) | 10.4 × 10⁻⁶ /K | 5.8 × 10⁻⁶ /°F |
| Electrical resistivity | 0.60 µΩ·m (0.60 Ω·mm²/m) | 23.6 µΩ·in |
| Melting range | approx. 1,370–1,480 °C | approx. 2,500–2,700 °F |
| Magnetic response | Ferromagnetic, annealed and hardened | |
Values are typical supplier data, not guaranteed minima; EN 10088-3 does not specify physical properties. Thermal expansion rises with temperature, reaching roughly 12.0 × 10⁻⁶ /K over the 20–500 °C range. Thermal conductivity is quoted differently on either side of the Atlantic: 24 W/m·K is the value at 100 °C used on US datasheets, while several European mills publish about 15 W/m·K at 20 °C. Modulus is likewise given as 200 GPa by most sources and 215 GPa by others, so check which figure a calculation depends on.
Two figures worth checking on any 440C datasheet. Electrical resistivity for this grade is about 0.60 µΩ·m; values around 0.06 µΩ·m appear on a number of web datasheets and are a decimal-point error of a factor of ten. Density is 7.7 g/cm³, not 7.65 or 7.8. The differences are small, but they show up when weight is estimated from a drawing for a 30-tonne forging.
Mechanical properties and hardness
EN 10088-3 places a single mechanical requirement on 1.4125: in the annealed condition (+A), at thicknesses up to 100 mm, hardness must not exceed 285 HBW. No proof strength, tensile strength or elongation values are specified, because the grade is supplied soft for machining and hardened afterwards.
| Thickness d | Heat-treatment condition | Rp0.2 | Rm | Elongation A | Max hardness |
|---|---|---|---|---|---|
| d ≤ 100 mm | +A (annealed) | not specified | not specified | not specified | 285 HBW |
Correction to a widely copied table. Many 1.4125 datasheets publish "proof stress 448–1900 MPa, tensile strength 758–2030 MPa, elongation 4–14 %" and attribute it to EN 10088-3. Those figures are aggregated values covering 440C across every heat-treatment condition; they are not requirements of EN 10088-3, which specifies only the maximum annealed hardness shown above. Quoting them on an order or a certificate is a specification error.
Typical properties after hardening and tempering
The properties that matter in service come from the customer's own heat treatment. Typical values after austenitising at 1,010–1,070 °C, quenching, and tempering at the temperature shown:
| Tempering temperature | Resulting hardness | Typical use |
|---|---|---|
| As-quenched | ≥ 58 HRC | Before tempering; temper immediately |
| 150–200 °C | 58–60 HRC | Bearings, knives, wear parts |
| 200–300 °C | 56–58 HRC | Valve seats, gauges, pump parts |
| 300–400 °C | 52–56 HRC | Where some toughness is traded for hardness |
| 425–565 °C | Avoid. Impact toughness and corrosion resistance both fall in this range | |
| Annealed (+A) | ≤ 285 HBW | Delivery condition for machining |
Deep-freezing before tempering raises attainable hardness by a point or two, and double tempering is normally specified when it is used. 1.4125 has low impact toughness at full hardness and Charpy values are not normally specified for it; where impact energy is a contract requirement, a lower-carbon martensitic grade such as 1.4057 or 1.4122 is usually the better choice.
On tensile strength. The tensile figure published for this grade is approximately 1,965 MPa (285 ksi), and it is measured at 56–57 HRC, after hardening from about 1,040 °C and tempering near 250 °C, not at full 60 HRC hardness. In the annealed condition EN 10088-3 caps tensile strength at 900 MPa, with a typical value near 760 MPa.
Hardness, not tensile strength, is the property specified and measured for 1.4125. ASTM A370 and E140 tabulate approximate tensile strength only to about 500 HBW (roughly 52 HRC); above that there is no standardised hardness-to-tensile conversion, and hard martensitic steels often fracture below the converted figure. Converted strength values for fully hardened 1.4125 should not be used for design.
Heat treatment and forging of 1.4125
1.4125 is forged between 1,050 °C and 1,150 °C, annealed at 780–840 °C to a maximum of 285 HBW, hardened from 1,010–1,070 °C in oil or air, and tempered below 400 °C to reach 58–60 HRC. Tempering between 425 °C and 565 °C must be avoided.
| Operation | Temperature | Cooling | Result / remarks |
|---|---|---|---|
| Preheat for forging | 750–850 °C, soak through | — | Slow heating below 700 °C; this steel cracks if rushed |
| Hot forging | 1,050–1,150 °C | Slow furnace or insulated cool | Do not finish below 900 °C; anneal immediately after forging |
| Soft annealing (+A) | 780–840 °C | Furnace or still air | ≤ 285 HBW per EN 10088-3; delivery condition |
| Full anneal for maximum softness | 840–875 °C, long soak | Furnace cool below 600 °C, then air | Approx. 223–255 HBW; best machinability |
| Process (sub-critical) anneal | 730–760 °C | Air | Stress relief between machining operations |
| Hardening (austenitising) | 1,010–1,070 °C | Warm oil, air or gas | ≥ 58 HRC as-quenched; do not overheat, as grain coarsens |
| Sub-zero treatment | −73 °C or lower | Return to room temperature | Reduces retained austenite, stabilises dimensions; do it before tempering |
| Tempering | 150–370 °C, minimum 1 h | Air | 58–60 HRC; temper immediately after quenching |
| Stress relief (hardened parts) | 150–200 °C | Air | After grinding or EDM |
Do not temper 1.4125 between 425 °C and 565 °C. Chromium carbides precipitate at the grain boundaries in this range, and both impact toughness and corrosion resistance drop sharply. For the best corrosion resistance keep the tempering temperature below about 427 °C; some mills quote the band to avoid slightly wider, at 427–593 °C.
Machining, grinding and welding
Machine 1.4125 in the annealed condition only. Even annealed it is a difficult steel: the carbide content abrades tooling, and the chip is tough and stringy. Use rigid set-ups, positive rake, generous coolant and reduced speeds against an austenitic grade. Once hardened, the practical routes are grinding, EDM and hard turning with CBN.
Welding is not recommended. The carbon content makes the heat-affected zone brittle and crack-prone. Where a joint is unavoidable, preheat to about 260 °C, hold that temperature through welding, and anneal at 730–760 °C for six to eight hours with a slow furnace cool immediately afterwards, never letting the part fall below 260 °C in between. Jiangyin Jiangnan Metal supplies 1.4125 as single-piece forgings so that welded joints are not needed.
Passivate after machining. Corrosion resistance depends on a clean, scale-free, passivated surface. A polished 1.4125 surface performs markedly better than an as-ground one, and free iron from tooling will rust and start pitting if it is not removed.
Corrosion resistance and service limits
1.4125 offers moderate corrosion resistance. It holds up in fresh water, steam, atmospheric exposure, petroleum, alcohol, ammonia and foodstuffs, but is not adequate for seawater, chlorides at elevated temperature, or reducing acids. It is chosen for wear resistance in mildly corrosive service, not for corrosion resistance on its own.
Suitable service
- Atmospheric and industrial atmospheres
- Fresh water, steam
- Petroleum products, alcohols, ammonia
- Foodstuffs and food-processing equipment
- Mild oxidising conditions
Unsuitable service
- Seawater and marine splash zones
- High chloride concentrations, especially hot
- Reducing acids
- Sour service to NACE MR0175 / ISO 15156
- Anywhere Charpy impact energy is specified
What improves performance
- Hardened and tempered below 427 °C
- Fine polished rather than ground surface
- Passivation after machining
- ESR material for cleaner carbide structure
- Avoiding the 425–565 °C tempering range
If the duty is corrosive instead of abrasive, a duplex or super-duplex grade such as UNS S32205 or SAF 2507, or a nickel alloy such as Incoloy 825, will serve better. Send the medium, temperature and pressure with the enquiry and the works will say which grade fits.
Applications for 1.4125 forgings
1.4125 is used wherever a part must resist wear and hold an edge or a dimension in a mildly corrosive environment: bearing races and balls, valve seats and stems, pump components, moulds and dies, gauge blocks, knives, cutlery and surgical instruments.
Bearings and rolling elements
Ball bearings, roller bearings and bearing races for corrosive or high-temperature duty where a through-hardened stainless race is required. ESR material is normal here.
Valve and pump components
Valve seats, seat rings, stems, bodies, bonnets, nozzles, plungers and wear rings: parts that see throttling wear and erosion in clean fluids.
Tooling, moulds and dies
Plastic mould cavities and inserts for corrosive polymers such as PVC, plus cold-work tooling, cutting dies and shear blades.
Measuring and precision parts
Gauge blocks, measuring instruments, pivot pins and spindles, where dimensional stability after sub-zero treatment matters more than toughness.
Cutlery and blades
Industrial knives, food-processing blades, slitting knives and high-end cutlery, and surgical and dental instruments to ASTM F899.
Wear parts
Bushings, sleeves, guide rails, wear rings and any component that must resist abrasion while staying stainless.
1.4125 forgings from Jiangyin Jiangnan Metal
Jiangyin Jiangnan Metal Co., Ltd. is an integrated melting works and open-die forge in Jiangyin, Jiangsu Province, China, operating since 1997. 1.4125 is melted, forged, heat-treated, machined and tested on one site, so a finished part traces back to its own melt number, not to a purchased billet.
The plant does not buy billet. Carbon, alloy, stainless and duplex grades are melted in a 25 t electric arc furnace, refined in 25 t and 50 t ladle furnaces and decarburised under vacuum where the chemistry requires it. For 1.4125 in particular, the 3 t and 6 t protective-atmosphere electroslag remelting furnaces are available where carbide size and cleanliness are critical, which is the usual requirement for bearing and precision work in this grade.
Forms supplied in 1.4125
Rings
Seamless rolled rings and forged rings: bearing races, valve seat rings, retaining rings and gear ring blanks, from OD 50 mm up to OD 6,000 mm on the 6 m radial-axial mill.
Bars and blocks
Forged round, square and flat bars, die blocks and mould blocks, supplied annealed with machining allowance or proof-machined.
Discs and blanks
Solid forged discs, plates and blanks to Ø5,000 mm machined, supplied proof-machined where ultrasonic examination is required.
Hollows and sleeves
Bored cylinders, sleeves, bushings and hollow bars to Ø1,600 × 10,000 mm on the CNC deep-hole drilling machine.
Valve and pump parts
Valve bodies, bonnets, seats, seat rings, stems and nozzles, as-forged or finish-machined to drawing.
Custom shapes
Shafts, spindles, pivot pins, wear rings and one-off profiles worked on 6,300 t, 4,000 t and 2,000 t presses; heaviest single piece 30 tonnes.
Delivery conditions, testing and certification
| Item | Detail |
|---|---|
| Delivery condition | Soft annealed (+A) to ≤ 285 HBW as standard; hardened and tempered to a specified HRC on request |
| Machining | As-forged with allowance, proof-machined for volumetric inspection, or finish-machined to drawing |
| Melt route | EAF + LF + VOD as standard; protective-atmosphere ESR available for clean-steel and bearing-quality requirements |
| Chemical analysis | Optical emission spectrometry (ASTM E415) and infrared carbon–sulphur analysis (ASTM E1019), verified at the furnace |
| Hardness | Portable Leeb testing to ASTM A956 converted per ASTM E140; bench Brinell or Rockwell arranged through an accredited laboratory when the specification requires it |
| Non-destructive examination | Ultrasonic to ASTM A388 / EN 10228-3 and magnetic particle to ASTM E709, in house |
| Metallography | Grain size to ASTM E112; carbide distribution assessment on request |
| Certification | EN 10204 3.1 mill test certificate as standard; EN 10204 3.2 witnessed by BV, DNV, LR, SGS, TÜV or the customer's own inspector on request |
| Approvals held | CCS · BV · DNV · LR · NK classification society approvals |
| Minimum order | 10 kg, with no minimum piece count |
| Lead time | 20–60 days from order confirmation; the upper end applies where ESR remelting is specified |
Traceability runs from the melt number through forging, heat treatment and machining to shipment. Because melting is on site, the chain does not begin at a purchased billet certificate.
Request a quotation for 1.4125
Send a drawing or a written specification to sales@steelforgepieces.com. Quotations for 1.4125 forgings are normally returned within two working days when the six items below are included in the first email.
| # | Item | Example |
|---|---|---|
| 1 | Grade and governing standard | 1.4125 / X105CrMo17 to EN 10088-3, or 440C to ASTM A473 |
| 2 | Dimensions, or a drawing (PDF, DWG, DXF, STEP) | OD 420 × ID 300 × H 90 mm rolled ring |
| 3 | Quantity and expected repeat volume | 24 pcs, about 3 × per year |
| 4 | Delivery condition | Annealed ≤ 285 HBW, proof-machined |
| 5 | Heat treatment, hardness and testing | Hardened and tempered to 58–60 HRC; UT to ASTM A388 |
| 6 | Certification and destination port | EN 10204 3.1 · Rotterdam |
Two details are worth stating explicitly for this grade, because both are decided at the melt and cannot be corrected later: whether ESR material is required, and whether the part is to be polished (calling for controlled low sulphur) or heavily machined (calling for the higher end of the sulphur range).
- Legal name
- Jiangyin Jiangnan Metal Co., Ltd.
- Business
- Integrated melting works, open-die forge & ring rolling mill
- Established
- 1997
- Employees
- 460, including 41 engineers and 140 technicians
- Plant address
- No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
- Telephone
- +86 189 2135 9659 · WhatsApp · WeChat
- Website
- www.steelforgepieces.com
- Melting
- EAF · LF · VOD · VIM · VAR · ESR · 60 t maximum heat
- Forging
- 6,300 t press · 6 m ring mill · 30 t maximum single piece
- Approvals
- CCS · BV · DNV · LR · NK
- Certification
- EN 10204 3.1 standard; 3.2 witnessed on request
- Minimum order
- 10 kg, no minimum piece count
- Lead time
- 20–60 days from order confirmation
- Export markets
- North America, Europe, Middle East, Asia-Pacific
- Business hours
- Monday–Saturday, 08:00–17:30 China Standard Time (UTC+8)
Frequently asked questions about 1.4125
Is 1.4125 the same as 440C?
Yes. 1.4125 (X105CrMo17) and AISI 440C (UNS S44004) are the same alloy under European and American designations, and both are covered by JIS SUS440C in Japan and 102Cr17Mo in China. The composition windows are effectively identical: 0.95–1.20 % carbon, 16.0–18.0 % chromium and 0.40–0.80 % molybdenum. The practical difference is which standard the mill certificate is issued against: EN 10088-3 for 1.4125, ASTM A276 or A473 for 440C. Name the standard you need on the order.
What hardness can 1.4125 reach?
1.4125 reaches 58–60 HRC after hardening from 1,010–1,070 °C and tempering below 400 °C, and at least 58 HRC as-quenched. That is the highest hardness obtainable from any standard stainless steel, and it comes from the 0.95–1.20 % carbon content. In the annealed delivery condition the steel is much softer: EN 10088-3 caps it at 285 HBW so that it can be machined.
What is the chemical composition of 1.4125?
To EN 10088-3:2023, grade X105CrMo17 (1.4125) contains 0.95–1.20 % carbon, a maximum of 1.00 % silicon, a maximum of 1.00 % manganese, a maximum of 0.040 % phosphorus, a maximum of 0.030 % sulphur, 16.0–18.0 % chromium and 0.40–0.80 % molybdenum, with iron as the balance. Nickel, nitrogen, copper and vanadium are not specified for this grade.
What is the Chinese equivalent of 1.4125?
The Chinese equivalent is 102Cr17Mo, the designation adopted in GB/T 1220-2007 and GB/T 20878-2007. The same steel was called 9Cr18Mo under the older GB/T 1220-1992, and both names still appear in circulation. It is the molybdenum-bearing development of 95Cr18 (9Cr18), with better hardness, wear resistance, tempering resistance and corrosion resistance than that grade.
At what temperature is 1.4125 forged?
Forge 1.4125 between 1,050 °C and 1,150 °C, and do not continue below about 900 °C. Heat slowly and preheat to 750–850 °C first, because this steel is crack-sensitive if the heating rate below 700 °C is too fast. After forging, cool slowly in a furnace or in insulating material, then anneal immediately, because air cooling a forging without annealing risks cracking. It also solidifies with coarse chromium-rich primary carbides and is prone to carbide banding, so the forging reduction and schedule matter to the finished part's service life.
Why must tempering between 425 °C and 565 °C be avoided?
Chromium carbides precipitate at the grain boundaries in that temperature range, depleting the surrounding matrix of the chromium that provides corrosion resistance. Impact toughness and corrosion resistance both fall sharply, and neither is recovered by further tempering at a lower temperature. Keep tempering below about 427 °C for the best corrosion resistance; some mills quote the band to avoid slightly wider, at 427–593 °C.
Is 1.4125 magnetic?
Yes. 1.4125 is ferromagnetic in every condition, annealed, hardened and tempered alike, because its structure is martensitic and not austenitic. Where a non-magnetic stainless steel is required, an austenitic grade such as 316L or a nitrogen-strengthened grade such as Nitronic 50 should be used instead.
How corrosion resistant is 1.4125?
Moderately. 1.4125 resists fresh water, steam, atmospheric exposure, petroleum products, alcohol, ammonia and foodstuffs, but it is not suitable for seawater, hot chloride solutions or reducing acids. Despite containing 16–18 % chromium, much of that chromium is tied up in carbides and unavailable for passivation, so 1.4125 is less corrosion resistant than lower-carbon martensitic grades such as 1.4057. Corrosion performance improves substantially with a fine polished surface, proper passivation and tempering below 427 °C.
Can 1.4125 be welded?
Welding is not recommended. The high carbon content makes the heat-affected zone hard and crack-prone. If a weld is unavoidable, preheat to about 260 °C, maintain that temperature throughout welding, and anneal at 730–760 °C for six to eight hours with a slow furnace cool immediately afterwards, never letting the part fall below 260 °C in between. Matching 440C filler is used where weld metal properties must match the parent steel. Single-piece open-die forgings avoid the problem entirely, which is why the grade is normally supplied that way.
What is the difference between 1.4125, 1.4112 and 1.4116?
All three are martensitic stainless steels, separated mainly by carbon content. 1.4125 (X105CrMo17) has 0.95–1.20 % C and gives the highest hardness and wear resistance. 1.4112 (X90CrMoV18) has 0.85–0.95 % C plus vanadium and slightly more chromium and molybdenum, trading a little hardness for finer carbides and better edge retention. 1.4116 (X50CrMoV15) has 0.45–0.55 % C, is significantly tougher and more corrosion resistant, and is the usual cutlery grade where the blade must survive impact. Choose 1.4125 for wear, 1.4116 for toughness.
In what forms does Jiangyin Jiangnan Metal supply 1.4125?
As open-die forgings and seamless rolled rings: forged rings and bearing races from OD 50 mm to OD 6,000 mm, round, square and flat bars, discs and blanks to Ø5,000 mm machined, hollow bars, sleeves and bored cylinders to Ø1,600 × 10,000 mm, die and mould blocks, and valve components including bodies, bonnets, seats, seat rings and stems. Parts are supplied as-forged with machining allowance, proof-machined for ultrasonic examination, or finish-machined to drawing. The heaviest single piece is 30 tonnes.
What is the minimum order quantity and lead time for 1.4125 forgings?
The minimum order is 10 kg, with no minimum piece count, so a single small part is quotable and so is a one-off large ring. Lead time runs 20 to 60 days from order confirmation. Standard melted-and-forged 1.4125 sits at the lower end; specifying electroslag remelted material, third-party witnessed inspection to EN 10204 3.2, or testing placed with an outside laboratory moves the date towards the upper end, Flag those requirements at enquiry stage, before the order is placed.
What certification is supplied with 1.4125 forgings?
An EN 10204 3.1 mill test certificate is supplied as standard, covering melt analysis, heat treatment, hardness and any non-destructive examination carried out. EN 10204 3.2 certificates witnessed by a classification society such as BV, DNV or LR, or by a third-party inspection body such as SGS or TÜV, are available on request. Because the steel is melted on site, the certificate traces the part back to its own melt number, not to a purchased billet. The works holds CCS, BV, DNV, LR and NK classification society approvals.
Standards and references
Composition and mechanical requirements on this page are taken from the current edition of EN 10088-3. Heat-treatment and physical-property figures are typical values compiled from mill datasheets for this grade and are given for guidance; order-specific values are confirmed on the mill certificate.
- EN 10088-3:2023, Stainless steels — Part 3: Technical delivery conditions for semi-finished products, bars, rods, wire, sections and bright products of corrosion resistant steels for general purposes. CEN, December 2023. Supersedes EN 10088-3:2014.
- EN 10088-1:2023, Stainless steels — Part 1: List of stainless steels. CEN.
- British Stainless Steel Association, Chemical composition of stainless steel long products to BS EN 10088-3.
- British Stainless Steel Association, Ambient temperature mechanical properties of martensitic and precipitation hardening stainless steel long products to BS EN 10088-3.
- ASTM A276/A276M, Standard Specification for Stainless Steel Bars and Shapes; ASTM A473, Standard Specification for Stainless Steel Forgings; ASTM F899, Standard Specification for Wrought Stainless Steels for Surgical Instruments.
- GB/T 1220 and GB/T 20878, Chinese national standards for stainless steel bars and grade designations (102Cr17Mo, formerly 9Cr18Mo).
- BGH Edelstahlwerke, 1.4125 / 1.4125 ESR (X105CrMo17) data sheet. Heat-treatment guideline values to DIN EN 10088-3.
- Lucefin Group, X105CrMo17 no. 1.4125 technical card. Physical properties and corrosion behaviour.
- Carpenter Technology, CarTech 440C Stainless data sheet. Annealing, hardening and tempering practice.
- Rolled Alloys, 440C Stainless data sheet. Forging and annealing practice.
Page last reviewed 22 September 2026 by the technical sales department of Jiangyin Jiangnan Metal Co., Ltd. Data is published for guidance and does not replace the standards it cites; only the analysis and test values recorded on the mill certificate for a given order are contractual.