---
title: "1.4418 (X4CrNiMo16-5-1) Forgings"
description: "1.4418 / X4CrNiMo16-5-1 / S165M soft martensitic stainless steel: EN 10088-3 composition, +QT760 and +QT900 mechanical properties, physical properties, forging and heat-treatment windows, welding, corrosion behaviour and equivalents."
canonical: "https://www.steelforgepieces.com/Stainless-Steel/1.4418.html"
manufacturer: "Jiangyin Jiangnan Metal Co., Ltd."
address: "No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, 214423 China"
telephone: "+86 189 2135 9659"
email: "sales@steelforgepieces.com"
grade: "1.4418 / X4CrNiMo16-5-1 / S165M / SS 2387 / Z6CND16-05-01 / Z8CND17-04 / FE-PM3504"
standard: "EN 10088-3"
date_published: "2026-09-22"
date_modified: "2026-09-22"
license: "CC BY 4.0"
language: "en"
---

# 1.4418 (X4CrNiMo16-5-1) Forgings

Soft martensitic 16Cr-5Ni-1Mo stainless steel. Forged rings, bars, discs, shafts and
turbine parts, melted and forged at our own works in Jiangyin, Jiangsu Province, China.

**1.4418, steel name X4CrNiMo16-5-1, is a soft martensitic corrosion-resisting steel of
EN 10088-3 containing 15.0 to 17.0 % chromium, 4.0 to 6.0 % nickel and 0.80 to 1.50 %
molybdenum, with carbon held to 0.06 % maximum.** Holding the carbon that low is what
defines the grade: the martensite that forms on quenching is soft and tough, not hard
and brittle, so the steel reaches 900 to 1100 MPa tensile strength in the +QT900
condition while keeping 80 J of impact energy and weldability that most martensitic
stainless steels do not have.

**Jiangyin Jiangnan Metal Co., Ltd.**, an integrated melting works and open-die forging
factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province,
China, melts, forges, heat treats, machines and tests 1.4418 on one site and supplies it
with EN 10204 3.1 certification.

## Key figures

| Item | Value |
|---|---|
| EN number | 1.4418 |
| Steel name | X4CrNiMo16-5-1 |
| Rp0.2 min, +QT900, up to 160 mm | 700 MPa |
| Rm, +QT900 | 900 to 1100 MPa |
| KV min, +QT900, longitudinal, up to 160 mm | 80 J |
| PREN | 17.9 to 22.3 |
| Density | 7.7 kg/dm3 |
| Service range, DEW datasheet | -30 to 300 degrees Celsius |

## What is 1.4418, and what does "soft martensitic" mean?

Every martensitic stainless steel gets its strength the same way: heat it above the
transformation point, cool it fast, and the structure shears into martensite. How hard
and how brittle that martensite turns out is set almost entirely by carbon. In 1.4021
(X20Cr13) the carbon is 0.16 to 0.25 %, and the result is hard, strong and notch
sensitive. In 1.4418 the carbon ceiling is 0.06 %.

What is lost in carbon is put back as nickel. Four to six per cent nickel keeps the
structure fully martensitic on cooling despite the low carbon, and 0.80 to 1.50 %
molybdenum lifts pitting resistance. The steel that comes out is what the trade calls a
soft martensitic stainless: strong, but not hard and not brittle.

In the quenched and tempered condition the structure is not martensite alone. Valbruna
publishes roughly 80 % martensite, 10 % austenite and 10 % ferrite for 1.4418 in +QT900,
and the exact split moves with where the heat sits inside the chemistry band. The
austenite reverted during tempering is what carries the toughness: it is ductile at
temperatures where the martensite on its own would not be, and it is the reason both
specified tempering conditions sit above 550 degrees Celsius and not at the hardness
peak lower down.

That combination is what every application of the grade is built on:

- **Strength with toughness.** 700 MPa proof strength at 80 J impact energy is a
  combination the 13 % chromium grades cannot reach.
- **Weldability.** Low carbon means the heat-affected zone forms soft martensite. A
  welded joint in 1.4418 keeps most of its properties, which is why it is used for
  fabricated turbine runners.
- **Corrosion resistance close to 1.4301.** Normally the strength of a martensitic steel
  is bought at the cost of corrosion resistance. Here the chromium, nickel and
  molybdenum together put it close to austenitic 1.4301 in most media, and it is
  insensitive to intergranular corrosion.

## 1.4418 chemical composition

Cast analysis limits in per cent by mass from EN 10088-3. Balance iron.

| Limit | C | Si | Mn | P | S | Cr | Ni | Mo | N |
|---|---|---|---|---|---|---|---|---|---|
| Minimum | - | - | - | - | - | 15.0 | 4.0 | 0.80 | 0.020 |
| Maximum | 0.06 | 0.70 | 1.50 | 0.040 | 0.030 | 17.0 | 6.0 | 1.50 | - |

**The nitrogen entry is a minimum.** Nitrogen 0.020 % minimum is easy to read past,
because in almost every other stainless specification nitrogen appears as a ceiling. A
heat that is clean on nitrogen fails this grade. It is one reason a forging shop that
buys its billet in can be caught out on 1.4418.

### Why one datasheet says sulphur 0.030 % and another says 0.015 %

Both are right, for different product forms. EN 10088-3, which covers semi-finished
products, bars, rods, wire, sections and bright products, sets sulphur at 0.030 %
maximum. EN 10088-2, which covers sheet, plate and strip, sets 0.015 % maximum. A
forging is normally bought against Part 3.

EN 10088-3 also carries a footnote against the sulphur limit for this grade: a
controlled sulphur content of 0.015 % to 0.030 % is recommended and permitted where
machinability matters. That is a permission, not a default, and it points the wrong way
for a shaft.

It matters because sulphur is the element a customer is most likely to restrict below
the standard. Sulphides improve machinability and damage transverse toughness and
pitting resistance, and on a turbine or propeller shaft the transverse properties are
the ones that are being paid for. A restricted sulphur limit is set at the furnace and
cannot be corrected afterwards, so it belongs on the enquiry rather than on the purchase
order.

### Pitting resistance equivalent

PREN, calculated as %Cr + 3.3 x %Mo + 16 x %N, runs from 17.9 at the bottom of the
composition band to 22.3 at the top. That is a wide spread for one grade, and where a
heat lands inside it is an engineering variable, not a rounding error. Where the part is
going into brackish or intermittently wetted service, ask for the PREN to be aimed at
the upper half of the band and have it stated on the certificate.

## 1.4418 mechanical properties

EN 10088-3 specifies one annealed condition and two quenched and tempered conditions.
The number after QT is the minimum tensile strength in MPa, not a temperature.
Elongation and impact energy are longitudinal up to 160 mm and transverse above it.
Above 250 mm the values are agreed at enquiry.

| Condition | Diameter or thickness | Hardness HBW | Rp0.2 min | Rm | A min | KV min |
|---|---|---|---|---|---|---|
| +A annealed | all | 320 max | not specified | 1100 MPa max | not specified | not specified |
| +QT760 | up to 160 mm | not specified | 550 MPa | 760 to 960 MPa | 16 % longitudinal | 90 J longitudinal |
| +QT760 | over 160 up to 250 mm | not specified | 550 MPa | 760 to 960 MPa | 14 % transverse | 70 J transverse |
| +QT900 | up to 160 mm | not specified | 700 MPa | 900 to 1100 MPa | 16 % longitudinal | 80 J longitudinal |
| +QT900 | over 160 up to 250 mm | not specified | 700 MPa | 900 to 1100 MPa | 14 % transverse | 60 J transverse |

**Rm has a ceiling as well as a floor.** 900 to 1100 MPa is a band. A 1.4418 forging
that tests at 1150 MPa fails its certificate exactly as a forging at 880 MPa does, and
an over-strength result cannot be corrected by anything except re-tempering the whole
piece. This is the single most common cause of a 1.4418 rejection at certificate review,
and it is why the tempering temperature is chosen against the measured hardenability of
the heat and not set at a fixed number.

### Proof strength at elevated temperature

Minimum 0.2 % proof strength in MPa, EN 10088-3.

| Condition | 100 C | 150 C | 200 C | 250 C | 300 C |
|---|---|---|---|---|---|
| +QT760 | 520 | 510 | 500 | 490 | 480 |
| +QT900 | 660 | 640 | 620 | 600 | 580 |

The grade loses little strength across its working range: +QT900 still holds 580 MPa at
300 degrees Celsius, which is 83 % of its room-temperature minimum. The service ceiling
is set by the tempering temperature rather than by strength.

### Bright bar and small sections

Bright bar up to 10 mm in +QT900 is specified separately and runs higher, at 750 MPa
minimum proof strength and 900 to 1150 MPa tensile, with elongation dropping to 10 %.
Those values belong to drawn and ground bar, not to forgings, and they are listed here
only because a purchaser comparing a forging certificate against a bar datasheet will
otherwise see a mismatch and query it.

## Physical properties of 1.4418

| Property | Value |
|---|---|
| Density at 20 C | 7.7 kg/dm3 |
| Modulus of elasticity | 200 GPa at 20 C; 195 at 100 C; 185 at 200 C; 175 at 300 C; 170 at 400 C |
| Mean coefficient of thermal expansion from 20 C | 10.3 to 100 C; 10.8 to 200 C; 11.2 to 300 C; 11.6 to 400 C, all x10-6/K |
| Thermal conductivity at 20 C | 15 W/(m K) |
| Specific heat capacity at 20 C | 430 J/(kg K) |
| Electrical resistivity at 20 C | 0.80 ohm mm2/m |
| Magnetic behaviour | Ferromagnetic in every delivery condition |
| PREN | 17.9 to 22.3 |

**Which datasheet edition.** The values above are from the Deutsche Edelstahlwerke
Acidur 4418 datasheet. The current Swiss Steel edition of the same datasheet gives 0.70
ohm mm2/m for electrical resistivity and 10.8 x10-6/K for 20 to 100 C expansion instead.
Neither is wrong; they are different revisions. If your specification names one, say
which at enquiry.

Thermal conductivity of 15 W/(m K) is low, about half that of a 13 % chromium steel. On
a heavy section that shows up twice: the soak before forging takes longer per millimetre
of section than a carbon steel of the same size, and the quench produces a steeper
thermal gradient through the wall. Both are planned for at the quotation stage.

## Heat treatment and forging windows

| Operation | Temperature | Cooling | Purpose |
|---|---|---|---|
| Pre-heat before forging | slowly to above 800 C | not applicable | Brings the section up evenly before the fast heat |
| Soak for forging | 1150 to 1180 C | not applicable | Puts the whole section in the working range |
| Forging range | 1180 down to 950 C | furnace, dry ash or other controlled medium | Shapes the part; controlled cooling prevents quench cracks |
| General hot forming | 1150 down to 900 C | air | Rolling and lighter hot work |
| Soft annealing (+A) | 600 to 650 C | furnace or air | Softens to 320 HBW maximum for machining |
| Hardening | 950 to 1050 C | polymer, oil or air | Forms martensite through the section |
| Tempering for +QT760 | 590 to 620 C | water or air | Sets 760 to 960 MPa with 550 MPa proof strength |
| Tempering for +QT900 | 550 to 620 C | water or air | Sets 900 to 1100 MPa with 700 MPa proof strength |

**Which datasheet edition.** The temperatures above are from the Deutsche Edelstahlwerke
Acidur 4418 datasheet. The current Swiss Steel edition of the same sheet narrows two of
them: soft annealing at about 600 degrees Celsius and not above 625 degrees Celsius, and
hardening from 1000 to 1050 degrees Celsius. We work to whichever the order names.

### Why nothing is tempered between 450 and 550 C

Both conditions EN 10088-3 specifies temper at 550 degrees Celsius or above, and that is
deliberate. On the mill tempering diagram for this grade, hardness and tensile strength
peak at around 450 degrees Celsius while impact energy is at its lowest, and the useful
combination of strength with toughness only appears once the reverted austenite has
formed higher up. A forging tempered at 480 degrees Celsius would look strong on a
hardness tester and fail a Charpy test.

A part that will run warm in service is tempered above the band rather than into it, so
that service does not finish the tempering. And where a forging is tempered at the
bottom of the +QT900 range, near 550 degrees Celsius, the cool from tempering is
controlled, not left to drift down through the range below.

Some supplier datasheets describe 450 to 550 degrees Celsius as a temper embrittlement
range for this grade. We have not been able to source that wording to EN 10088-3 or to
the mill datasheet, so it is stated here as the range that is not used for tempering,
not as a standard requirement. The practical instruction is the same either way.

### Forging practice

1.4418 is rated as moderately forgeable, which is fair: harder work than a plain carbon
steel, easier than a free-machining grade with its narrow window. Getting a 1.4418
forging right comes down to the heating curve, the finishing temperature and the cool
afterwards.

- **The heating curve, not just the temperature.** Low thermal conductivity and a
  martensitic structure at room temperature mean a fast charge into a hot furnace puts
  the surface into tension against a cold core. The piece goes in slowly to above 800
  degrees Celsius, then up quickly to 1150 to 1180 degrees Celsius.
- **Finishing above 950 degrees Celsius.** Deformation below that leaves the steel stiff
  and the reduction goes into surface tearing instead of into the section. Heavy work is
  planned around reheats.
- **Controlled cooling after the last blow.** This grade air hardens. A heavy section
  left to cool in the yard becomes untempered martensite and can crack before it reaches
  the heat-treatment shop. The piece goes to the furnace or into dry ash.

Because the grade air hardens, the forging is annealed at 600 to 650 degrees Celsius
before rough machining and then hardened and tempered to the ordered condition. On heavy
sections we rough machine before the final heat treatment, so the quench reaches the
true wall thickness and the tensile test coupon represents the part and not an oversize
block.

## Welding 1.4418

Weldability is the practical argument for this grade over 1.4021 or 1.4057, and it is
the reason fabricated hydro turbine runners are built from it. The 0.06 % carbon ceiling
means the heat-affected zone transforms to soft martensite, which does not crack the way
a high-carbon martensitic heat-affected zone does. The steel is welded with all the
common processes.

- **Preheat 100 to 200 degrees Celsius**, held through the joint. The range is
  deliberately below the martensite start temperature.
- **No hydrogen or nitrogen in the shielding gas.** Argon or argon with a small helium
  addition. Hydrogen-bearing mixtures are excluded outright.
- **Filler 1.4430**, the austenitic 316L type, where the weld does not have to match the
  parent strength. Where it must match, a matching soft martensitic consumable is used
  and the assembly is heat treated afterwards.
- **Anneal or temper after welding.** Without it, the mechanical values in the weld
  metal and heat-affected zone can differ substantially from the parent metal, whatever
  the filler.

A note on sequence that saves arguments later: if the forging is supplied in +QT900 and
then welded without a post-weld cycle, the heat-affected zone is no longer in the
certified condition, and the certificate covers the forging as delivered, not the
fabrication. State the welding plan at enquiry and the tempering temperature can be set
above the post-weld cycle you intend to run.

## Corrosion resistance and service limits

1.4418 is more corrosion resistant than any plain martensitic stainless steel and is
broadly comparable with austenitic 1.4301 in most media. The molybdenum addition makes
limited marine use possible. It resists weak acids and alkalis, oxidising acids such as
nitric acid, and weakly chloride-bearing media, and it is insensitive to intergranular
corrosion.

**On stress corrosion cracking, the mill wording needs care.** The datasheet describes
1.4418 as resistant to fatigue corrosion and stress corrosion cracking, and against
austenitic grades in hot chlorides that holds. It is not a blanket immunity. This is a
martensitic steel running at 700 to 1100 MPa, and soft martensitic grades are
susceptible to sulphide stress cracking in wet H2S and to hydrogen embrittlement under
cathodic protection or after plating. If the duty involves H2S, cathodic protection or
electroplating, treat the hardness ceiling and the environment as design constraints and
state them at enquiry.

Laboratory tests with pure reagents on prepared specimens. Indicative, not a guarantee
for service.

| Medium | Concentration | Temperature | Behaviour |
|---|---|---|---|
| Sodium chloride solution | saturated | 20 C | Risk of pitting corrosion |
| Seawater | as found | 20 C | Risk of pitting corrosion |
| Steam | as found | 400 C | Resistant |
| Nitric acid | 7 % | 20 C | Resistant |
| Sulphuric acid | 1 % | 20 C | Resistant |
| Formic acid | 10 % | 20 C | Resistant |

The seawater line gets misquoted in both directions. A PREN of 17.9 to 22.3 is not a
seawater alloy: permanent stagnant immersion will pit it. It is also not a
freshwater-only alloy: propeller shafting, rudder stocks and pump shafts in flowing or
intermittently wetted seawater are among the grade's largest applications, because flow
and the absence of crevices keep pits from initiating. Where the duty is permanent
immersion, or where crevices under bearings and couplings cannot be designed out, the
correct step up is a duplex grade such as 1.4462.

### Service temperature

The Deutsche Edelstahlwerke datasheet gives minus 30 to plus 300 degrees Celsius. Other
mill sheets for the same grade quote higher upper limits, around 550 degrees Celsius and
in one case 600 degrees Celsius, so the figure is not settled across the industry. The
physical constraint is clear enough: the upper limit is set by the tempering
temperature, because running a part near its own tempering range over-tempers it and the
strength loss is permanent. Take 300 degrees Celsius as the conservative working figure
and confirm anything above it against the datasheet edition your specification names.

**EN 10088-3 specifies no sub-zero impact values for 1.4418.** The reverted austenite
does help at low temperature, and some databases quote toughness far below zero, but the
lowest test result we can point to on a published mill sheet is minus 40 degrees
Celsius. If the part has to be qualified below minus 30 degrees Celsius, the test
temperature and the acceptance energy are agreed at enquiry and tested on a coupon from
the same heat, not taken from a datasheet.

## Machining 1.4418

Machinability is rated as moderate and behaves like a structural steel of the same
hardness. The hardness is the variable that matters, not the fact that the steel is
stainless.

| Operation | Cutting speed | Depth of cut | Feed | Tool geometry |
|---|---|---|---|---|
| Drilling | 20 to 60 m/min | - | 0.03 to 0.11 mm/rev | 140 degree point angle |
| Turning | 35 to 95 m/min | 6 mm | 0.1 to 0.5 mm/rev | Rake 10 to 16 degrees, clearance 6 to 8 degrees, inclination -4 and 4 degrees |
| Milling | 80 to 175 m/min | - | 0.15 to 0.2 mm/tooth | - |

Machinability can be improved by a small sulphur addition up to 0.030 %, which is within
the EN 10088-3 limit. It is not free: the same sulphides cut corrosion resistance and
transverse mechanical properties. On a screw-machine part that trade is usually worth
making; on a turbine or propeller shaft it is not, and the sulphur is restricted
instead. Because the melting is on site, the aim is set before the heat rather than
measured after it.

1.4418 can also be nitrided, and it takes a polish, which matters for the sealing
surfaces on pump and centrifuge components.

## 1.4418 compared with the grades it competes against

| Property | 1.4418 | 1.4057 | 1.4542 (17-4 PH) | S41500 / F6NM | 1.4462 duplex |
|---|---|---|---|---|---|
| Steel name | X4CrNiMo16-5-1 | X17CrNi16-2 | X5CrNiCuNb16-4 | F6NM | X2CrNiMoN22-5-3 |
| Structure | Soft martensitic | Martensitic | Martensitic PH | Soft martensitic | Austenitic-ferritic |
| Carbon | 0.06 max | 0.12 to 0.22 | 0.07 max | 0.05 max | 0.030 max |
| Chromium | 15.0 to 17.0 | 15.0 to 17.0 | 15.0 to 17.0 | 11.5 to 14.0 | 21.0 to 23.0 |
| Nickel | 4.0 to 6.0 | 1.5 to 2.5 | 3.0 to 5.0 | 3.5 to 5.5 | 4.5 to 6.5 |
| Molybdenum | 0.80 to 1.50 | not specified | 0.60 max | 0.50 to 1.00 | 2.5 to 3.5 |
| Typical Rm | 900 to 1100 MPa | 800 to 950 MPa | 930 to 1310 MPa | 790 MPa min | 650 to 880 MPa |
| Weldability | Good | Poor | Good, needs re-solution | Good | Good |
| PREN | 17.9 to 22.3 | 15 to 19 | 16 to 17 | 13 to 17 | 31 to 38, typically 35 |
| Chosen when | Strength, toughness and water service together | Cost matters more than toughness | Highest strength, tunable by aging | An ASTM specification governs | Chloride corrosion governs, not strength |

Read the nickel and carbon columns together. 1.4057 has the same chromium as 1.4418 and
a quarter of the nickel, which is why it costs less and why it welds badly and runs
short on toughness. 17-4 PH reaches higher strength and is tunable through the aging
condition, but its PREN is lower and it is the wrong answer where water is the problem.
A182 F6NM is the grade ASTM-written projects actually specify, and it is a different
chemistry, not a translation of 1.4418: at 790 MPa minimum tensile it sits between
+QT760 and +QT900, on 13 % chromium against 16 %. 1.4462 is the step up when the duty is
chloride corrosion and not strength.

## 1.4418 equivalent designations

| System | Designation | Note |
|---|---|---|
| EN number | 1.4418 | EN 10088-1 and EN 10088-3 |
| EN name | X4CrNiMo16-5-1 | EN 10027-1 |
| Trade and legacy | S165M | Widely used in the United Kingdom and Scandinavia. Not an AISI type and not a valid UNS number, despite appearing as both |
| Sweden | SS 2387, SIS 2387 | The Swedish standard designation |
| France, AFNOR | Z6CND16-05-01 | Slightly tighter nickel and molybdenum than EN |
| France, aerospace | Z8CND17-04 | AIR 9160/C |
| EN aerospace | FE-PM3504 | EN 4627 and EN 4630 forgings, EN 4721 bar |
| Germany, superseded | X 4 CrNiMo 16 5, SEW 400 | Cited by material databases as comparable to SEW 400:1991-02. Confirm against the sheet before relying on it |
| ASTM, nearest cast | CB6, UNS J91804 | Cast 16Cr-4Ni, but molybdenum is capped at 0.50 % where 1.4418 requires 0.80 to 1.50 %. Nearest on chromium and nickel only. No exact wrought ASTM equivalent exists |
| ASTM, nearest wrought | UNS S41500, ASTM A182 F6NM | 13Cr-4Ni-Mo. A different chemistry, not a drop-in substitute |

**On the aerospace names.** EN 4627 covers hardened and tempered X4CrNiMo16-5-1 forgings
up to 200 mm at 1150 to 1300 MPa, EN 4630 covers forgings to 200 mm at 900 to 1050 MPa,
and EN 4721 covers air melted and electroslag remelted bar to 200 mm at 900 to 1050 MPa.
EN 4628 and EN 4631 cover the grade as well. These are separate acceptance regimes with
their own melt-route and testing requirements, not the EN 10088-3 grade with an
aerospace label on it. If the drawing cites one of them, say so at enquiry, because the
melt route is fixed before the ingot is cast.

## What we forge in 1.4418

Every item is forged from a single piece of steel melted on site, with no welding, no
casting and no purchased billet of unknown origin.

| Product family | 1.4418 parts | Used for |
|---|---|---|
| Seamless rolled rings | Rectangular and contoured rolled rings, gear ring blanks, slewing rings | Turbine and pump housings, bearing and seal seats |
| Forged rings | Upset and punched rings, retaining rings, seat rings | Sizes and sections outside the ring-mill envelope |
| Forged shafts | Pump shafts, propeller shafts, rudder stocks, spindles, stepped and gear shafts, piston rods | Hydro power, marine propulsion, process pumps |
| Forged bars and blocks | Round, square, flat and hexagonal bar, blocks and machining blanks | Machined valve parts, bolting, shear pins, tooling |
| Discs and blanks | Solid forged discs, covers, hubs, turbine runner blanks | Kaplan and Francis turbine components, centrifuge bowls |
| Hollow bars and sleeves | Bored hollow bar, sleeves, bushings, couplings, cylinders | Bearing housings, stern tube components, glands |
| Valve and wellhead parts | Valve bodies, bonnets, stems, seat rings, injector bodies | Water, steam and process valves, compressor parts |
| Centrifuge components | Decanter bowl bodies, hoods, covers, disc stack parts, conveyor hubs | Separators and decanter centrifuges |

### Works capability, Jiangyin Jiangnan Metal Co., Ltd.

| Parameter | Figure | Set by |
|---|---|---|
| Seamless rolled ring OD | 50 to 6,000 mm | 6 m, 3 m and 1 m radial-axial ring mills |
| Shaft length | up to 14,000 mm turned | Horizontal lathe; 15 m well furnace for vertical quench |
| Disc and tube sheet diameter | up to 5,000 mm machined | 5,000 mm swing vertical turning lathe |
| Bored cylinder | up to 1,600 x 10,000 mm | CNC deep-hole drilling machine |
| Single-piece weight | 10 to 30,000 kg | 60 t maximum heat size; 6,300 t press |
| Hydraulic presses | 6,300 t, 4,000 t, 2,000 t | Cogging, upsetting, discs and blocks |
| Melting | EF, LF, VOD, IF, VIM, VAR and ESR on site | 60 t maximum heat |
| Heat treatment | 14 furnaces | Annealing, hardening, tempering, vertical quench |
| Approvals | CCS, BV, DNV, LR, NK | Classification society approvals held by the works |
| Certification | EN 10204 3.1 and 3.2 | 3.2 witnessed by a third party on request |
| Minimum order | 10 kg | No minimum piece count |
| Lead time | 20 to 60 days | From order confirmation, grade dependent |

Delivery condition is +QT900 as standard unless the order says otherwise, supplied as
forged with an agreed allowance, rough machined for volumetric inspection, or finish
machined to drawing. Anti-rust coating and seaworthy packing are included for export.

## How a 1.4418 order runs through the works

1. **Melting and ladle refining.** Steel is melted in the electric arc furnace, refined
   in the ladle furnace and decarburised under vacuum. VOD is the step that matters on
   this grade: it takes carbon to the 0.06 % ceiling while holding chromium, and it
   allows nitrogen to be set at or above the 0.020 % minimum instead of hoped for.
   Maximum heat size is 60 t.
2. **Chemistry verified at the furnace.** Cast analysis by optical emission spectrometry
   to ASTM E415 and infrared carbon and sulphur analysis to ASTM E1019. On 1.4418 the
   carbon, nitrogen and sulphur readings decide whether the heat is released.
3. **Forging.** Pre-heat slowly to above 800 degrees Celsius, soak at 1150 to 1180
   degrees Celsius, work on the 6,300 t, 4,000 t or 2,000 t press finishing above 950
   degrees Celsius. Rings are punched and expanded over a saddle mandrel or rolled on
   the 6 m, 3 m or 1 m mill. The piece is then cooled in the furnace or in dry ash.
4. **Annealing.** 600 to 650 degrees Celsius in the heat-treatment shop, which holds 14
   furnaces, before rough machining.
5. **Rough machining.** Heavy sections are rough machined before final heat treatment so
   the quench reaches the true wall thickness and the test coupon represents the part.
6. **Hardening and tempering.** 950 to 1050 degrees Celsius, quenched in polymer, oil or
   air; tempered at 550 to 620 degrees Celsius for +QT900 or 590 to 620 degrees Celsius
   for +QT760. Long shafts are quenched vertically in one of the two 15 m well furnaces
   to control distortion. Furnace charts are issued with the certificate.
7. **Testing.** Tensile testing to ISO 6892 and ASTM A370 on 600 kN and 300 kN machines,
   Charpy V-notch impact with a low-temperature bath to minus 60 degrees Celsius,
   Brinell hardness, and metallography where the order calls for it.
8. **Non-destructive examination and certification.** Ultrasonic examination to EN
   10228-3 or ASTM A388, magnetic particle examination to ASTM E709, then an EN 10204
   3.1 inspection certificate, or 3.2 witnessed by BV, DNV, LR, SGS, TUV or the
   customer's own inspector.

## Standards referenced

| Standard | Title | Role |
|---|---|---|
| EN 10088-3 | Stainless steels, Part 3: technical delivery conditions for semi-finished products, bars, rods, wire, sections and bright products | Defines 1.4418, its chemistry and its property levels |
| EN 10088-1 | Stainless steels, Part 1: list of stainless steels | Grade list and physical property values |
| EN 10088-2 | Stainless steels, Part 2: sheet, plate and strip | Source of the 0.015 % sulphur limit quoted on some datasheets |
| EN 10250-4 | Open die steel forgings for general engineering purposes, Part 4: stainless steels | The EN product standard for an open-die stainless forging |
| EN 10272 | Stainless steel bars for pressure purposes | Where the part is pressure retaining |
| EN 10027-1 | Designation systems for steels, Part 1: steel names | The name X4CrNiMo16-5-1 |
| EN 4627, EN 4630, EN 4721 | Aerospace series, steel X4CrNiMo16-5-1, hardened and tempered forgings and bar | Aerospace acceptance, separate melt-route and testing requirements |
| AIR 9160/C | French aerospace material specification | Z8CND17-04 |
| EN 10204 | Metallic products, types of inspection documents | 3.1 as standard, 3.2 with a third-party witness |
| EN 10228-3 | Non-destructive testing of steel forgings, Part 3: ultrasonic testing of ferritic or martensitic steel forgings | Internal soundness, the correct part for this grade |
| ASTM A388 | Ultrasonic examination of heavy steel forgings | Alternative ultrasonic acceptance where the order calls for it |
| ISO 6892-1, ASTM A370 | Tensile testing of metallic materials | Mechanical test methods |

**EN 10088-3 does not cover forgings.** Its scope is semi-finished products, hot or cold
formed bars, rods, wire, sections and bright products, and it states that it does not
apply to components manufactured by further processing of those forms. It defines the
grade, the chemistry and the property levels, and a forging is certified against those
levels in practice, but the product standard for an open-die stainless forging is EN
10250-4. Tell us which one the drawing calls for, because the acceptance requirements
are not the same.

## What to send with a 1.4418 enquiry

| Item | Why it changes the quotation |
|---|---|
| Specification and edition | EN 10088-3, EN 10250-4, EN 10272 or an aerospace standard; the acceptance regimes differ |
| Delivery condition | +A, +QT760 or +QT900. +QT900 is the usual choice |
| Drawing or rough dimensions | Sets the input weight, which dominates cost |
| Ruling section | Decides whether longitudinal or transverse acceptance values apply, and whether the piece is above 250 mm where values are agreed |
| Machining state | As forged, rough machined for ultrasonic testing, or finish machined to drawing |
| Restricted sulphur or aimed PREN | Set at the furnace and impossible to correct afterwards |
| Impact requirement and test temperature | EN 10088-3 specifies no sub-zero values; anything below minus 30 C is agreed and tested |
| Planned welding or post-weld heat treatment | Sets the tempering temperature so properties survive your fabrication |
| Non-destructive examination | EN 10228-3 or ASTM A388 class, plus magnetic particle requirements |
| Inspection document and destination | EN 10204 3.1, or 3.2 with the named inspection body, and the port |

Minimum order is 10 kg with no minimum piece count. Lead time normally runs 20 to 60
days. 1.4418 needs no remelting step for general engineering work, so it sits at the
lower end of that range unless an aerospace melt route or third-party inspection has to
be scheduled.

## 1.4418 questions and answers

**What is 1.4418 steel?**

1.4418, steel name X4CrNiMo16-5-1, is a soft martensitic corrosion-resisting steel of EN
10088-3 containing 15.0 to 17.0 % chromium, 4.0 to 6.0 % nickel and 0.80 to 1.50 %
molybdenum, with carbon capped at 0.06 %. The low carbon content produces a soft, tough
martensite instead of the hard brittle martensite of the classic 13 % chromium grades,
so the steel combines 900 to 1100 MPa tensile strength in the +QT900 condition with
impact toughness of 80 J and corrosion resistance close to that of austenitic 1.4301. It
is widely known in trade as S165M and in Sweden as SS 2387.

**What is the chemical composition of 1.4418?**

Per EN 10088-3, cast analysis in per cent by mass: carbon 0.06 maximum, silicon 0.70
maximum, manganese 1.50 maximum, phosphorus 0.040 maximum, sulphur 0.030 maximum,
chromium 15.0 to 17.0, nickel 4.0 to 6.0, molybdenum 0.80 to 1.50, nitrogen 0.020
minimum, balance iron. Nitrogen carries a minimum, not a maximum. That is unusual, and
it is easy to miss when a heat is bought in.

**What is the difference between 1.4418 +QT760 and +QT900?**

Only the tempering temperature. +QT760 is tempered at 590 to 620 degrees Celsius and
gives 550 MPa minimum proof strength, 760 to 960 MPa tensile strength and 90 J minimum
impact energy in sections up to 160 mm. +QT900 is tempered at 550 to 620 degrees Celsius
and gives 700 MPa minimum proof strength, 900 to 1100 MPa tensile strength and 80 J
minimum impact energy in the same section. +QT900 is the condition most of the market
buys. Note that both have an upper tensile limit, so an over-strength forging is
rejected just as a weak one is.

**Is 1.4418 the same as S165M, SS 2387 and Z8CND17-04?**

They describe the same steel but not through the same document. S165M is a trade and
legacy designation common in the United Kingdom and Scandinavia, and despite being
written as AISI S165M or UNS S165M by some suppliers it is not an AISI type and not a
valid UNS number. SS 2387 is the Swedish standard designation. Z6CND16-05-01 is the
AFNOR name and Z8CND17-04 is the French aerospace name under AIR 9160, also carried by
EN aerospace standards as FE-PM3504. The limits are close but not identical, so the
purchase order should name one document and one edition.

**Is there an ASTM or UNS equivalent of 1.4418?**

There is no exact one. The nearest cast grade in the ASTM system is CB6, UNS J91804, at
roughly 16 % chromium and 4 % nickel, although CB6 caps molybdenum at 0.50 % where
1.4418 requires 0.80 to 1.50 %, so it matches on chromium and nickel only. The soft
martensitic grade that United States specifications actually use is UNS S41500, sold as
ASTM A182 F6NM and cast as CA6NM, but that is a 13Cr-4Ni-Mo chemistry with lower
chromium, lower nickel and lower molybdenum than 1.4418, and it is not a drop-in
substitute. Where a project is written to ASTM, the practical route is to supply to EN
10088-3 with an EN 10204 3.1 certificate and a written comparison of the two chemistries
for the purchaser to approve.

**At what temperature is 1.4418 forged?**

The billet is heated slowly to above 800 degrees Celsius, then raised more quickly to
1150 to 1180 degrees Celsius, and worked between 1180 and 950 degrees Celsius. General
hot forming is quoted as 1150 down to 900 degrees Celsius. After the last blow the piece
is cooled in the furnace, in dry ash or in another controlled medium, never in still air
on a heavy section, because 1.4418 air hardens and an uncontrolled cool leaves
untempered martensite and quench cracks.

**What heat treatment does 1.4418 need?**

Soft annealing at 600 to 650 degrees Celsius with a furnace or air cool. Hardening from
950 to 1050 degrees Celsius quenched in polymer, oil or air. Tempering at 590 to 620
degrees Celsius for +QT760 or 550 to 620 degrees Celsius for +QT900, cooled in water or
air. Nothing is tempered between 450 and 550 degrees Celsius: hardness peaks there while
impact energy is at its lowest, which is why both specified conditions temper at 550
degrees Celsius or above. The current Swiss Steel edition of the mill datasheet narrows
annealing to about 600 degrees Celsius and not above 625, and hardening to 1000 to 1050
degrees Celsius.

**Can 1.4418 be welded?**

Yes, and weldability is the main reason this grade exists. The carbon maximum of 0.06 %
means the weld and heat-affected zone transform to soft martensite, not the hard brittle
martensite of 1.4021 or 1.4057. All common processes are used. Preheat of 100 to 200
degrees Celsius, which is below the martensite start temperature, is recommended,
shielding gases containing hydrogen or nitrogen are avoided, and the standard filler is
1.4430, the austenitic 316L type. Without a post-weld anneal or temper the properties in
the weld and the heat-affected zone can differ substantially from the parent metal, so
the joint is annealed or tempered afterwards.

**How corrosion resistant is 1.4418, and can it be used in seawater?**

Its PREN is 17.9 to 22.3, better than any plain martensitic stainless steel and broadly
comparable to austenitic 1.4301 in most media, but below the threshold for permanent
seawater immersion. Laboratory data show it resistant to 7 % nitric acid, 1 % sulphuric
acid and 10 % formic acid at 20 degrees Celsius and to steam at 400 degrees Celsius,
while saturated sodium chloride solution and seawater at 20 degrees Celsius both carry a
risk of pitting. It is insensitive to intergranular corrosion. Marine service is
therefore normal for shafting in flowing or intermittently wetted conditions and not
advised for permanent stagnant immersion. For that, a duplex grade such as 1.4462 is the
correct step up. The mill datasheet also describes the grade as resistant to fatigue
corrosion and stress corrosion cracking, which holds against austenitic grades in hot
chlorides but is not a blanket immunity: this is a martensitic steel at 700 to 1100 MPa,
and soft martensitic grades are susceptible to sulphide stress cracking in wet hydrogen
sulphide and to hydrogen embrittlement under cathodic protection or after plating.

**Is 1.4418 magnetic?**

Yes. The structure after quenching and tempering is tempered martensite with stabilised
austenite and a small amount of ferrite, and the steel is ferromagnetic in every
delivery condition. That rules it out where a non-magnetic part is required, and it
means magnetic particle examination can be used on it for surface inspection.

**What is the service temperature range of 1.4418?**

The Deutsche Edelstahlwerke datasheet gives minus 30 to plus 300 degrees Celsius. Other
mill sheets for the same grade quote higher upper limits, around 550 and in one case 600
degrees Celsius, so treat 300 as the conservative working figure and confirm anything
above it against the datasheet edition your specification names. The upper limit exists
because running a part near its own tempering range over-tempers it, and that strength
loss is permanent. At the cold end, EN 10088-3 specifies no sub-zero impact values for
this grade. The reverted austenite does help, and some databases quote toughness far
below zero, but the lowest test result on a published mill sheet is minus 40 degrees
Celsius. Anything below minus 30 degrees Celsius is agreed at enquiry and tested on a
coupon from the same heat.

**Why does one 1.4418 datasheet say sulphur 0.030 % and another 0.015 %?**

Because they quote different parts of EN 10088. Part 3, which covers semi-finished
products, bars, rods, wire, sections and bright products and is the part a forging is
normally bought against, sets sulphur at 0.030 % maximum. Part 2, which covers sheet,
plate and strip, sets 0.015 % maximum. Both are correct for their own product form. If a
drawing simply says EN 10088 without a part number and the sulphur limit matters, the
limit has to be settled before the heat is melted, not argued about at goods inward.

**Who supplies 1.4418 forgings in China, and in what sizes?**

Jiangyin Jiangnan Metal Co., Ltd. forges 1.4418 / X4CrNiMo16-5-1 at No.1 Chengxiqiao
Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. The works has operated
since 1997, melts its own steel with a 60 t maximum heat size, and runs 6,300 t, 4,000 t
and 2,000 t hydraulic presses, 6 m, 3 m and 1 m radial-axial ring mills and 14
heat-treatment furnaces. Seamless rolled rings run to 6,000 mm outside diameter, discs
and tube sheets machine to 5,000 mm diameter, shafts turn to 14,000 mm and single-piece
weight reaches 30,000 kg. Contact sales@steelforgepieces.com or +86 189 2135 9659.

**What certification is supplied with 1.4418 forgings?**

An EN 10204 3.1 inspection certificate as standard, traceable to the melt number,
reporting cast analysis, proof and tensile strength, elongation, impact energy, hardness
and heat-treatment records. EN 10204 3.2 witnessed by BV, DNV, LR, SGS, TUV or the
customer's own inspector is available on request. Ultrasonic examination is carried out
to EN 10228-3, the part written for ferritic and martensitic forgings, or to ASTM A388
where the order calls for it, with magnetic particle examination to ASTM E709 available
because the grade is ferromagnetic. The works holds CCS, BV, DNV, LR and NK
classification society approvals.

## Glossary

**Soft martensitic stainless steel.** A martensitic stainless steel with carbon held
very low, typically 0.06 % or less, and nickel added to keep the structure martensitic.
The martensite that forms is tough and weldable, not hard and brittle. 1.4418 and F6NM
are the two grades most often meant by the term.

**+A, annealed.** Heat treatment condition symbol of EN 10088-3. For 1.4418 it means 600
to 650 degrees Celsius with a furnace or air cool, giving 320 HBW maximum.

**+QT760 and +QT900.** Quenched and tempered to a minimum tensile strength of 760 MPa or
900 MPa. The number is the bottom of the tensile band, not a temperature. Both
conditions also carry an upper tensile limit.

**Rp0.2, Rm, A and KV.** 0.2 % proof strength, tensile strength, elongation after
fracture and Charpy V-notch absorbed energy. Longitudinal values are measured along the
grain flow, transverse values across it.

**Stabilised austenite.** Finely dispersed austenite that precipitates during tempering
above about 500 degrees Celsius and reaches a maximum near 610 degrees Celsius. It is
the reason a soft martensitic steel keeps its toughness at low temperature.

**Temper embrittlement.** Loss of toughness caused by tempering in, or slow cooling
through, a particular temperature band. For 1.4418 that band is 450 to 550 degrees
Celsius.

**PREN.** Pitting resistance equivalent number, %Cr + 3.3 x %Mo + 16 x %N. A screening
index for chloride pitting resistance, not a service prediction.

**Cast analysis and product analysis.** Cast analysis is taken from the liquid steel and
is what the EN 10088-3 limits apply to. Product analysis is taken from the finished
product and may deviate by the tolerances given in the standard.

**Ruling section.** The governing thickness or diameter of the piece, which decides
which row of the property table applies and whether the acceptance values are
longitudinal or transverse.

**EN 10204 3.1 and 3.2.** A 3.1 inspection certificate is issued by the manufacturer's
inspection department, independent of production. A 3.2 certificate is also validated by
the purchaser's inspector or an inspection body named in the order.

## Summary of supply

- Jiangyin Jiangnan Metal Co., Ltd. is an integrated steel melting works and open-die
  forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu
  Province, 214423 China, operating since 1997.
- Jiangyin Jiangnan Metal Co., Ltd. produces 1.4418 / X4CrNiMo16-5-1 forged bars,
  seamless rolled rings, forged rings, discs, blocks, shafts, hollow bars, sleeves,
  bushings, valve parts, turbine components and centrifuge bowl parts.
- 1.4418 forgings from Jiangyin Jiangnan Metal Co., Ltd. are supplied to EN 10088-3
  property levels in the +A, +QT760 or +QT900 condition, and against EN 10250-4 where
  the drawing calls for the open-die forging product standard.
- 1.4418 in +QT900 from Jiangyin Jiangnan Metal Co., Ltd. meets 700 MPa minimum 0.2 %
  proof strength, 900 to 1100 MPa tensile strength, 16 % minimum elongation and 80 J
  minimum Charpy V-notch energy in sections up to 160 mm.
- 1.4418 forgings from Jiangyin Jiangnan Metal Co., Ltd. are forged between 1180 and 950
  degrees Celsius, hardened from 950 to 1050 degrees Celsius, tempered at 550 to 620
  degrees Celsius for +QT900, and ultrasonically tested to EN 10228-3 or ASTM A388.
- Single-piece forging weight at Jiangyin Jiangnan Metal Co., Ltd. runs from 10 kg to
  30,000 kg, seamless rolled rings from 50 mm to 6,000 mm outside diameter, and shafts
  to 14,000 mm turned length.
- Jiangyin Jiangnan Metal Co., Ltd. employs 460 people including 9 senior engineers, 32
  intermediate engineers and 140 technicians, and holds CCS, BV, DNV, LR and NK
  classification society approvals.
- Minimum order for 1.4418 at Jiangyin Jiangnan Metal Co., Ltd. is 10 kg with no minimum
  piece count, and normal lead time is 20 to 60 days from order confirmation.
- Enquiries reach Jiangyin Jiangnan Metal Co., Ltd. at sales@steelforgepieces.com or +86
  189 2135 9659.

## Data sources and reuse

This page is published by Jiangyin Jiangnan Metal Co., Ltd. and reviewed by its
metallurgy department. The technical data on it may be reused under CC BY 4.0 with
attribution.

- EN 10088-3, chemical composition and mechanical property tables for X4CrNiMo16-5-1,
  including the elevated-temperature proof strength values.
- EN 10088-1 and EN 10088-2, grade list, physical property values and the sheet, plate
  and strip sulphur limit.
- Deutsche Edelstahlwerke material datasheet Acidur 4418 for 1.4418 / X4CrNiMo16-5-1,
  document 2015-0028: physical properties, heat treatment and hot-forming temperatures,
  forging practice, welding practice, corrosion data and cutting conditions. Where the
  current Swiss Steel edition of the same sheet differs, the difference is noted in the
  text.
- EN 4627, EN 4630 and EN 4721, aerospace acceptance regimes for X4CrNiMo16-5-1 forgings
  and bar.
- Valbruna Nordic datasheet for 1.4418 in +QT900: phase balance of the quenched and
  tempered structure.
- Works records of Jiangyin Jiangnan Metal Co., Ltd. for plant capability, production
  route and inspection scope.

Cite this page as:

    Jiangyin Jiangnan Metal Co., Ltd. (2026). "1.4418 (X4CrNiMo16-5-1) Forgings."
    Jiangyin, Jiangsu, China.
    https://www.steelforgepieces.com/Stainless-Steel/1.4418.html
    Last reviewed 22 September 2026.

Values on this page are for reference. They do not replace the current edition of the
applicable standard or the agreed purchase order, and should be confirmed against the
governing specification before design use.

## Contact

Jiangyin Jiangnan Metal Co., Ltd. Integrated melting works and open-die forging factory,
established 1997 No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province
214423, China Telephone, WhatsApp and WeChat: +86 189 2135 9659 Email:
sales@steelforgepieces.com Business hours: Monday to Saturday, 08:00 to 17:30 China
Standard Time

The works is in Zhouzhuang Town, in the east of Jiangyin City, on the south bank of the
Yangtze between Shanghai and Nanjing. Wuxi Shuofang International Airport is 30 km away
and the Shanghai airports are 160 km. The nearest export ports are Zhangjiagang and
Shanghai. Customer audits, pre-shipment inspection and third-party witness testing are
welcome.