# ASTM A182 F6NM Forgings, UNS S41500 / EN 1.4313 (X3CrNiMo13-4)

13Cr-4Ni-Mo martensitic stainless steel forged rings, seamless rolled rings, flanges,
round bars, shafts, sleeves, bushings, discs and tube sheets, open-die forged to drawing
by Jiangyin Jiangnan Metal Co., Ltd., Jiangyin, Jiangsu, China.

Canonical page: https://www.steelforgepieces.com/Stainless-Steel/A182-F6NM.html
Last updated: 30 September 2026

## F6NM key data

| Item | Value |
|---|---|
| Grade and UNS | ASTM A182 F6NM, UNS S41500 |
| Equivalents | EN 1.4313 (X3CrNiMo13-4), AISI 415, cast grade CA6NM |
| Type | Low carbon 13 % Cr, 4 % Ni, Mo martensitic stainless steel, air hardening |
| Tensile strength | 115 ksi [790 MPa] min |
| Yield strength, 0.2 % | 90 ksi [620 MPa] min |
| Elongation | 15 % min |
| Reduction of area | 45 % min |
| Hardness | 295 HBW max to ASTM; 23 HRC max for NACE MR0175 sour service |
| PREN | about 15, moderately corrosive chloride-free media |
| Service temperature | -60 C to 350 C (-76 F to 660 F) |
| Melting route | EAF + LF + VOD, ESR on request |
| Certification | EN 10204 3.1, or 3.2 with third-party witness |
| Pricing | Quoted per drawing, piece weight and heat treatment condition; no list price |

## What ASTM A182 F6NM is

ASTM A182 F6NM, UNS S41500, is a forging grade of low carbon martensitic stainless steel
with nominally 13 % chromium, 4 % nickel and 0.5 to 1.0 % molybdenum. The nickel and
molybdenum additions give sub zero notch ductility better than that of the standard 13Cr
grades 410 and 420 Mod, and the grade also welds well and resists corrosion in moderately
aggressive service. F6NM is air hardening, so heavy forged sections can be hardened with
little danger of cracking during heat treatment.

The grade is the forged counterpart of the cast grade CA6NM, and the same UNS S41500
composition is covered in bar form by ASTM A276. F6NM is accepted for sour service under
NACE MR0175 / ISO 15156-3 when the 23 HRC hardness limit and the related tempering
restrictions are satisfied.

## Chemical composition, percent by mass, ASTM A182/A182M grade F6NM

| Limit | C | Si | Mn | P | S | Cr | Ni | Mo | Fe |
|---|---|---|---|---|---|---|---|---|---|
| Min | - | - | 0.50 | - | - | 11.50 | 3.50 | 0.50 | Balance |
| Max | 0.05 | 0.60 | 1.00 | 0.030 | 0.030 | 14.00 | 5.50 | 1.00 | Balance |

Mill datasheets for the equivalent grade 1.4313 sometimes quote a narrower chromium band
of 12.0 to 14.0 %. Tighter internal ranges can be agreed at order stage.

## Mechanical properties, quenched and tempered

| Property | Requirement |
|---|---|
| Tensile strength, min | 115 ksi [790 MPa] |
| Yield strength, 0.2 % offset, min | 90 ksi [620 MPa] |
| Elongation in 2 in. [50 mm] or 4D, min | 15 % |
| Reduction of area, min | 45 % |
| Hardness | 295 HBW max |
| Hardness, NACE MR0175 / ISO 15156-3 | 23 HRC max |

The 23 HRC cap for sour service limits the strength that can be developed. NACE grade
F6NM is commonly restricted to about 75 ksi minimum yield, and about 85 ksi yield can be
reached with targeted cast chemistry and close control of tempering while still meeting
the hardness limit. Enquiries should state whether acceptance is to the ASTM condition or
the NACE condition, since the two are not the same. Charpy V-notch testing, for example at
-40 C (-40 F), is available as a supplementary requirement.

## Heat treatment

| Condition | Hardening | Tempering | Cooling |
|---|---|---|---|
| Standard ASTM, condition T | 1010 C min (1850 F min) | about 560 to 605 C (1040 to 1120 F) | Air or oil from hardening, air after temper |
| NACE MR0175 / ISO 15156-3 | 1010 C min (1850 F min) | Double temper, first about 650 to 690 C, second about 595 to 620 C | Air or oil from hardening, air after each temper |

The second temper required for sour service tempers the fresh martensite formed on cooling
from the first temper, which is what brings hardness reliably below 23 HRC. Cycles are set
according to section thickness and documented by furnace charts issued with the forgings.

## Equivalent grades

| System | Designation |
|---|---|
| ASTM, forgings | A182 F6NM |
| ASTM, bar | A276 and A479 grade S41500 |
| UNS | S41500 |
| EN and DIN | 1.4313, X3CrNiMo13-4, also written X2CrNiMo13-4 |
| AISI | 415 |
| Cast grade | CA6NM |
| Sour service listing | NACE MR0175 / ISO 15156-3, 23 HRC max |

Orders are accepted against X3CrNiMo13-4, UNS S41500, 1.4313 and Alloy 6NM to the same
drawing.

## Corrosion resistance and limits of use

At a PREN of about 15, F6NM gives useful service in moderately corrosive media free of
chlorides. Surface condition matters a great deal, and the same alloy performs better
polished than with a rough as-machined or as-forged surface. Where chlorides, seawater or
strong acids are involved, a duplex or super duplex grade such as A182 F51, F53 or F55, or
a nickel alloy such as Inconel 625, is the better choice.

## Where F6NM forgings are used

Valve bodies, bonnets, seats and seat rings, gates, wedges, stems and valve blocks for
ball, gate, globe, check and plug valves. Flanges, tube sheets, nozzles, forged pipe and
tube sections and fittings. Pump and compressor components, shafts, spindles, impeller
hubs, sleeves, bushings, discs and gear blanks. Hydro turbine runner components and the
related forged rings and shafts, as the wrought counterpart of CA6NM castings. Oil, gas
and petrochemical tubulars, wellhead and subsea components, and sour service parts held to
23 HRC max. Highly loaded parts needing low temperature toughness down to -60 C, including
locking and safety bolting. Tooling and mould blocks.

## Product forms

| Group | Items |
|---|---|
| Rings | Forged rings, seamless rolled rings, ring blanks, gear rings, retaining rings |
| Solid round | Round bars, shafts, eccentric shafts, spindles, stepped shafts, billets |
| Flat and disc | Discs, disks, blind blanks, tube sheets, plates, blocks |
| Hollow | Sleeves, bushings, hollow bars, forged tube and pipe, cylinders |
| Machined | Rough and finish machined forgings, valve parts, nozzles, manifolds |

Please state required dimensions and single piece weight so that feasibility can be
confirmed against press and ring mill capacity.

## Melting, testing and certificates

F6NM is melted by EAF plus LF plus VOD, with ESR available where cleanliness or
homogeneity requirements call for it. Forgings are ultrasonically examined to EN 10228-3,
SEP 1921 or ASTM A388 as specified, and supplied with inspection documents to EN 10204 3.1
or EN 10204 3.2 witnessed by a third party such as TUV, SGS, BV, LR or DNV. Options on
request include PMI, liquid penetrant and magnetic particle examination, hardness survey
for NACE compliance, low temperature Charpy testing, grain size determination,
intergranular corrosion testing and full traceability by heat number.

## Questions on A182 F6NM

**What is ASTM A182 F6NM?**
A forging grade of low carbon martensitic stainless steel with about 13 % chromium, 4 %
nickel and 0.5 to 1.0 % molybdenum, designated UNS S41500, used for valve bodies, seats
and gates, flanges, pump and compressor parts, hydro turbine components and oil and gas
forgings.

**How does F6NM differ from 410 stainless steel?**
Both are 13 % chromium martensitic stainless steels. F6NM is the low carbon version,
0.05 % C max, with nickel and molybdenum added, giving clearly better sub zero notch
ductility and weldability than 410 and 420 Mod along with somewhat better corrosion
resistance.

**Is F6NM the same as CA6NM?**
The chemistry is essentially the same 13Cr-4Ni-Mo. F6NM is the forged grade under
ASTM A182, UNS S41500, while CA6NM is the cast grade.

**Can F6NM be welded?**
Yes. Welding is normally carried out in the solution annealed or tempered condition with
suitable preheat, followed by post weld tempering. For sour service the post weld heat
treatment has to keep base metal and weld within 23 HRC, and procedure qualification
including weld hardness testing is required under NACE MR0175 / ISO 15156.

**Is A182 F6NM approved for sour service?**
Yes, subject to 23 HRC maximum hardness and the double tempering restrictions of
NACE MR0175 / ISO 15156-3. The requirement must be stated on the order.

**Which certificates come with the forgings?**
EN 10204 3.1 as standard, or EN 10204 3.2 with third-party endorsement on request,
traceable to the heat number.

**What is needed for a quotation?**
Drawing or dimensions, quantity, delivery condition (ASTM condition T or NACE double
tempered), any supplementary testing, certificate type and destination port.

## Manufacturer

Jiangyin Jiangnan Metal Co., Ltd., open-die forging factory
Address: No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Tel: 0086-189-2135-9659
Email: sales@steelforgepieces.com

Technical data follows ASTM A182/A182M and NACE MR0175 / ISO 15156-3 for grade F6NM,
UNS S41500, together with mill datasheets for EN 1.4313. Figures are for guidance and the
governing documents are the applicable edition of the standard and the agreed order
specification.