1. The one-line answer, then the caveat
Yes — 1.4057, X17CrNi16-2, AISI 431, UNS S43100, 431S29, Z15CN16-02, SUS 431, 14Kh17N2 and 1Cr17Ni2 all describe a nickel-bearing martensitic stainless steel of roughly 16 % chromium and 2 % nickel. Substituting one for another is normal industrial practice and works most of the time.
The caveat is what this article is about. "Equivalent" in a cross-reference table means the grades were written to do the same job. It does not mean the numeric limits are identical. Seven standards bodies wrote seven slightly different specifications, at different times, for different national industries. The carbon bands differ by 0.05 %. The chromium minimums differ by a full point. The nickel bands differ by enough that two of them barely overlap.
For most general engineering work, none of that matters. It starts to matter when a mill certificate crosses a border — when a European buyer accepts a Chinese or Russian heat against an EN order, when a UK end user inspects an American-sourced shaft, or when a third-party inspector checks a certificate line by line before signing an EN 10204 3.2. That is where a heat that is genuinely fit for purpose gets rejected on paper.
Who this is for
Specifying engineers and procurement teams writing purchase orders for martensitic stainless bar, ring or forging where the mill, the designer and the end user are not all in the same standards system. If you are looking for the material's properties and applications rather than its designations, start with our 1.4057 / X17CrNi16-2 forged steel parts technical page instead.
2. Where the bands actually diverge
Four of the seven elements are effectively harmonised: silicon, manganese, phosphorus and sulphur limits are close enough across the standards that no realistic heat will pass one and fail another. All the disagreement sits in three elements — carbon, chromium and nickel — and that is where a specification conflict comes from.
Below, each of those three elements is plotted on a single scale with all seven specified bands stacked against it. The dashed line is a plausible heat analysis. Bars the line crosses are in specification; bars it misses are not.
Figure 1 — Specified composition bands, seven standards
Same steel, seven ranges. The dashed line is one heat analysis tested against all of them.
GOST and GB stop at 0.17 % — the EN band runs 0.05 % higher.
A heat at the bottom of the EN chromium band is below the GOST and GB minimum.
The British band sits almost entirely above the American one — the widest single divergence in this grade.
Bands compiled from published editions of EN 10088-3, ASTM A276, BS 970-1, NF A35-573, JIS G4303, GOST 5632 and GB/T 1220. Standards are revised; verify against the edition named on your order before use.
Read the nickel chart again, because it is the one that catches people. A heat analysed at Ni 1.62 % is comfortably inside EN, ASTM, AFNOR, JIS, GOST and GB limits. It is 0.38 % below the BS 431S29 minimum. Nothing is wrong with the steel. It simply was not melted to a British specification, and if the drawing says 431S29 the certificate will not clear.
3. Full composition comparison, all seven systems
The complete picture, including the four harmonised elements. Values in weight percent; single figures are maximums.
| Designation | Standard | C | Si | Mn | P | S | Cr | Ni |
|---|---|---|---|---|---|---|---|---|
| 1.4057 / X17CrNi16-2 | EN 10088-3 | 0.12–0.22 | 1.00 | 1.50 | 0.040 | 0.030 | 15.0–17.0 | 1.50–2.50 |
| AISI 431 / S43100 | ASTM A276 | 0.20 max | 1.00 | 1.00 | 0.040 | 0.030 | 15.0–17.0 | 1.25–2.50 |
| 431S29 | BS 970 Part 1 | 0.12–0.20 | 1.00 | 1.00 | 0.040 | 0.030 | 15.0–18.0 | 2.00–3.00 |
| Z15CN16-02 | NF A35-573 | 0.12–0.20 | 1.00 | 1.00 | 0.040 | 0.030 | 15.0–17.0 | 1.50–2.50 |
| SUS 431 | JIS G4303 | 0.20 max | 1.00 | 1.00 | 0.040 | 0.030 | 15.0–17.0 | 1.25–2.50 |
| 14Х17Н2 / 14Kh17N2 | GOST 5632 | 0.11–0.17 | 0.80 | 0.80 | 0.030 | 0.025 | 16.0–18.0 | 1.50–2.50 |
| 14Cr17Ni2 (ex 1Cr17Ni2) | GB/T 1220 | 0.11–0.17 | 0.80 | 0.80 | 0.035 | 0.030 | 16.0–18.0 | 1.50–2.50 |
Values shown in red diverge materially from the EN 10088-3 reference row. GOST and GB additionally cap titanium at about 0.20 % and copper at about 0.30 %, which EN and ASTM do not specify.
What the divergences tell you metallurgically
These are not arbitrary. The GOST-derived pair — 14Kh17N2 and its Chinese descendant — deliberately trade a narrower carbon window and a higher chromium floor for better corrosion behaviour and tighter property scatter, at the cost of a slightly lower attainable hardness. The British grade's higher nickel floor pushes the alloy further from the delta-ferrite field, which matters most in the heavy sections the UK marine and defence industries specified it for. The wider EN carbon band is the most production-friendly of the seven, which is part of why European mills consolidated on it.
If you want the consequences of those choices rather than the numbers — hardenability, sour service limits, cryogenic toughness, weldability — that ground is covered on our X17CrNi16-2 forgings reference page.
4. Three heats, three different verdicts
Abstract limits are easy to nod at and hard to act on. Here are three plausible ladle analyses, each checked against all seven specifications. Every one of them is a perfectly serviceable heat of this steel. Every one of them fails at least one standard.
Heat A — European mill
C 0.195 · Cr 16.2 · Ni 2.10
- EN 1.4057 ✓
- ASTM 431 ✓
- 431S29 ✓
- Z15CN16-02 ✓
- SUS 431 ✓
- 14Kh17N2 ✗
- 14Cr17Ni2 ✗
Carbon at 0.195 % clears the 0.20 % ASTM ceiling with almost nothing to spare and sits 0.025 % above the GOST and GB maximum. Perfectly normal European practice; not acceptable on a Russian or Chinese domestic specification. Note also how little margin remains against ASTM — a re-check analysis at 0.203 % would fail.
Heat B — American mill
C 0.16 · Cr 15.4 · Ni 1.62
- EN 1.4057 ✓
- ASTM 431 ✓
- 431S29 ✗
- Z15CN16-02 ✓
- SUS 431 ✓
- 14Kh17N2 ✗
- 14Cr17Ni2 ✗
Fails three ways for two reasons. Nickel is 0.38 % under the British floor; chromium is 0.6 % under the GOST and GB floor. This is the heat plotted as the dashed line in Figure 1, and it is the most common real-world conflict we see — a US-melted bar offered against a UK drawing.
Heat C — GOST-route mill
C 0.14 · Cr 17.1 · Ni 2.30
- EN 1.4057 ✗
- ASTM 431 ✓
- 431S29 ✓
- Z15CN16-02 ✗
- SUS 431 ✓
- 14Kh17N2 ✓
- 14Cr17Ni2 ✓
The reverse case, and the one that surprises European buyers. Chromium at 17.1 % is fine for the GOST, GB and BS ranges that extend to 18 % — but it is above the EN 10088-3 ceiling of 17.0 %. A cleaner, more corrosion-resistant heat that a strict EN inspection will still write up as non-conforming.
The dual-certification trap
Suppliers routinely print two or three designations on one certificate — "1.4057 / AISI 431 / SUS 431". That is legitimate only when the reported analysis falls inside every band listed. Heat B above would carry a technically false dual certificate if 431S29 were added to that line. When you receive a multi-designation MTC, check the analysis against each designation named, not just the one you ordered to.
5. Delivery conditions don't map at all
Composition is the easy half. The harder half is that the seven systems describe heat treatment condition in fundamentally incompatible ways, and this is where most cross-border specification errors actually originate.
EN 10088-3 is the only one of the seven that puts the mechanical result inside the designation. When you write 1.4057+QT900 you have specified a tensile band, a proof stress minimum, an elongation minimum, an impact minimum and — critically — a limiting ruling section, all in nine characters. Nothing in the ASTM, JIS, GOST or GB systems does that.
| System | Soft / machining condition | Hardened and tempered | Property band in the designation? |
|---|---|---|---|
| EN 10088-3 | +A (annealed) | +QT800 · +QT900 | Yes — Rm, Rp0.2, A, KV and ruling section |
| ASTM A276 / A479 | Condition A | Condition T / H | Partly — minimums only, no upper bound |
| BS 970 Part 1 | Condition P (softened) | Condition letter, e.g. T, U | Yes — a tensile band per letter |
| NF A35-573 | Recuit (annealed) | Trempé-revenu, class stated | Partly |
| JIS G4303 | Annealed | Suffix H (quenched & tempered) | Minimums only |
| GOST 5632 | No suffix system | Regime written out in the order | No |
| GB/T 1220 | No suffix system | Regime written out in the order | No |
| Condition | Ruling section | Rp0.2 min | Rm | Elongation min | KV min |
|---|---|---|---|---|---|
| +A | — | — | — | — | ≤ 295 HB |
| +QT800 | ≤ 160 mm | 600 MPa | 800–950 MPa | 14 % | 25 J |
| +QT900 | ≤ 160 mm | 700 MPa | 900–1050 MPa | 12 % | 20 J |
Indicative values for longitudinal specimens; confirm against the edition of EN 10088-3 in force. The ruling-section limit is what governs heavy forgings — above roughly 160 mm the +QT designations no longer carry a guarantee and properties must be agreed separately.
The size clause nobody reads
Writing "1.4057+QT900" on a Ø 500 mm forging asks for something the standard does not promise. The QT bands are written against a limiting section because a martensitic steel simply cools more slowly at the core of a heavy piece. On large cross-sections the correct approach is to specify the property you need, the test location that must achieve it, and let the heat treatment be engineered backwards from there.
6. The near-misses: 1.4044, Z15CN17-03 and 17Cr16Ni2
Three designations circulate alongside the main seven and are frequently, and wrongly, treated as drop-in synonyms.
1.4044 and Z15CN17-03
You will see 1.4044 and Z15CN17-03 printed next to 1.4057 in supplier tables. They belong to the same family but sit at a higher nickel level — the French designation says so in its own name, "17-03" against "16-02". If a drawing calls for Z15CN17-03 and you are offered X17CrNi16-2, that is a substitution to be agreed in writing, not a translation.
GB/T 1220 lists two grades, not one
This is the single most useful thing to know when a Chinese certificate lands on a European desk. GB/T 1220 contains both 14Cr17Ni2 (the former 1Cr17Ni2, inherited from the Soviet standard) and 17Cr16Ni2, which was added specifically to align with the European grade.
| GB/T grade | C | Cr | Ni | Closest true match |
|---|---|---|---|---|
| 14Cr17Ni2 (ex 1Cr17Ni2) | 0.11–0.17 | 16.0–18.0 | 1.50–2.50 | GOST 14Kh17N2 |
| 17Cr16Ni2 | 0.12–0.22 | 15.0–17.0 | 1.50–2.50 | EN 1.4057 / X17CrNi16-2 |
Almost every English-language cross-reference table on the internet lists only 1Cr17Ni2 against 1.4057. It is the wrong one of the two.
The practical consequence: if you are buying to EN 10088-3 from a Chinese mill and the certificate says 14Cr17Ni2, the analysis may well be outside your carbon and chromium bands even though the grade is described as equivalent. Ask for 17Cr16Ni2, or better, order to 1.4057 directly and require the certificate to state it.
7. Which standard governs a forging, as opposed to a bar
A second layer of confusion sits on top of the grade designation: the product standard. EN 10088-3 defines the chemistry and the delivery conditions, but its scope is semi-finished products, bars, rods, wire, sections and bright products. It is not the governing standard for an open die forging.
- EN 10250-4 — open die steel forgings, stainless part. References EN 10088-3 chemistry, sets its own rules for sampling, test location, testing frequency and dimensional tolerance.
- EN 10222-5 — forgings for pressure purposes, martensitic and austenitic stainless. Applies when the part is a pressure-retaining component under PED.
- ASTM A473 — stainless steel forgings. The American counterpart to EN 10250-4.
- ASTM A276 / A479 — bar and shape. Frequently cited on forging certificates, which is technically incorrect.
A certificate that names only EN 10088-3 for a heavy forged shaft is not wrong about the steel, but it is silent about where the test specimen came from — and on a heavy forging, specimen location is the entire argument. We ask customers to state the product standard, the specimen orientation and the extraction position on the order, and we report them on our certificates when they are specified. You can see how that is handled across our full forging materials range.
8. What to write on the order
All of the above collapses into one habit: name one governing standard and make everything else subordinate to it. Cross-references belong in a note, never in the specification line. Here is a purchase-order block you can copy and adapt.
Grade
1.4057 (X17CrNi16-2) per EN 10088-3
Product standard
EN 10250-4, open die forging
Delivery condition
+QT900, or agreed equivalent where the ruling section exceeds 160 mm
Chemistry
Per EN 10088-3 only. Cross-references to AISI 431 / SUS 431 / 431S29 are informative and non-binding.
Test location
1/4 radius, longitudinal, mid-length
Impact
KV per EN ISO 148-1, 3 specimens, orientation stated on certificate
NDT
UT per EN 10228-3, quality class S3
Certificate
EN 10204 3.2, third-party inspector to be nominated
Adapt the condition, test location and NDT class to your application. The line that does the most work is the chemistry line — it removes any argument about which band applies.
Four questions that prevent most disputes
- Which single standard governs — and is it named on the drawing and the order?
- Is the product standard for a forging cited, not just the bar standard?
- Does the delivery condition have a ruling section limit, and is your part inside it?
- If the certificate lists multiple designations, does the reported analysis satisfy all of them?
9. Questions we get asked
Is AISI 431 the same as 1.4057 / X17CrNi16-2?
They are the same alloy family and are treated as equivalents in every cross-reference table, but the specified bands are not identical. EN 10088-3 sets carbon at 0.12–0.22 % with a 1.50 % nickel minimum; ASTM A276 sets carbon at 0.20 % maximum with no minimum and a 1.25 % nickel minimum. A heat can satisfy one and sit outside the other. State which standard governs on the purchase order.
Why does BS 431S29 specify more nickel than AISI 431?
BS 970 Part 1 requires 2.0–3.0 % nickel for 431S29, against 1.25–2.50 % in ASTM A276 and JIS G4303 and 1.50–2.50 % in EN 10088-3. The British band sits almost entirely above the American one. A heat at 1.60 % nickel meets six of the seven specifications in this article and fails 431S29 — see Heat B in section 4.
What is the difference between 14Cr17Ni2 and 17Cr16Ni2 in GB/T 1220?
14Cr17Ni2 is the former 1Cr17Ni2, derived from GOST 14Kh17N2, with carbon 0.11–0.17 % and chromium 16.0–18.0 %. 17Cr16Ni2 was added to align with the European grade and carries carbon 0.12–0.22 % with chromium 15.0–17.0 %. If a Chinese certificate is being accepted against an EN order, 17Cr16Ni2 is the correct match, not 1Cr17Ni2.
What do +QT800 and +QT900 mean?
They are EN 10088-3 delivery conditions that tie the designation directly to a guaranteed property band. +QT800 gives approximately 800–950 MPa tensile with 600 MPa minimum proof stress; +QT900 gives approximately 900–1050 MPa with 700 MPa minimum. Both are quoted against a limiting ruling section of around 160 mm. No other standard system in this article carries the property band inside the designation.
Can I accept a SUS 431 certificate against a 1.4057 order?
Usually yes, provided you check two things: that the reported carbon is at least 0.12 % — JIS sets no carbon minimum — and that nickel is at least 1.50 %, since JIS allows down to 1.25 %. If both are satisfied, the analysis is inside the EN band and the substitution is defensible. If either is below, it is a concession, not an equivalence.
Which standard should I specify if the project spans several countries?
Specify the standard of the jurisdiction where the equipment will be certified and operated, not where it is bought. For a plant in the EU, EN 10088-3 with the appropriate product standard and EN 10204 certification will satisfy notified bodies and PED requirements. Add other designations as informative notes only. If you are unsure, send us the drawing and the destination and we will be glad to look at it with you before you commit to an order.
Do these composition differences change how the steel actually behaves?
Marginally, and mostly at the extremes. A heat at the top of the EN carbon band will reach a higher as-quenched hardness and be slightly harder to weld than one at the GOST maximum. A heat at the top of the BS nickel band will have less residual delta-ferrite in heavy sections. For most applications the difference is within normal batch scatter — which is precisely why the paperwork problem outlives the engineering one.
Specifying this grade on a live project?
Send us the drawing and the governing standard. Our engineering team will confirm feasibility, propose the delivery condition and flag any cross-standard conflict before you place the order. We aim to reply within one business day.
Manufacturing capability, size range, heat treatment routes and inspection scope are set out in full on the main product page.
1.4057 / X17CrNi16-2 forged parts
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