Grade Identity & Designations
X2CrNiMoN18-14-3 (EN material number 1.3952) is a non-magnetizable austenitic stainless steel. It has no exact ASTM equivalent but is closest in composition to a high-nickel, nitrogen-controlled 316-family grade. In European engineering documentation, "1.3952" and "X2CrNiMoN18-14-3" refer to the same material.
Engineers encounter this material under several names depending on which standard document they reference. The EN 10088-1 designation X2CrNiMoN18-14-3 is internationally recognised, while the material number 1.3952 appears on mill test certificates and procurement documents across Europe. The "1.39xx" number block — distinct from the common "1.44xx" austenitic stainless family — signals non-magnetizable character, which is the defining commercial reason this grade exists.
The ASTM system has no exact numerical equivalent. Buyers sourcing for projects requiring European and ASTM compliance should note that ASTM A182 Grade F48 covers a similar but not identical chemical window — dual certification requires careful ingot chemistry selection to satisfy both composition windows simultaneously.
| Designation System | Identifier | Standard Reference | Primary Use Context |
|---|---|---|---|
| EN Material Name | X2CrNiMoN18-14-3 | EN 10088-1/-3, EN 10250-4 | European engineering specifications |
| EN Material Number | 1.3952 | EN 10088-1 | Mill certificates, procurement documents |
| Common Trade Name | Non-Mag 316LN / Non-Mag 18-14-3 | Trade use | RFQs, internal specifications |
| Closest ASTM Grade | A182 Grade F48 (similar chemistry) | ASTM A182 | US / North American projects |
| Steel Family | Austenitic — non-magnetizable (1.39xx series) | EN 10088-1 | MRI, defence, subsea electronics |
X2 = max 0.03% carbon (ultra-low carbon, anti-sensitization). Cr18 = 17–20% chromium nominal. Ni14 = 13.5–17.5% nickel (elevated for zero ferrite). Mo3 = ~3% molybdenum. N = deliberate nitrogen addition (0.10–0.20%). The "18-14-3" suffix reflects nominal Cr-Ni-Mo composition targets.
Why X2CrNiMoN18-14-3 Is Non-Magnetic: The Metallurgical Mechanism
The defining characteristic placing 1.3952 in the rare "non-magnetizable" category is its fully austenitic microstructure with zero delta ferrite. Standard 304 or 316L stainless steels contain residual delta ferrite and can develop strain-induced martensite during cold working — both phases are ferromagnetic and raise the relative magnetic permeability (μr) above the 1.01 threshold critical for electromagnetically sensitive environments.
X2CrNiMoN18-14-3 achieves μr ≤ 1.005 through three simultaneous alloying strategies: (1) nickel is elevated to 13.5–17.5% — far above standard 316L (10–14%) — pushing the Ni-equivalent deep into the fully austenitic phase field on the Schaeffler diagram; (2) nitrogen (0.10–0.20%) functions as a potent austenite stabiliser with a coefficient approximately 25× that of nickel per unit weight, eliminating residual ferrite without additional nickel cost; (3) ultra-low carbon (≤ 0.03%) prevents carbide precipitation that could locally destabilise the austenite phase.
Even 1.3952 can develop slightly elevated permeability after heavy cold deformation (>30% reduction), as strain energy partially transforms austenite to martensite. Components for MRI or magnetic detector environments must be specified in solution-annealed (SA) condition and must not undergo cold straightening or cold sizing after final heat treatment. Always re-anneal and re-quench after any significant cold deformation.
X2CrNiMoN18-14-3 Chemical Composition: Every Element Explained
| Element | EN 10088-3 Limit (wt%) | Typical Forging Heat | Primary Metallurgical Function |
|---|---|---|---|
| C — Carbon | ≤ 0.030% | 0.015–0.025% | Ultra-low C prevents sensitization; the "X2" prefix in the grade name denotes this limit |
| Si — Silicon | ≤ 1.00% | 0.30–0.65% | Deoxidiser during steelmaking; excessive Si promotes sigma phase at elevated temperature |
| Mn — Manganese | ≤ 2.00% | 1.40–1.80% | Austenite stabiliser; MnS inclusion morphology control; secondary nitrogen solubility improver |
| P — Phosphorus | ≤ 0.045% | ≤ 0.025% | Controlled for hot-workability; high P causes hot-cracking in heavy forgings |
| S — Sulfur | ≤ 0.015% | ≤ 0.005% | Low S reduces MnS inclusion density — critical initiation sites for pitting corrosion |
| Cr — Chromium | 17.0–20.0% | 18.0–19.0% | Primary passive film former; PREN contributor at 1× weight factor |
| Ni — Nickel | 13.5–17.5% | 15.0–16.5% | Full austenite stabilisation; zero delta ferrite; non-magnetic guarantee; SCC resistance |
| Mo — Molybdenum | 2.50–3.50% | 2.80–3.30% | Passive film stabiliser in Cl⁻ environments; PREN contributor at 3.3× weight factor |
| N — Nitrogen | 0.10–0.20% | 0.13–0.18% | Austenite stabiliser (25× Ni factor); solid-solution strengthener; PREN at 16× factor |
Why Nitrogen Is the Engineering Keystone of 1.3952
Nitrogen simultaneously fulfils four engineering objectives in X2CrNiMoN18-14-3, each of which would otherwise require a separate alloying addition:
- Austenite stabilisation — nitrogen stabilises the austenite phase at a coefficient approximately 25× that of nickel per unit weight, eliminating delta ferrite and ensuring μr ≤ 1.005.
- Solid-solution strengthening — approximately 8–10 MPa yield strength increase per 0.01% N addition. This enables the 200 MPa minimum yield strength requirement to be met at ultra-low carbon content.
- PREN contribution — nitrogen carries the highest weighting factor (16×) of any element in the standard PREN formula, adding 1.6–3.2 PREN points across the 0.10–0.20% specification window.
- Sensitization suppression — nitrogen competes with carbon at grain boundaries, reducing carbide precipitation risk and helping maintain full corrosion resistance after thermal processing.
Nitrogen is volatile above ~1,500°C and evaporates from molten steel during conventional ESR remelting. For critical-service 1.3952 forgings, specify PESR (Protective Atmosphere ESR) melting — the chamber is held under nitrogen-argon mixed atmosphere to prevent N loss and ensure specification compliance from ingot top to bottom. Demand 3-point ingot chemistry verification, not a single ladle sample.
PREN Calculation for X2CrNiMoN18-14-3 and What the Number Means
The PREN of X2CrNiMoN18-14-3 is typically 28–36. Using the formula PREN = %Cr + 3.3×%Mo + 16×%N with typical chemistry (Cr 18.5%, Mo 3.0%, N 0.15%): PREN = 18.5 + 9.9 + 2.4 = 30.8. This is higher than 316L (≈25) but below super-austenitic 254 SMO (≈44).
X2CrNiMoN18-14-3 typical: Cr 18.5%, Mo 3.0%, N 0.15%
= 18.5 + (3.3 × 3.0) + (16 × 0.15)
= 18.5 + 9.9 + 2.4 = 30.8
PREN Benchmarks: 1.3952 vs. Competing Engineering Grades
X2CrNiMoN18-14-3 is not chosen for maximum pitting resistance — grades like 254 SMO and Duplex 2507 outperform it. It is chosen when non-magnetic character (μr ≤ 1.005) is a hard design requirement that eliminates all duplex, martensitic, and standard austenitic alternatives. The corrosion advantage over 316L (PREN +5 to +11 points) is a beneficial secondary property. Applications in MRI equipment, naval vessels, and scientific instruments specify this grade precisely because no magnetic alternative can serve the application.
Mechanical & Physical Properties of X2CrNiMoN18-14-3 (1.3952)
Solution-annealed 1.3952 forgings: UTS ≥ 500 MPa (typically 540–620 MPa), YS ≥ 200 MPa (typically 230–280 MPa), Elongation ≥ 40%, Hardness max 215 HB (typically 150–185 HB). Magnetic permeability μr ≤ 1.005. No ductile-to-brittle transition — toughness retained to −196°C.
Mechanical Properties — Solution-Annealed Condition (EN 10250-4)
| Property | EN 10250-4 Minimum | Typical Forging Achieved | Test Standard |
|---|---|---|---|
| Ultimate Tensile Strength (UTS) | ≥ 500 MPa | 540–620 MPa | EN ISO 6892-1 / ASTM A370 |
| 0.2% Proof Yield Strength (YS) | ≥ 200 MPa | 230–280 MPa | EN ISO 6892-1 |
| Elongation at Break (A₅₀) | ≥ 40% | 48–56% | EN ISO 6892-1 |
| Reduction of Area | ≥ 50% | 58–68% | EN ISO 6892-1 |
| Brinell Hardness (HB) | Max 215 HB | 150–185 HB | EN ISO 6506-1 |
| Charpy Impact at +20°C | Not specified | > 200 J (full-size) | EN ISO 148-1 / ASTM E23 |
| Charpy Impact at −196°C | Not specified | 100–150 J (no DBTT) | EN ISO 148-1 |
| ASTM Grain Size | Not specified | ASTM No. 5–8 | ASTM E112 |
Physical Properties — Reference Values at 20°C
| Property | Value | Engineering Design Note |
|---|---|---|
| Density | ≈ 7.99 g/cm³ | Near-identical to 316L; no adjustment in weight calculations |
| Elastic Modulus | ≈ 195 GPa | Decreases to ~180 GPa at 200°C; apply temperature correction for elevated-service design |
| Magnetic Permeability (μr) | ≤ 1.005 | Paramagnetic — certified for MRI, MEMS, naval non-magnetic applications |
| Thermal Conductivity | ≈ 12.5 W/(m·K) at 100°C | Low vs carbon steel (~50 W/(m·K)); relevant for heat exchanger thermal design |
| Thermal Expansion Coefficient | ≈ 16.0 × 10⁻⁶ /°C | Compatible with 316L tubes; no differential expansion mismatch in tube-sheet equipment |
| Max Continuous Service Temp. | 450°C | Sigma phase precipitation risk above 450°C; avoid slow cooling through 600–900°C range |
Because 1.3952 is fully austenitic with zero ferrite, it retains excellent toughness down to −196°C (liquid nitrogen temperature). Typical full-size Charpy impact energy exceeds 100 J at −196°C. This makes it suitable for cryogenic vessel closures, superconducting magnet support structures, and MRI cryostat fittings where impact resistance at low temperature is a design requirement alongside non-magnetic character.
Heat Treatment Protocol for X2CrNiMoN18-14-3 Forgings
Solution annealing is the sole standard heat treatment for 1.3952. Unlike carbon steels where heat treatment develops hardness, solution annealing for X2CrNiMoN18-14-3 restores full corrosion resistance and homogenises the microstructure after forging deformation. No tempering is required or permitted.
Prolonged exposure of 1.3952 within 600–900°C — during welding heat cycles, post-weld treatment, or accidental slow cooling — promotes sigma phase (σ-Fe-Cr-Mo intermetallic) precipitation. Sigma phase simultaneously reduces toughness and pitting corrosion resistance. Detection method: Charpy impact testing at −40°C reveals sigma phase embrittlement before it causes field failure. All fabrication sequences must avoid slow cooling through this temperature range.
Welding X2CrNiMoN18-14-3: Filler Selection & Process Rules
X2CrNiMoN18-14-3 is weldable by standard austenitic processes, but three aspects require more careful control than for 316L: nitrogen loss in the weld pool, hot-cracking sensitivity in zero-ferrite weld metal, and HAZ sensitization avoidance.
Recommended Filler Metals by Process
| Process | Recommended Filler | EN Standard | Target FN | Critical Note |
|---|---|---|---|---|
| GTAW — TIG | ER316LN / ER385 | W 19 13 4 LN | < 3 FN | Use Ar + 2–5% N₂ shielding gas to compensate weld pool nitrogen evaporation |
| GMAW — MIG | ER316LN | G 19 13 4 LN | < 3 FN | Elevated travel speed reduces heat input and nitrogen burn-off rate |
| SMAW — MMA | E316LN-16 / E385-16 | E 19 13 4 LN R | < 3 FN | Low-hydrogen electrodes; preheat is NOT required and is counterproductive |
| SAW | S 19 13 4 LN | EN ISO 14343-A | < 3 FN | Basic flux preferred; reduces weld metal inclusion content and hot-cracking susceptibility |
Six Critical Welding Process Rules
- No preheat — it is harmful, not helpful. Preheating increases time spent in the sensitization range (600–850°C), worsening HAZ corrosion resistance rather than preventing cracking.
- Interpass temperature maximum: 150°C. Lower than typical austenitic steels due to zero-ferrite microstructure's heightened solidification cracking susceptibility. Verify with contact thermometer between each pass.
- Heat input: 0.5–1.5 kJ/mm recommended. Higher heat input increases nitrogen burn-off and sensitization range exposure time. Use stringer beads, not weave technique.
- N₂ back-purge for GTAW root pass. Use Ar + 5% N₂ for root runs to prevent nitrogen depletion and porosity on the weld root face.
- Post-weld solution anneal strongly recommended for corrosion-critical joints. Water quench from 1,050°C re-dissolves any HAZ carbides formed during multi-pass welding.
- Pickling + passivation required on all weld areas. Mechanical grinding alone does not restore passivation on austenitic weld metal in corrosion service.
X2CrNiMoN18-14-3 vs 316L, 904L, Duplex 2205 & 254 SMO
| Property | 316L (1.4404) | 1.3952 ★ X2CrNiMoN18-14-3 | 904L (1.4539) | Duplex 2205 | 254 SMO |
|---|---|---|---|---|---|
| PREN (Typical) | 24–27 | 28–36 | 34–36 | 34–38 | 42–46 |
| Magnetic μr | 1.01–2.0* | ≤ 1.005 | ≤ 1.005 | 1.5–3.0 | ≤ 1.005 |
| Min Yield Strength | 170 MPa | 200 MPa | 220 MPa | 450 MPa | 300 MPa |
| Cryogenic Toughness | Good | Excellent | Excellent | DBTT <−50°C | Excellent |
| NACE MR0175 Material Eligible | Yes | Yes (≤235 HB) | Yes | Yes | Yes |
| Relative Forging Cost | 1.0× baseline | 1.6–2.0× | 2.5–3.0× | 1.4–1.7× | 3.5–5.0× |
| Best Fit Application | General Cl⁻ service | Non-magnetic + moderate Cl⁻ | Reducing acids (H₂SO₄) | High strength + Cl⁻ | Seawater / severe pitting |
★ = X2CrNiMoN18-14-3 (1.3952) | *316L can develop μr up to 3.0 after cold work; 1.3952 maintains μr ≤ 1.005 in all standard conditions including after machining and threading.
Standard 316L appears to pass magnetic testing after solution annealing (μr ≈ 1.01–1.05), but after any cold forming, straightening, threading, or machining operations its permeability rises significantly — often to μr 1.2–3.0. For applications requiring μr ≤ 1.01 throughout the component's entire service life, only grades in the 1.39xx non-magnetizable family guarantee this across all manufacturing operations and in-service conditions.
Industrial Applications of X2CrNiMoN18-14-3 Forged Parts
In the following application categories, the non-magnetic requirement is a hard safety or functional constraint that eliminates all magnetic alloys regardless of cost or corrosion performance. 1.3952 is specified not primarily for corrosion resistance, but because it is the only metallic structural alloy that simultaneously provides non-magnetic character and adequate structural properties.
Medical Imaging — MRI Equipment Structures
Structural support frames, patient table systems, magnet bore fixtures and cryostat fittings in MRI machines operate in static magnetic fields up to 3 Tesla. Any ferromagnetic component creates imaging artefacts, force-attraction safety hazards and quench risks. 1.3952 is a primary specification material for non-magnetic structural forgings in MRI environments, from bore support rings to patient positioning hardware.
Naval — Mine Countermeasure Vessels
Mine countermeasure vessels (MCMVs) and submarines require non-magnetic hull fittings, shaft seals, propulsion components and through-hull connectors to minimise vessel magnetic signature. 1.3952 meets general non-magnetic material requirements for naval applications (μr ≤ 1.005 confirmed by Feritscope). Always verify compliance against your project-specific naval specification.
Scientific Research — Accelerators & NMR
Particle accelerator vacuum chamber flanges, NMR spectrometer structural elements, electron beam system housings and MEMS fabrication equipment require non-magnetic metallic structures to prevent field distortion. 1.3952 forged rings and flanges provide the structural integrity, vacuum-compatible surface quality and dimensional stability needed for precision scientific instruments.
Power Generation — Electromagnetic Bearing Rings
Active magnetic bearing housings and thrust bearing rings in advanced gas and steam turbine designs require non-magnetic metallic materials to prevent interaction with the electromagnetic control field sensors. Forged 1.3952 rings provide the dimensional stability, circularity tolerance and surface finish required for precision bearing fits in high-speed rotating machinery.
Oil & Gas — Subsea Sensor Housings
Subsea control module housings, acoustic positioning transponder bodies and electromagnetic flowmeter pressure-containing bodies must not distort sensor fields while resisting seawater corrosion in cathodically protected environments. 1.3952 forged housings serve both requirements simultaneously — non-magnetic character and PREN ≈ 30–32 for subsea chloride environments.
Defence — EOD & Anomaly Detection
Explosive ordnance disposal (EOD) tool housings, magnetic anomaly detection (MAD) equipment frames and degaussing system structural rings require non-magnetic metallic housings that will not compromise adjacent magnetic sensor sensitivity. 1.3952 provides structural load capacity without measurable magnetic signature contribution.
For dimensional specifications, material certification options and custom quotation, visit Jiangsu Liangyi's 1.3952 non-magnetic stainless steel forged parts page — covering seamless rolled rings up to OD 6,000 mm, open die bars, hollow forgings and EN 10204 3.1/3.2 documentation.
Why Forging Unlocks X2CrNiMoN18-14-3's Full Performance
For X2CrNiMoN18-14-3, the manufacturing route is not merely a shaping decision — it determines whether the finished component achieves the grade's theoretical properties in service. Forging provides two advantages specific to 1.3952 that no other route can replicate: refined grain structure and preserved non-magnetic character throughout the full cross-section.
Manufacturing Route Comparison
| Route | Internal Soundness | Grain Size (ASTM) | Fatigue Life vs Cast | μr After Processing |
|---|---|---|---|---|
| Sand / Investment Casting | Poorest — porosity, shrinkage | > ASTM 2 (coarse) | 1.0× baseline | Variable — casting defects can trap ferrite |
| Hot-Rolled Mill Bar | Moderate | ASTM 3–5 | 1.3–1.5× | ≤ 1.01 if SA; rises with machining |
| Open Die Forging | Excellent — fully consolidated | ASTM 5–8 | 1.8–2.5× | ≤ 1.005 throughout if SA (no cold work) |
| Seamless Ring Rolling | Excellent — continuous grain flow | ASTM 6–8 | 2.0–3.0× | ≤ 1.005 throughout if SA (no cold work) |
The Non-Magnetic Preservation Advantage of Forging
Cold-drawn bar stock undergoes significant cold work during the drawing process, which raises μr to 1.02–1.05 in surface layers even on 1.3952 grade. A solution-annealed forged ring or bar — processed exclusively through controlled hot-working followed by solution anneal and water quench, with no subsequent cold deformation — maintains certified μr ≤ 1.005 uniformly throughout the entire cross-section.
This matters for MRI structural frames and subsea sensor housings where even localised magnetic anomalies within a component — below bulk μr measurement threshold — can cause field distortion in proximity to high-resolution sensors. Specifying solution-annealed 1.3952 forgings from a manufacturer who hot-works exclusively and does not cold-draw eliminates this risk category entirely.
Jiangsu Liangyi manufactures custom 1.3952 forgings: 30 kg to 30,000 kg per piece. Seamless rolled rings OD 200–6,000 mm. Open die bars OD up to 800 mm × 8,000 mm length. Hollow forgings, discs and custom profiles. PESR ingot melting available on request. EN 10204 3.1/3.2 MTC. Feritscope μr ≤ 1.005 certification on request. ISO 9001:2015. Third-party inspection by SGS / BV / TÜV / Lloyd's Register. Standard lead time 15–30 working days. For full dimensional specifications and a custom quotation, see the 1.3952 X2CrNiMoN18-14-3 product page.
Frequently Asked Questions on X2CrNiMoN18-14-3
What is X2CrNiMoN18-14-3 steel and what is it used for?
X2CrNiMoN18-14-3 (material number 1.3952) is a non-magnetizable austenitic stainless steel standardised under EN 10088-1 and EN 10250-4. It achieves magnetic permeability μr ≤ 1.005 through elevated nickel (13.5–17.5%) and controlled nitrogen (0.10–0.20%), resulting in zero delta ferrite. Primary uses include MRI equipment structural components, naval mine countermeasure vessel fittings, scientific instrumentation housings, subsea sensor enclosures, and defence equipment requiring zero magnetic signature. PREN 28–36 provides meaningful corrosion resistance improvement over standard 316L.
Can 1.3952 X2CrNiMoN18-14-3 be used in NACE MR0175 sour service?
Yes. X2CrNiMoN18-14-3 is listed in NACE MR0175/ISO 15156-3 Table A.3 as a qualified austenitic alloy for H₂S sour service in the solution-annealed condition, provided hardness does not exceed 22 HRC (≈220 HV10 / 235 HB). Standard solution-annealed 1.3952 forgings typically achieve 150–185 HB — well within this limit. For demanding NACE service combining high Cl⁻ with H₂S, the higher-molybdenum ASTM A182 F48 (PREN 38–42) is generally preferred for additional margin.
What NDT methods are applicable to 1.3952 forgings?
Because X2CrNiMoN18-14-3 is fully non-magnetic, magnetic particle testing (MT) cannot be used — the material will not support a magnetic flux. Applicable methods are: Ultrasonic Testing (UT) per EN 10228-3 or ASTM A388 for volumetric inspection; Liquid Penetrant Testing (PT) per EN 10228-2 or ASTM E165 for surface indications; Radiographic Testing (RT) for complex geometries; and eddy current for surface layer inspection calibrated to the material's electrical resistivity. Specifying MT on 1.3952 in a purchase order is a common engineering error that should be corrected before production commences.
Is X2CrNiMoN18-14-3 the same as 316LN stainless steel?
No. Both are austenitic steels with controlled nitrogen, but 1.3952 has significantly higher nickel (13.5–17.5% vs 10–14% for 316LN / 1.4406) to ensure zero delta ferrite and guaranteed non-magnetic character. 1.3952 belongs to the non-magnetizable 1.39xx material number series — not the standard austenitic 1.44xx family. Standard 316LN can develop ferrite and martensite after cold work, raising μr above 1.01. 1.3952 maintains μr ≤ 1.005 through all standard manufacturing and service conditions.
What maximum ring and bar sizes are available in 1.3952?
Jiangsu Liangyi manufactures X2CrNiMoN18-14-3 forgings in the following ranges: Seamless rolled rings — OD 200 mm to 6,000 mm, wall thickness ≥ 20 mm, height 20–1,500 mm; Open die round bars — OD 20–800 mm, length up to 8,000 mm; Hollow forgings — OD 100–1,500 mm, bore 50–1,200 mm; Discs and blocks — OD/width up to 3,000 mm; Custom shapes per 2D/3D drawing — maximum single piece weight 30,000 kg. Minimum order: 1 piece. For rings above OD 3,000 mm, contact our engineering team for capacity confirmation.
Do you provide magnetic permeability (μr) certification for 1.3952 forgings?
Yes. On request, Jiangsu Liangyi provides Feritscope measurement reports per DIN EN ISO 8249 confirming delta ferrite content = 0 FN and magnetic permeability measurement confirming μr ≤ 1.005 in the solution-annealed condition. This documentation is included in the EN 10204 3.1 or 3.2 MTC package as an additional test report. Buyers for MRI equipment or defence non-magnetic applications should request this certification explicitly in their purchase specification and confirm measurement point coverage (surface, ½-radius, and core for critical applications).