When your application demands sustained performance above 500°C with zero tolerance for creep, standard stainless steels and low-alloy tool steels quickly reach their limits. 1.3980 — standardized under EN 10302:2008 as X5NiCrTiMoV26-15 — is one of the select group of alloys that genuinely delivers: combining a precipitation-hardened austenitic microstructure with carefully balanced Ni, Cr, Ti, Mo, and V additions to produce strength levels that remain firm at temperatures that would soften most competing grades.
This guide covers everything a procurement engineer, metallurgist, or project manager needs to know about 1.3980 steel — from its alloying logic to heat treatment schedules, forgeability windows, and the industrial sectors where it is specified globally. Where relevant, we draw on 25+ years of open die forging and seamless ring rolling experience at Jiangsu Liangyi Co., Limited in Jiangyin, Jiangsu Province, China.
1. What Is 1.3980 Steel — And Why Does It Exist?
The designation 1.3980 is a European material number. Its full name, X5NiCrTiMoV26-15, is a compressed specification in DIN/EN coding language:
X = stainless (Cr ≥ 10.5%) · 5 = 0.05% C · Ni26 ≈ 26% nickel · Cr15 ≈ 15% chromium · Ti = titanium added · Mo = molybdenum added · V = vanadium added
The alloy belongs to the precipitation-hardening (PH) austenitic heat-resistant steel family. It was engineered to fill a critical performance gap: conventional austenitic grades like 304, 316, and 321 provide excellent corrosion resistance but lose strength rapidly above 500°C. High-speed tool steels offer hardness but suffer from poor oxidation resistance and brittle behavior at elevated temperature. 1.3980 bridges both requirements at the boundary where iron-based alloys reach their practical limit.
The "650°C ceiling" and where 1.3980 fits
In power generation turbines, compressors, and oil refinery reactors, engineers routinely encounter the "650°C ceiling" — the upper service temperature at which most iron-base alloys become uneconomical. Above it, nickel superalloys take over, but at dramatically higher cost. 1.3980 sits at the apex of iron-base PH steel performance, maximizing strength-per-dollar right at that boundary.
2. Chemical Composition of 1.3980 (X5NiCrTiMoV26-15)
The following limits are defined in EN 10302:2008. All values are weight percentages.
| Element | Min (%) | Max (%) | Typical (%) | Role in the alloy |
|---|---|---|---|---|
| C (Carbon) | 0.03 | 0.08 | 0.05 | Low C preserves toughness; prevents grain-boundary carbides |
| Si (Silicon) | — | 0.70 | 0.40 | Deoxidizer; minor oxidation resistance benefit |
| Mn (Manganese) | — | 1.00 | 0.60 | Austenite stabilizer; minor solid-solution strengthener |
| P (Phosphorus) | — | 0.030 | <0.020 | Residual; kept low to avoid temper embrittlement |
| S (Sulfur) | — | 0.015 | <0.010 | Residual; low for toughness and fatigue resistance |
| Ni (Nickel) | 24.0 | 27.0 | 26.0 | Austenite former; lowers stacking fault energy; drives γ′ precipitation |
| Cr (Chromium) | 13.5 | 16.0 | 15.0 | Oxidation/corrosion resistance; solid-solution strengthening |
| Mo (Molybdenum) | 1.0 | 1.5 | 1.25 | Solid-solution strengthening; creep resistance; pitting resistance |
| Ti (Titanium) | 1.9 | 2.3 | 2.1 | Primary γ′ [Ni₃Ti] precipitate former — key to precipitation hardening |
| V (Vanadium) | 0.10 | 0.50 | 0.25 | Refines grain size; secondary carbide/nitride precipitation hardening |
| Al (Aluminum) | — | 0.35 | 0.15 | Co-precipitate with Ti in γ′ phase; deoxidizer |
| B (Boron) | — | 0.010 | 0.003 | Segregates to grain boundaries; improves creep rupture life |
| Fe (Iron) | Balance | Austenitic matrix base | ||
The Ti/(C+N) ratio must be held above 4:1. This ensures all carbon and nitrogen are scavenged into stable TiC and TiN particles, leaving the matrix free for clean Ni₃Ti (γ′) precipitation — the primary mechanism behind this alloy's high-temperature strength. Deviation from this ratio produces inconsistent aging response and inferior creep properties.
3. Mechanical Properties of 1.3980 Forgings
Properties are strongly dependent on heat treatment condition. After full solution annealing and precipitation hardening, tensile strength can exceed 1,100 MPa while maintaining meaningful impact toughness at room temperature.
High-temperature property retention
The γ′ precipitates (Ni₃Ti / Ni₃Al intermetallics) remain stable up to approximately 700°C before significant over-aging dissolves them. This gives 1.3980 a much flatter strength-temperature curve than competing iron-base grades in the critical 500–650°C window.
| Temperature | Rm (MPa, typical) | Rp0.2 (MPa, typical) | Creep strength — 10⁵ h (MPa) |
|---|---|---|---|
| 20°C (RT) | 1,050 | 700 | — |
| 300°C | 960 | 660 | — |
| 500°C | 870 | 610 | 360 |
| 550°C | 820 | 580 | 280 |
| 600°C | 760 | 540 | 190 |
| 650°C | 680 | 490 | 105 |
4. Heat Treatment: Solution Annealing and Precipitation Hardening
Both the solution annealing temperature and aging temperature must be tightly controlled — deviations of ±15°C from target can result in understrength parts or excessive residual stress. The full cycle consists of four stages:
Solution Annealing — 950°C to 1000°C / Air or Water Quench
All precipitates are dissolved into the austenitic matrix (hold time: 1–4 hours depending on section thickness). Rapid cooling retains the supersaturated solid solution. Hardness at this stage is low (~28–32 HRC equivalent), giving good machinability for pre-machining operations.
Intermediate Stabilization (Optional) — 840°C / 4h / Air Cool
For heavy cross-sections (>300 mm) or components requiring maximum stress-rupture life, this intermediate step promotes uniform titanium carbonitride distribution before precipitation hardening, preventing coarse precipitate bands that would compromise fatigue resistance.
Precipitation Hardening (Aging) — 720°C ± 10°C / 8–16h / Air Cool
The critical step. Fine Ni₃Ti γ′ precipitates nucleate coherently within austenite grains. An 8-hour minimum gives peak precipitate density; 16 hours provides slightly higher creep resistance at minor cost to room-temperature ductility. Heating rate must not exceed 8°C/minute for heavy forgings.
Property Verification and Inspection
Heat treatment is verified through hardness testing (30–36 HRC target), tensile and proof stress coupon testing, and Charpy impact testing per EN 10302. Jiangsu Liangyi maintains full traceability from heat number through every furnace time-temperature cycle.
5. Forging Behavior and Processing
Despite its high alloy content, 1.3980 is workable when processed within its correct hot-working window. The austenitic structure provides good ductility at forging temperature, but the narrow window and the risk of gamma prime dissolution require tight furnace discipline.
Hot-working temperature range
The recommended open die forging temperature for 1.3980 is 1,000°C to 1,180°C. Below 950°C, insufficient ductility risks cracking. Above 1,220°C, incipient melting at grain boundaries causes irreversible damage. For precision parts, we target a finishing temperature above 1,020°C to ensure full recrystallization.
Seamless ring rolling
1.3980 rings can be seamlessly rolled to diameters up to 6,000 mm. The primary challenge is controlling post-rolling cooling rate to avoid residual stress cracking — water spray cooling is avoided; controlled forced-air cooling is preferred. At Jiangsu Liangyi, rolled rings are transferred directly into pre-heated holding furnaces after rolling to equalize temperature before the solution annealing cycle begins.
Available forged shapes
1.3980 can be produced in all standard open die forging and seamless ring rolling geometries — from round bars and discs through to large-diameter seamless rings, hollow bars, and complex near-net shapes. The forging process imparts a refined directional grain structure that improves fatigue resistance and tensile properties compared to cast or machined-from-bar alternatives, which is why most turbine disc and retaining ring specifications explicitly require forged material rather than cast or wrought billet.
For detailed size tables, available dimensional ranges, and surface finish options for each shape, visit our 1.3980 forging parts page, which also includes a direct quote request form.
6. Industrial Applications of 1.3980 Forgings
The combination of high-temperature strength, creep resistance, low magnetic permeability, and oxidation resistance at up to 650°C makes 1.3980 the material of choice across several demanding industries.
| Industry | Typical Components | Why 1.3980 Is Specified |
|---|---|---|
| Power Generation | Turbine discs, blisks, retaining rings, labyrinth seals | Holds strength above 600°C; creep life matches turbine overhaul intervals (100,000h+) |
| Oil & Gas | Valve bodies, bonnet flanges, pump impellers, compressor impellers | High-temperature strength combined with low magnetic permeability for subsea sensing applications |
| Nuclear Power | Reactor coolant pump parts, primary circuit valve internals, pump shafts | Non-magnetic behavior essential in high-flux environments; exceptional reliability under long-term thermal cycling |
| Petrochemical / Refining | Reformer fittings, cracker valve components, high-temperature flanges | Resists carburization and oxidation in hydrocarbon process streams at 550–650°C |
| Aerospace & Defense | Engine disc forgings, actuator housings, generator retaining rings | Superior strength-to-weight at elevated temperature vs. standard austenitic grades |
For verified specifications, full dimensional capability tables, compliance documentation, and to request a quote, see our dedicated custom X5NiCrTiMoV26-15 forged components page.
7. How Does 1.3980 Compare to Similar Alloys?
| Property | 1.3980 / X5NiCrTiMoV26-15 | A-286 / GH2132 | Inconel 718 | 17-4PH |
|---|---|---|---|---|
| Steel family | PH Austenitic | PH Austenitic | Ni Superalloy | Martensitic PH |
| Max service temp | 650°C | 650°C | ~720°C | ~350°C |
| Tensile strength (RT) | 930–1180 MPa | 900–1100 MPa | 1240–1380 MPa | 900–1310 MPa |
| Magnetic permeability | ≤ 1.02 (non-magnetic) | ≤ 1.02 | ≤ 1.01 | Magnetic |
| Creep resistance at 650°C | Excellent | Very Good | Excellent | Poor |
| Weldability | Good (PWHT required) | Good | Moderate | Good |
| Relative material cost | Moderate | Moderate | High | Low–Moderate |
When A-286 and 1.3980 are placed side by side in demanding power generation applications, 1.3980's vanadium-refined microstructure and boron grain-boundary strengthening can deliver meaningfully longer creep rupture life at 600–650°C — a margin that directly extends turbine overhaul intervals and reduces lifecycle costs.
8. Weldability and Machinability
Weldability
1.3980 can be welded by TIG (GTAW) and MIG (GMAW) processes using matching filler metals or Ni-base consumables (ERNiCrMo-3 type) for dissimilar joints. Pre-heat is generally not required at room temperature, but post-weld heat treatment (PWHT) is mandatory for structural welds: the heat-affected zone must be re-solution-annealed and re-aged to restore precipitate distribution and recover tensile properties. Skipping PWHT leaves a soft, over-aged HAZ that will become the weakest point under creep loading.
Machinability
In the solution-annealed (soft) condition, 1.3980 machines comparably to 316 stainless steel — demanding but workable with carbide tooling, rigid setups, and positive-rake geometry. Work hardening rate is moderate. After precipitation hardening (30–36 HRC), machining becomes significantly more challenging; all critical features should be roughed out in the annealed condition and only finish-machined after the aging cycle. Generous coolant flow is essential to prevent local over-aging of the surface layer.
9. Quality Control and Certification
Given the safety-critical nature of 1.3980 components — turbine discs, nuclear pump shafts, pressure-retaining valves — quality documentation and traceability are non-negotiable. When sourcing 1.3980 forgings, require:
- MTC 3.1 or 3.2 Certificate per EN 10204 — with heat number, chemical composition, and mechanical test results traceable to the specific forging batch
- Chemical composition report from a certified laboratory, meeting EN 10302:2008 requirements as a minimum
- Mechanical test report — tensile (Rm, Rp0.2, A%), Charpy impact (KV), and hardness
- Ultrasonic testing (UT) report per EN 10228-3 or customer-specified acceptance level
- Magnetic particle or liquid penetrant (MT/PT) testing on final machined surfaces for surface defect detection
- Heat treatment records — full time-temperature trace charts from calibrated, certified furnaces
- Dimensional inspection report — CMM or conventional measurement per customer drawing
At Jiangsu Liangyi, our QC chain supports all the above, with third-party inspection available upon customer request through internationally recognized inspection agencies. We hold ISO 9001:2015 certification covering the complete production scope from steel melting through final machining and testing.