X12CrNiWTiB16-13, 1.4962, NB 00144 St17-13W
Complete technical guide to premium martensitic stainless steels including 1.4938 (X12CrNiMoV12-3) - chemical composition, mechanical properties, heat treatment, creep performance, and applications in turbines and aerospace.
Table of Contents
What is X12CrNiWTiB16-13, 1.4962, NB 00144 St17-13W?
1.4938/X12CrNiMoV12-3 represents a premium martensitic stainless steel specifically developed for critical high-temperature applications in turbines and aerospace. Its balanced composition provides an excellent combination of strength, creep resistance, and corrosion resistance at temperatures up to 600°C. The strict quality control requirements across OEM specifications ensure reliable performance in demanding applications.
Austenitic stainless steels for turbine applications offer exceptional high-temperature strength, creep resistance, and corrosion resistance in demanding environments. This guide provides a comprehensive technical analysis of three important grades: 1.4962 (X12CrNiWTiB16-13), St17-13W (GE specification), and their equivalents.
Applications
X12CrNiWTiB16-13 / 1.4962 Applications
- Classification: Austenitic stainless steel with titanium and boron stabilization
- Applications: Gas turbine blades, combustion components, high-temperature fasteners
- Key Features:
- Excellent creep resistance at temperatures up to 750°C
- Good oxidation resistance
- Typically supplied in solution annealed condition (+A)
St17-13W (GE Specification) Applications
- Classification: Warm-worked austenitic stainless steel (GE proprietary)
- Applications: Critical rotating components in gas turbines, especially GE designs
- Key Features:
- Enhanced strength through warm working
- Rp0.2 ≥ 440 MPa in warm-worked condition
- Optimized tungsten content for creep resistance
- Typically supplied in warm-worked condition (+HT)
Chemical Composition (%)
| Element | X12CrNiWTiB16-13 / 1.4962 |
St17-13W (GE NB 00144) |
Similar Grades |
|---|---|---|---|
| C | 0.08-0.16 | 0.08-0.15 | 0.08-0.20 |
| Si | ≤1.00 | ≤0.80 | ≤1.00 |
| Mn | ≤2.00 | ≤1.00 | ≤2.00 |
| P | ≤0.045 | ≤0.035 | ≤0.045 |
| S | ≤0.015 | ≤0.005 | ≤0.015 |
| Cr | 15.0-17.0 | 15.50-17.50 | 15.0-18.0 |
| Ni | 12.0-14.0 | 13.00-14.50 | 12.0-15.0 |
| W | 2.0-3.0 | 2.50-3.00 | 2.0-3.5 |
| Ti | 5×C min, ≤0.80 | 5×C min, ≤0.85 | 5×C min, ≤1.00 |
| B | 0.003-0.010 | ≤0.0060 | 0.003-0.010 |
| Mo | ≤0.50 | ≤0.50 | ≤1.00 |
| V | ≤0.10 | ≤0.10 | ≤0.20 |
Note: St17-13W has stricter sulfur control (≤0.005%) compared to standard grades
Material Properties
Room Temperature Mechanical Properties
| Property | 1.4962 / X12CrNiWTiB16-13 | St17-13W (GE Spec) |
|---|---|---|
| 0.2% Proof Strength (MPa) | 240-400 (+A) | 440-650 (+HT) |
| Tensile Strength (MPa) | 540-740 (+A) | ≥590 (+HT) |
| Elongation A5 (%) | ≥35 (+A) | ≥20 (+HT) |
| Impact Energy (J) | ≥80 | ≥70 |
| Hardness (HB) | 160-220 (+A) | 180-240 (+HT) |
High-Temperature Mechanical Properties (650°C)
| Property | 1.4962 / X12CrNiWTiB16-13 | St17-13W (GE Spec) |
|---|---|---|
| 0.2% Proof Strength (MPa) | ≥180 | ≥220 |
| Tensile Strength (MPa) | ≥300 | ≥350 |
| Elongation A5 (%) | ≥25 | ≥18 |
Creep and Rupture Properties
1.4962 / X12CrNiWTiB16-13 Creep Performance
Creep Rupture Strength at 650°C:
- 10,000 hours: ≥120 MPa
- 100,000 hours: ≥90 MPa
Creep Rate: Typically <5×10⁻⁸ %/h at 650°C under 100 MPa stress
St17-13W Creep Performance
- Shows superior creep resistance compared to standard grades
- 100,000 hour rupture strength at 650°C typically ≥100 MPa
- Warm working enhances creep resistance at intermediate temperatures
Physical Properties
| Property | 1.4962 / X12CrNiWTiB16-13 |
|---|---|
| Density (g/cm³) | 7.9 |
| Thermal Conductivity (W/m·K) | 15 (at 20°C), 22 (at 700°C) |
| Specific Heat (J/kg·K) | 500 (at 20°C), 650 (at 700°C) |
| Thermal Expansion (10⁻⁶/K) | 16.0 (20-100°C), 18.5 (20-700°C) |
| Electrical Resistivity (Ω·m) | 0.95 × 10⁻⁶ |
| Elastic Modulus (GPa) | 195 (at 20°C), 150 (at 700°C) |
Heat Treatment
1.4962 / X12CrNiWTiB16-13 Heat Treatment
Solution Annealing (+A):
- Temperature: 1050-1150°C
- Cooling: Rapid cooling (water quenching preferred)
- Purpose: Dissolve carbides and achieve homogeneous austenitic structure
Stabilization Annealing (optional):
- Temperature: 850-950°C
- Cooling: Air cooling
- Purpose: Precipitate TiC and improve creep resistance
St17-13W (GE Specification) Processing
Warm Working (+HT):
- Working temperature: Typically 500-700°C
- Degree of deformation: Proprietary to GE
- Results in enhanced strength through work hardening
Final Condition: Warm Worked (+HT) per GE specifications
Processing Performance
Forging and Hot Working
- Recommended hot working temperature range: 1150-900°C
- Should be cooled rapidly after hot working to prevent carbide precipitation
- Warm working (for St17-13W) performed at 500-700°C
Machinability
- Machinability rating: ~40% of free-cutting steels
- Recommended tools: Carbide tools with chip breakers
- Cutting speeds: 20-40 m/min for turning operations
- Requires rigid setups due to work hardening tendency
Welding Characteristics
- Weldability: Fair with proper precautions
- Recommended Processes: GTAW (TIG), PAW (plasma arc)
- Preheat: Generally not required but 100-150°C helpful
- Post-Weld Heat Treatment: Full solution annealing recommended for critical applications
- Filler Metals: Matching composition or higher alloy grades (e.g., Ni-base alloys)
Microstructural Requirements
- Austenitic Structure: Fully austenitic after solution treatment
- Carbide Precipitation: Controlled distribution of TiC and M23C6
- Grain Size: ASTM 4-6 typically specified
- Delta Ferrite: Generally not permitted
- Inclusions: Controlled per ASTM E45 (Type A <2, Type B <1.5)
Equivalent Grades
| Country/Standard | Equivalent Grade |
|---|---|
| Germany (DIN) | 1.4962, X12CrNiWTiB16-13 |
| USA (GE Spec) | St17-13W |
| USA (ASTM/UNS) | S66286 |
| Japan (JIS) | SUH660 |
| China (GB) | 1Cr15Ni36W3Ti |
| Russia (GOST) | ЭИ787 |
| Europe (EN) | X12CrNiWTiB16-13 |
Quality Control and Testing Requirements
- Chemical Analysis: Melt analysis required for all specified elements
- Mechanical Testing:
- Tensile, impact, hardness testing required
- Testing from center of cross-section for St17-13W
- Non-Destructive Testing:
- Ultrasonic testing for critical applications
- Dye penetrant inspection for surface defects
- High-Temperature Testing:
- Elevated temperature tensile tests at service temperatures
- Creep rupture testing for qualification
Recent Developments and Modifications
Recent updates to St17-13W specification (as seen in the GE document) include:
- Stricter control of sulfur content (≤0.005%)
- Modified tungsten range (2.50-3.00%)
- Updated mechanical property requirements
- Enhanced documentation requirements (EN 10204 Type 3.1)