1.4938, X12CrNiMoV12-3, UNS S64152, Z12CNDV12-03
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 1.4938, X12CrNiMoV12-3, UNS S64152, Z12CNDV12-03?
High-temperature martensitic stainless steels are critical materials for power generation and aerospace applications, offering exceptional creep resistance, oxidation resistance, and mechanical properties at elevated temperatures. This guide provides a comprehensive technical analysis of 1.4938 (X12CrNiMoV12-3) and its equivalent grades across major OEM specifications.
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.
For manufacturers and researchers, understanding the detailed requirements of these materials is essential for proper application and processing. The comprehensive testing and qualification procedures outlined in specifications ensure that only material meeting the highest quality standards is used in critical components.
| Designation | Structure | Trade Name / Alloy | OEM Part Numbers | EN Number |
|---|---|---|---|---|
| X122MV | Martensitic | XM-32 | Siemens 29A, 29H, MAT239204, TLV 9251 01 Alstom |
S64152 |
Applications
X12CrNiMoV12-3, 1.4938 Applications
- Classification: 12%Cr martensitic stainless steel with Mo-V-Nb additions
- Key Specifications:
- GE/Alstom: STV M14101, STV M23004, STV M23022
- Siemens: 29A/H, MAT239204, TLV 9251 01
- MAN: QSTD-51-231/000
- AMS: 5718, 5719
- Applications:
- Gas and steam turbine blades
- Compressor discs and rotors
- High-temperature fasteners
- Aerospace components
- Key Features:
- Excellent creep resistance up to 600°C
- Good oxidation resistance
- Typically supplied in quenched and tempered condition (+QT)
- Fully martensitic microstructure after heat treatment
Chemical Composition (%)
| Grade | Chemical Composition WT % | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| C | Mn | Si | P | S | Cr | Mo | Ni | V | N | ||
M152 |
0.08-0.13 |
0.50-0.90 | Max 0.35 | Max 0.030 | Max 0.025 | 11.0 - 12.5 | 1.5 - 2.0 | 2.0 - 3.0 | 0.25 - 0.40 | 0.02 - 0.04 | |
X12CrNiMoV12-3 |
0.08 - 0.15 | 0.50-0.90 | Max 0.35 | Max 0.020 | Max 0.015 | 11.0 - 12.5 | 1.5 - 2.0 | 2.0 - 3.0 | 0.25 - 0.40 | 0.02 - 0.04 | |
X12CrNiMoV12-3, 1.4938 |
0.08 - 0.15 | 0.4 - 0.9 | Max 0.5 | Max 0.025 | Max 0.015 | 11.0 - 12.5 | 1.5 - 2.0 | 2.0 - 3.0 | 0.25 - 0.40 | 0.02 - 0.04 | |
X12CrNiMo12, 1.4939, X12CrNiMoN12 |
0.08 - 0.13 | 0.5 - 0.9 | Max 0.35 | Max 0.025 | Max 0.020 | 11.0 - 12.5 | 1.5 - 2.0 | 2.0 - 3.0 | 0.25 - 0.40 | 0.02 - 0.04 | |
X11CrNiMoN12 |
0.08 - 0.15 | 0.4 - 0.9 | Max 0.50 | Max 0.025 | Max 0.015 | 11.0 - 12.5 | 1.5 - 2.0 | 2.0 - 3.0 | 0.25 - 0.40 | 0.02 - 0.04 | |
AMS UNS S64152 |
0.08 - 0.15 | 0.5 - 0.9 | Max 0.35 | Max 0.025 | Max 0.025 | 11.0 - 12.5 | 1.5 - 2.0 | 2.0 - 3.0 | 0.25 - 0.40 | 0.01 - 0.05 | |
Z12CNDV12-03 |
0.08 - 0.15 | 0.5 - 0.9 | Max 0.35 | Max 0.030 | Max 0.015 | 11.0 - 12.5 | 1.5 - 2.0 | 2.0 - 3.0 | 0.25 - 0.40 | 0.02 - 0.04 | |
XM-32 |
0.08 - 0.13 | 0.5 - 0.9 | Max 0.40 | Max 0.030 | Max 0.025 | 11.0 - 12.5 | 1.5 - 2.0 | 2.0 - 3.0 | 0.25 - 0.40 | 0.02 - 0.04 | |
Note: Trace elements (Cu, As, Sb, Sn) are typically controlled to ≤0.10% each
Material Properties
Room Temperature Mechanical Properties
| Property | 1.4938 (QT) | AMS 5719 | GE STV M23004 | Siemens TLV 9251 01 | MAN QSTD-51-231/000 |
|---|---|---|---|---|---|
| 0.2% Proof Strength (MPa) | 785-930 | 785-930 | 785-930 | 785-900 | 785-930 |
| Tensile Strength (MPa) | 900-1100 | 900-1100 | 900-1100 | 900-1100 | 900-1100 |
| Elongation A5 (%) | ≥14 | ≥14 | ≥14 | ≥14 | ≥14 |
| Reduction of Area (%) | ≥40 | ≥40 | ≥40 | ≥40 | ≥40 |
| Impact Energy (J) | ≥40 | ≥40 | ≥40 | ≥40 | ≥40 |
| Hardness (HB) | 270-330 | 270-330 | 270-330 | 270-310 | 270-330 |
High-Temperature Mechanical Properties (600°C)
| Property | 1.4938 | AMS 5719 | GE STV M23004 |
|---|---|---|---|
| 0.2% Proof Strength (MPa) | ≥405 | ≥405 | ≥405 |
| Tensile Strength (MPa) | ≥420 | ≥420 | ≥420 |
| Elongation A5 (%) | ≥18 | ≥18 | ≥18 |
| Reduction of Area (%) | ≥65 | ≥65 | ≥65 |
Creep and Rupture Properties
Creep Performance at 600°C
Creep Rupture Strength:
- 10,000 hours: ≥120 MPa
- 100,000 hours: ≥90 MPa
- Creep Rate: Typically <1×10⁻⁷ %/h under 100 MPa stress
- Larson-Miller Parameter (C=20): ~24 at 100 MPa/10,000h
Oxidation Resistance
- Continuous service: Up to 650°C
- Intermittent service: Up to 700°C
- Weight gain: <2 mg/cm² after 1000h at 600°C
Physical Properties
| Property | 1.4938 / X12CrNiMoV12-3 |
|---|---|
| Density (g/cm³) | 7.8 |
| Thermal Conductivity (W/m·K) | 25 (20°C), 28 (600°C) |
| Specific Heat (J/kg·K) | 460 (20°C), 600 (600°C) |
| Thermal Expansion (10⁻⁶/K) | 10.5 (20-100°C), 12.8 (20-600°C) |
| Electrical Resistivity (Ω·m) | 0.85 × 10⁻⁶ |
| Elastic Modulus (GPa) | 210 (20°C), 170 (600°C) |
Heat Treatment
Standard Heat Treatment
Hardening:
- Temperature: 1000-1050°C
- Quenching: Oil or air cooling
- Must be cooled to ≤100°C to ensure complete martensitic transformation
Tempering:
- Double tempering at 650-720°C
- Minimum tempering time: 2 hours (or 2 min/mm thickness)
- Stress relief after machining: 30-50°C below last tempering temperature
Final Condition: Quenched and Tempered (+QT)
Alternative Heat Treatment Conditions
- +A (Annealed): 850-900°C, slow cooling (for machining)
- +HT (Hardened & Tempered): Single temper at higher temperature (for specific applications)
- +SR (Stress Relieved): 600-650°C after machining
Processing Performance
Forging and Hot Working
- Recommended hot working temperature: 1100-900°C
- Forging reduction ratio: ≥5:1 required
- Post-forging cooling: Slow cooling to prevent cracking
Machinability
- Machinability rating: ~45% of free-cutting steels
- Recommended tools: Carbide tools with positive rake angles
- Cutting speeds: 30-50 m/min for turning operations
- Requires generous use of cutting fluids
Welding Characteristics
- Weldability: Fair with proper precautions
- Recommended Processes: GTAW (TIG), SMAW with matching filler
- Preheat: 200-300°C
- Post-Weld Heat Treatment: Full heat treatment cycle recommended
- Filler Metals: Matching composition or higher alloy grades
Microstructural Requirements
- Martensitic Structure: Fully martensitic after heat treatment
- Delta Ferrite: ≤5% allowed (typically ≤2% preferred)
- Grain Size: ASTM 4 or finer
- Inclusions:
- Type A (Sulfide): ≤2.0
- Type B (Alumina): ≤2.0
- Type C (Silicate): ≤2.0
- Type D (Globular oxide): ≤2.0
- Homogeneity: Must be free from porosity, excessive segregation
Quality Control and Testing Requirements
- Chemical Analysis: Melt and product analysis required
- Mechanical Testing:
- Tensile, impact, hardness testing required
- Testing from 1/4 thickness location
- Ultrasonic testing per SEP 1923 or equivalent
- Magnetic particle inspection for surface defects
Non-Destructive Testing:
High-Temperature Testing:
- Elevated temperature tensile tests
- Creep rupture testing for qualification
Microstructural Examination:
- Delta ferrite content
- Grain size determination
- Inclusion rating
Equivalent Grades and Specifications
| Organization | Specification Numbers | Equivalent Grade Designations |
|---|---|---|
| GE/Alstom | STV M14101, STV M23004, STV M23022 | X12CrNiMoV12-3 |
| Siemens | 29A/H, MAT239204, TLV 9251 01 | 1.4938 |
| MAN | QSTD-51-231/000, TLV1216 | X12CrNiMo12 + QT900 |
| Škoda | TP 0010 | 14Cr12Ni2WMoV |
| AMS | 5718, 5719 | UNS S64152 |
| ASTM | A565 Grade XM-32 | XM-32 |
| DIN | 1.4938 | X12CrNiMoV12-3 |
| EN | - | X12CrNiMoV12-3 |
| GB | 1Cr12Ni2W1Mo1V | 14Cr12Ni2WMoV |
Recent Developments and Modifications
- GE/Alstom: Updated requirements for cleaner steel (lower S, P)
- Siemens: Modified tempering temperature ranges for improved creep resistance
- MAN: Enhanced NDT requirements (UT sensitivity to 0.7mm DSR)
- AMS 5719: Revised delta ferrite limits to ≤5%