07Cr15Ni7Mo2Al (15-7Mo Equivalent) High Strength Stainless Steel
07Cr15Ni7Mo2Al (15-7Mo Equivalent) High Strength Stainless Steel | GB/T 4237 Data
Complete material properties of 07Cr15Ni7Mo2Al (formerly 0Cr15Ni7Mo2Al) according to GB/T 4237: chemical composition, mechanical and physical properties, international equivalents, applications, and processing guidance.
Hot rolling, cold rolling, solution annealing, aging (TH565, RH950), cold working, forming, machining, welding (with caution)
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07Cr15Ni7Mo2Al High Strength Stainless Steel Introduction
07Cr15Ni7Mo2Al (0Cr15Ni7Mo2Al) is a semi-austenitic precipitation hardening stainless steel specified in GB/T 4237 for hot-rolled plates, sheets and strips. It combines good formability in the solution-treated condition with extremely high strength after a simple aging treatment. The alloy contains chromium, nickel, molybdenum and aluminium; the strengthening mechanism relies on the precipitation of Ni-Al intermetallic compounds during aging after a martensitic transformation.
This grade offers outstanding tensile strength (up to 1310 MPa after RH950 treatment) together with corrosion resistance comparable to AISI 304 in many environments. It also exhibits good fatigue properties and oxidation resistance up to about 450°C. Typical delivery conditions are solution-annealed (Condition A), but TH565 or RH950 heat-treated states can be agreed upon.
- High strength and hardness with retained ductility
- Excellent fatigue performance
- Corrosion resistance similar to Type 304
- Good formability in the annealed condition
- Weldable with specific procedures
07Cr15Ni7Mo2Al High Strength Stainless Steel Chemical Composition
Typical chemical composition as specified in GB/T 4237 for grade 07Cr15Ni7Mo2Al. The balanced element is iron. This precipitation hardening steel relies on the simultaneous presence of aluminium and molybdenum to achieve fine intermetallic precipitation during aging.
| Chemical Element | Required Value | Remarks |
|---|---|---|
| C | ≤0.09 | % |
| Si | ≤1.00 | % |
| Mn | ≤1.00 | % |
| P | ≤0.040 | % |
| S | ≤0.030 | % |
| Cr | 14.00 – 16.00 | % |
| Ni | 6.50 – 7.75 | % |
| Mo | 2.00 – 3.00 | % |
| Al | 0.75 – 1.50 | % |
07Cr15Ni7Mo2Al High Strength Stainless Steel Thermal and Electrical Properties
Typical physical properties for 07Cr15Ni7Mo2Al (equivalent to UNS S15700). Values are representative for the alloy in the solution treated condition unless otherwise noted. Thermal conductivity and expansion vary slightly with heat treatment.
| Property | Typical Value | Unit | Test Conditions |
|---|---|---|---|
| Density (ρ) | 7.80 | g/cm³ | At 20°C |
| Elastic modulus (E) | 203 | GPa | At 20°C, solution treated |
| Shear modulus (G) | 78 | GPa | Calculated at 20°C |
| Poisson's ratio (ν) | 0.30 | -- | Room temperature |
| Thermal expansion (α) | 15.3 | 10⁻⁶/K | 20–100°C |
| Thermal expansion (α) | 16.1 | 10⁻⁶/K | 20–200°C |
| Thermal expansion (α) | 16.8 | 10⁻⁶/K | 20–300°C |
| Thermal expansion (α) | 17.4 | 10⁻⁶/K | 20–400°C |
| Thermal expansion (α) | 18.1 | 10⁻⁶/K | 20–500°C |
| Thermal conductivity (λ) | 15.1 | W/(m·K) | At 100°C |
| Thermal conductivity (λ) | 16.3 | W/(m·K) | At 200°C |
| Thermal conductivity (λ) | 17.6 | W/(m·K) | At 300°C |
| Thermal conductivity (λ) | 18.8 | W/(m·K) | At 400°C |
| Thermal conductivity (λ) | 19.7 | W/(m·K) | At 500°C |
| Specific heat capacity (cp) | 460 | J/(kg·K) | At 20°C |
| Electrical resistivity (ρe) | 0.79 | µΩ·m | At 20°C |
07Cr15Ni7Mo2Al High Strength Stainless Steel Mechanical Properties
Minimum or maximum required values according to GB/T 4237 for 07Cr15Ni7Mo2Al. The properties depend strongly on the heat treatment condition. For flat products the values apply to the thickness range usually up to 100 mm. Tensile testing at room temperature.
| Property | Required Value | Unit | Test Conditions |
|---|---|---|---|
| Yield strength (Rp0.2) | ≤380 | MPa | Solution treated (Condition A) |
| Yield strength (Rp0.2) | ≥1030 | MPa | TH565 (solution treated + 565°C aged) |
| Yield strength (Rp0.2) | ≥1170 | MPa | RH950 (solution treated + sub-zero + 510°C aged) |
| Tensile strength (Rm) | ≤1030 | MPa | Solution treated (Condition A) |
| Tensile strength (Rm) | ≥1210 | MPa | TH565 |
| Tensile strength (Rm) | ≥1310 | MPa | RH950 |
| Elongation (A) | ≥20 | % | Solution treated (Condition A) |
| Elongation (A) | ≥5 | % | TH565 |
| Elongation (A) | ≥4 | % | RH950 |
| Hardness (HRC) | ≤20 | HRC | Solution treated (Condition A) |
| Hardness (HRC) | ≥39 | HRC | TH565 |
| Hardness (HRC) | ≥42 | HRC | RH950 |
07Cr15Ni7Mo2Al High Strength Stainless Steel Fully Equivalent International Grades and Replacement Recommendations
| Country/Region | Standard | Designation | Remarks |
|---|---|---|---|
| China | GB/T 4237 | 07Cr15Ni7Mo2Al | Precipitation hardening Cr-Ni-Mo-Al steel |
| USA | ASTM A693 | Grade 632 (UNS S15700) | Also known as 15-7Mo, available as plate, sheet and strip |
| Japan | JIS G4304 | SUS631J1 | Equivalent grade in JIS for hot-rolled stainless steel plate |
| Europe | EN 10088-3 | X8CrNiMoAl15-7-2 (1.4532) | Covered under semi-finished products, bars and forgings |
07Cr15Ni7Mo2Al High Strength Stainless Steel Application Introduction
07Cr15Ni7Mo2Al combines high mechanical strength, good fatigue resistance and adequate corrosion resistance, making it ideal for weight- and space-critical components that operate under high stress in mildly corrosive environments.
- Solution treated (Condition A): excellent formability for complex shapes.
- After aging (TH565 or RH950): tensile strength exceeds 1200 MPa with hardness over 39 HRC, suitable for structural and spring applications up to about 400°C.
- Welding is possible with matching filler metals and post-weld heat treatment; avoid carbon pick-up.
Product Applications: Flat springs, leaf springs, wave springs and Belleville washers, Metal bellows and expansion joints, Diaphragms and pressure-sensitive membranes, High-strength bolts, studs and anchor nuts, Valve stems, seats and pump shafts, Clamps and sealing rings in corrosive environments, Honeycomb core and sandwich panels for aerospace
Processed into products: Aircraft structural brackets and fittings, Landing gear torque links, Fuel system diaphragm plates, Welded hydraulic reservoirs, Industrial spring washers and retaining rings, Flexible couplings for chemical pumps, Collets and tool holders, High-cycle fatigue specimens and test fixtures
Application industries: Aerospace engineering (airframe, engine components, fasteners), Chemical and petrochemical processing (valves, seals, springs in corrosive media), Medical devices (surgical instruments, implants requiring high strength), Precision machinery and instrumentation (elastic elements, force sensors), Automotive and racing (high-performance springs, exhaust components)
07Cr15Ni7Mo2Al High Strength Stainless Steel Similar or Alternative Materials with Comparable Performance
| Country/Region | Standard | Designation | Remarks |
|---|---|---|---|
| USA | ASTM A693 | Grade 630 (17-4PH, S17400) | Martensitic precipitation hardening; higher Cr, Cu, Nb; no Al; good strength and corrosion resistance |
| USA | ASTM A564 | Grade XM-25 (15-5PH, S15500) | Martensitic PH steel with similar strength and toughness, no Mo or Al |
| USA | ASTM A693 | Grade 631 (17-7PH, S17700) | Semi-austenitic PH steel without Mo; lower strength than 07Cr15Ni7Mo2Al after aging, similar formability |
| USA | AMS 5529 | PH 13-8Mo (S13800) | Martensitic PH steel with higher strength and fracture toughness, containing Mo and Al |
Notes:
- Heat treatment must be performed in a protective atmosphere or vacuum to prevent surface oxidation and carbon contamination.
- For TH565 condition: solution treat at 1050 ±10°C, air cool (or water quench), then age at 565 ±10°C for 90 minutes, air cool.
- For RH950 condition: solution treat as above, cool to -73°C within 1 hour, hold 8 hours, then age at 510 ±10°C for 60 minutes, air cool.
- Weld procedures should use low heat input; filler metal matching the base metal composition or AWS ER3556 may be considered; post-weld solution annealing and aging are recommended to restore properties.
- In the fully hardened condition the alloy is not recommended for further cold forming operations; machining should be carried out with carbide tools and adequate cooling.
- These data are for reference only; always refer to the official standard or material certificate for critical applications.
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