15-7 Mo is a semi-austenitic precipitation hardening stainless steel that combines high strength, excellent corrosion resistance, and minimal distortion during heat treatment. In the annealed condition, this alloy offers excellent formability and can achieve an outstanding combination of mechanical properties through simple heat treatment processes. It is widely used in aerospace components requiring high-temperature strength, such as retaining rings, springs, diaphragms, and aircraft bulkheads.
High Strength and Hardness
Yield strength can reach up to 260 ksi (1,793 MPa) in the CH 900 condition.
Excellent Corrosion Resistance
Superior corrosion resistance compared with 410, 420, and 431 stainless steels in the TH 1050 and RH 950 conditions.
Minimal Heat Treatment Distortion
Excellent dimensional stability, making it ideal for precision components.
Good Formability
In the annealed condition, its forming characteristics are similar to 301 stainless steel.
Stable High-Temperature Performance
Suitable for structural components operating under elevated temperature conditions.
Thermal conductivity (TH 1050 state)
Thermal expansion coefficient (state A)
Elastic Modulus: 29.0 × 10³ ksi (200 GPa)
Austenite Conditioning
Prepares the material for subsequent phase transformation.
Cooling Transformation
Transformation of austenite into martensite (T Condition or R100 Condition).
Precipitation Hardening
Achieves the final service conditions of TH 1050 or RH 950.
Condition A material can be cold worked to transform into Condition C (martensitic structure).
After machining, a single low-temperature aging treatment can further harden the material to the CH 900 condition.
Condition A:
Formability is comparable to 301 stainless steel. It exhibits rapid work hardening, and intermediate annealing may be required for deep drawing or complex forming operations.
Springback:
Similar to 301 stainless steel.
Condition C:
The material has extremely high hardness and strength; appropriate machining and forming techniques are required.
Compatible with conventional fusion welding and resistance welding processes, with better weldability than 17-4 PH stainless steel.
The high aluminum content may reduce weld penetration and promote slag formation during welding.
Post-weld austenite conditioning and precipitation hardening heat treatment are required to achieve maximum strength.
Recommended Welding Filler Metals: W 15-7 Mo or W 17-7 PH
The corrosion resistance of TH 1050 and RH 950 conditions is superior to standard hardenable stainless steels such as Type 410, 420, and 431 stainless steels.
Corrosion resistance is slightly lower than that of 304 stainless steel.
Aerospace Applications:
Aircraft bulkheads
Honeycomb sandwich panels
Precision Components:
Retaining rings
Springs
Diaphragms
High-Temperature Components:
Aircraft structural components requiring high strength at elevated temperatures
Welded and Brazed Components:
Welded and brazed honeycomb panels
15-7 Mo stainless steel provides an ideal material solution for aerospace and precision manufacturing applications through its unique semi-austenitic precipitation hardening characteristics. Its excellent combination of high strength, good corrosion resistance, and minimal distortion during heat treatment makes it a preferred material for demanding engineering applications.
Whether in the ultra-high-strength CH 900 condition or the balanced-performance TH 1050 condition, this alloy delivers reliable performance to meet a wide range of engineering requirements.