15-7 PH
Material Data Sheet
Type 15-7 Mo is a semi-austenitic precipitation-hardening stainless steel that provides high strength and hardness, good corrosion resistance, and minimum distortion on heat treatment. It is easily formed in the annealed condition and develops an effective balance of properties by simple aging heat treatments.
In the heat-treated condition, Type 15-7 Mo provides excellent mechanical properties at temperatures up to 900°F (482°C). Its corrosion resistance is superior to that of the hardenable straight chromium types. In some environments, corrosion resistance approximates that of the austenitic chromium-nickel stainless steels.
15-7 Mo is weldable by common fusion and resistance methods; however, this particular alloy is generally considered to have poorer weldability compared to more common PH grades (17-4 PH) due to the high Al content of this alloy, which degrades penetration and enhances weld slag formation during arc welding.
PH 15-7 Mo Stainless Steel requires three essential steps in heat treating:
- Austenite conditioning
- Cooling to transform the austenite to martensite
- Precipitation hardening
15-7 Mo is typically supplied from the mill in Condition A. After fabrication, an austenite conditioning treatment is followed by a transformation treatment to either Condition T or Condition R100. Then the material is precipitation hardened to either Condition TH 1050 or Condition RH 950 to develop fully useable properties.
To obtain the highest mechanical properties in this alloy, Condition A is transformed to martensite at the mill by cold reduction to Condition C. After fabrication by the user, hardening to Condition CH 900 is accomplished with a single low-temperature heat treatment.
| Element | Content (%) |
|---|---|
| Iron, Fe | 69.58 – 76.75 |
| Chromium, Cr | 14.0 – 16.0 |
| Nickel, Ni | 6.5 – 7.75 |
| Molybdemum, Mo | 2.0 – 3.0 |
| Manganese, Mn | ≤ 1.0 |
| Silicon, Si | ≤ 1.0 |
| Aluminum, Al | 0.75 – 1.5 |
| Carbon, C | ≤ 0.09 |
| Sulfur, S | 0.04 |
| Phosphorus, P | ≤ 0.04 |
| Properties | Metric | English |
|---|---|---|
| Density | 7.8 g/cm3 | 0.282 lbs/in3 |
| Melting Point | 1400 – 1450°C | 2550 – 2640°F |
| Properties | Metric | English |
|---|---|---|
| Hardness, Rockwell B | 88 | 88 |
| Tensile Strength, Ultimate | 896 MPa | 130000 psi |
| Tensile Strength, Yield | 372 MPa | 54000 psi |
| Elongation at Break | 35% | 35% |
| Modulus of Elasticity | 200 GPa | 29000 ksi |
| Elastic Modulus | 190 – 210 GPa | 27557 – 30458 ksi |
| Poisson’s Ratio | 0.27 – 0.30 | 0.27 – 0.30 |
Stainless Steel 15-7 PH is used in the following application areas:
- Springs
- Diaphragms
- Retaining rings
- Aircraft bulkheads
- Welded and brazed honeycomb panels
- Applications requiring high strength at elevated temperatures
