PH 13‑8 Mo is a precipitation‑hardening martensitic stainless steel designated as ASTM XM‑13, UNS S13800, and EN 1.4534. It offers a superior combination of high strength, excellent fracture toughness, and good resistance to stress corrosion cracking in chloride environments up to approximately 300 °C. The alloy is strengthened by precipitation of nano‑scale intermetallic phases during a single‑step ageing treatment, achieving tensile strengths above 1500 MPa while retaining ductility. Typical industries include aerospace, chemical processing, oil & gas, nuclear, and high‑performance engineering where high specific strength and corrosion resistance are critical. It is widely specified for critical fasteners, structural components, and valve parts in severe service conditions.
Equivalent Grades & Standards
| Standard / System | Grade / Designation |
|---|---|
| ASTM | XM‑13 per ASTM A564, A693, A705 |
| AMS | AMS 5629 (bar, wire, forgings), AMS 5864, AMS 5934 |
| EN / DIN | 1.4534 / X3CrNiMoAl 13‑8‑2 per EN 10088‑3 |
| UNS | S13800 |
| JIS | No direct equivalent; closest SUS 632 (0Cr13Ni8Mo2Al) |
| GOST | No direct equivalent; closest 07Kh16N6 |
Typical Applications
Aerospace:
Oil & Gas:
Chemical Processing:
Nuclear:
Medical:
Power Generation:
Supply Range
| Form | Dimensions |
|---|---|
| Round Bar | Dia. 8 mm – 350 mm (0.31″ – 14″) |
| Flat Bar | Thk. 4–60 mm × W 15–300 mm |
| Plate / Sheet | Thk. 0.5–60 mm × W up to 2000 mm |
| Seamless Tube | OD 10–200 mm × WT 1.0–20 mm |
| Wire | Dia. 0.5–10 mm (0.02″–0.39″) |
| Forgings | OD up to 1800 mm; weight up to 4000 kg |
Chemical Composition
Per ASTM A564 Grade XM‑13 (weight %):
| C | Mn | Si | P | S | Cr | Ni | Mo | Al | N | Fe |
|---|---|---|---|---|---|---|---|---|---|---|
| ≤0.05 | ≤0.10 | ≤0.10 | ≤0.010 | ≤0.008 | 12.25–13.25 | 7.50–8.50 | 2.00–2.50 | 0.90–1.35 | ≤0.01 | Bal. |
Tight control of carbon and nitrogen ensures high toughness and consistent precipitation hardening response.
Mechanical Properties
| Condition | Tensile Strength (MPa) | Yield Strength 0.2% (MPa) | Elongation (%) | Hardness (HRC) |
|---|---|---|---|---|
| Solution Annealed (Condition A) | ≈ 1035 | ≈ 790 | ≥ 17 | ~33 |
| H950 (Age 510°C) | ≥ 1520 | ≥ 1410 | ≥ 10 | 44–48 |
| H1000 (Age 538°C) | ≥ 1310 | ≥ 1210 | ≥ 12 | 39–43 |
| H1050 (Age 566°C) | ≥ 1170 | ≥ 1070 | ≥ 15 | 35–39 |
Solution annealing is performed at 927 °C ± 15 °C followed by oil or air cooling. Subsequent ageing at the designated temperature develops the unique precipitation‑strengthened structure. The alloy retains excellent toughness down to cryogenic temperatures and offers superior fatigue resistance compared to conventional martensitic stainless steels.
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