Stainless 13-8Mo · UNS S13800
Stainless 13-8Mo (S13800): composition, properties, fittings and flanges
Stainless 13-8Mo (S13800) is Martensitic precipitation-hardening stainless steel with molybdenum. Stainless 13-8Mo is specified at Chromium 12.25 - 13.25, Nickel 7.50 - 8.50, Molybdenum 2.00 - 2.50. 13-8Mo precipitates NiAl rather than copper, giving the highest strength of the common PH grades plus better stress corrosion…
- UNS
- S13800
- W. Nr.
- -
- Density
- 7.83 g/cm³ (0.283 lb/in³)
- Key strength
- 1550 MPa / 225 ksi
Identification and standards
| Short form | Stainless 13-8Mo · UNS S13800 |
|---|---|
| Classification | Martensitic precipitation-hardening stainless steel with molybdenum |
| UNS | S13800 |
| Werkstoff number | - |
| Material family | Stainless Steel |
Chemical composition
| Element | Composition (wt %) | Why it is there |
|---|---|---|
| Chromium (Cr) | 12.25 - 13.25 | Corrosion resistance |
| Nickel (Ni) | 7.50 - 8.50 | Austenite retention and NiAl hardening |
| Molybdenum (Mo) | 2.00 - 2.50 | Pitting and SCC resistance |
| Aluminium (Al) | 0.90 - 1.35 | NiAl precipitation |
| Carbon (C) | 0.05 max | - |
| Manganese (Mn) | 0.20 max | - |
| Silicon (Si) | 0.20 max | - |
| Iron (Fe) | Balance | Matrix |
Note Single figures are maximum limits unless shown as a range. Always confirm against the heat-specific EN 10204 3.1 certificate supplied with your order.
Mechanical properties
| Tensile strength, min (H950) | 1550 MPa / 225 ksi |
|---|---|
| 0.2 % yield strength, min (H950) | 1413 MPa / 205 ksi |
| Elongation in 2 in, min (H950) | 10 % |
| Typical hardness, H950 | 43 - 48 HRC |
| SCC resistance vs 17-4PH | Better in chloride environments |
Warning Values depend on product form, section thickness and heat treatment. Larger sections generally achieve lower strength than thin product; always design against the applicable code allowable stress rather than these figures.
Physical properties
| Density | 7.83 g/cm³ (0.283 lb/in³) |
|---|---|
| Melting range | 1400 - 1440 °C (2550 - 2625 °F) |
| Modulus of elasticity | 195 GPa (28.3 x 10⁶ psi) |
| Thermal conductivity at 20 °C | 17.2 W/m·K |
| Mean coefficient of thermal expansion, 20-100 °C | 10.4 µm/m·°C |
| Specific heat capacity | 460 J/kg·K |
Specifications by product form
| Forgings & flanges | ASTM A564 / A705 Type XM-13 (UNS S13800) |
|---|---|
| Butt weld fittings | To order against ASTM A564 chemistry |
| Seamless pipe & tube | To order |
| Plate / sheet / strip | ASTM A693 Type XM-13 |
| Bar / rod | ASTM A564 / A705 · NACE MR0175 |
| Welding consumables | Matching 13-8Mo filler |
| UNS / EN / China | UNS S13800 |
Product forms available
Hangbo supplies this grade in the following forms. Sizes outside the listed range can often be produced to order.
- Forged flanges blanks and finished flanges to ASME B16.5, B16.47 Series A/B and B16.36
- Butt weld elbows, tees, reducers, caps and stub ends to ASME B16.9 and MSS SP-43
- Seamless pipe and tube to the applicable ASTM / ASME pipe specification
- Forged rings, discs and hubs machined to your drawing
Typical applications
- Aerospace fittings, actuators and structural hardware
- Sour service and offshore components needing NACE compliance
- High-strength fasteners and springs
- Nuclear and medical instrumentation parts
Welding, forming and machining
- Welding
- Weld with matching filler in the solution-annealed condition, then age. The alloy is normally supplied vacuum remelted for critical aerospace work.
- Heat treatment
- Solution anneal at 925 °C, then age at 510 - 620 °C depending on the specified H950 to H1150 condition.
- Hot and cold forming
- Hot work in the range stated by the mill for this grade, then re-solution or re-age before final machining so that the delivered condition matches the certificate.
- Machining
- Machine with sharp carbide or high-speed steel tooling, positive rake, constant feed and ample coolant. Never dwell - the surface work-hardens quickly.
Buy Stainless 13-8Mo from Hangbo
Material is supplied with full heat-number traceability, solution annealing or ageing performed under calibrated furnace control, and an EN 10204 3.1 certificate covering chemical analysis, mechanical properties, heat treatment records and the agreed NDT scope. Positive material identification and third party inspection and test reports from SGS are available for critical service.