13-8PH Stainless Steel (AMS 5629 / AMS 5864)
Tailwind Aerospace Solutions supplies 13-8PH precipitation-hardening stainless steel to AMS 5629, AMS 5864, and AMS 5934 specifications. Known commercially as PH13-8Mo or XM-13 (UNS S13800), this alloy is engineered for applications where standard PH grades like 17-4PH or 15-5PH fall short. It delivers higher strength, superior toughness, and better corrosion resistance in a single heat-treatable package. If your drawing calls out AMS 5629 or AMS 5864, we stock certified material ready to ship with full traceability documentation.
What Makes 13-8PH Different
Not all precipitation-hardening stainless steels are created equal. 13-8PH occupies a specific niche in the PH family, engineered through a more demanding melting process to achieve mechanical properties that 17-4PH and 15-5PH simply can't match in critical applications.
Double-Melt Processing: VIM + VAR (and ESR) for Superior Cleanliness
13-8PH is double-melted, typically starting with Vacuum Induction Melting (VIM) followed by Consumable Electrode Vacuum Melt (CEVM, also called VAR, or Vacuum Arc Remelt). In some cases, a second melt via Electroslag Remelting (ESR) is specified instead. This double-melt process removes inclusions and controls chemistry far more tightly than standard air-melt or single-melt processing, resulting in a cleaner microstructure. That cleanliness directly translates into the alloy's standout transverse toughness, a property that's difficult to achieve consistently in larger bar and plate sections with less rigorously processed alloys.
PH13-8Mo, XM-13, and Other Trade Names
13-8PH goes by several names depending on the specification or industry you're working in, including PH13-8Mo, XM-13, and the ATI 13-8 Supertough® Alloy designation used for the AMS 5934 variant. You may also see it referenced under DMS 2100, HMS 6-1105, or RMS-150 in OEM specific drawings. All of these refer to the same base alloy family under UNS S13800.
UNS S13800 Composition Breakdown
13-8PH's chemistry is built around chromium, nickel, and molybdenum, with aluminum added to enable precipitation hardening:
| Element | Min % | Max % |
|---|---|---|
| Chromium (Cr) | 12.25 | 13.25 |
| Nickel (Ni) | 7.50 | 8.50 |
| Molybdenum (Mo) | 2.00 | 2.50 |
| Aluminum (Al) | 0.90 | 1.35 |
| Nitrogen (N) | 0 | 0.010 |
| Iron (Fe) | Balance | |
The higher nickel and molybdenum content, compared to 17-4PH or 15-5PH, is what gives 13-8PH its superior toughness and corrosion resistance. This comes at a higher material cost, which is why it's typically reserved for applications where those properties are non-negotiable.
Specifications & Certifications
13-8PH is governed by three distinct AMS specifications, each tied to a specific product form. Knowing which spec applies to your part is critical for sourcing the right material.
AMS 5629 covers bar, forgings, wire, extrusions, and flash-welded rings. Under this spec, round bar is limited to 12" maximum diameter, and hex bar is capped at 12" across flats. Stock of any size is available for forgings, rings, or extrusions. A sub-variant, AMS 5629/H1000, covers material produced and precipitation hardened directly to the H1000 condition.
AMS 5864 is the dedicated specification for 13-8PH plate. If your drawing calls for 13-8PH plate stock rather than bar, this is the spec you'll see referenced.
AMS 5934 covers the ATI 13-8 Supertough® Alloy variant. This includes bar, forgings, rings, and extrusions engineered for even greater fracture toughness than standard AMS 5629 material. This variant is typically specified for the most demanding structural applications where crack resistance under cyclic loading is a primary design driver.
13-8PH cross-references to several ASTM standards depending on product form. ASTM A564 covers Type XM-13 bars, wires, and shapes. ASTM A693 applies to sheet, plate, and strip. ASTM A705 governs forgings. These cross-references are especially useful if your purchase order or customer specification references ASTM rather than AMS directly.
Stock Sizes & Shape Limits
13-8PH is stocked in a limited but well-defined range of shapes, each with specific size constraints tied to the AMS 5629 specification.
Round bar is available up to 12 inches in diameter under AMS 5629. Larger sizes may be sourced by special arrangement, subject to agreement on mechanical properties between buyer and seller.
Hex bar follows the same 12 inch maximum, measured across flats. This shape is commonly specified for fastener stock and machined components requiring a hexagonal cross section.
Plate is supplied under AMS 5864 in a range of standard thicknesses. Contact our team for current stock availability and lead times on your required size.
Need 13-8PH Stainless Steel?
Get certified round bar, hex bar, or plate to AMS 5629, 5864, or 5934 specs.
Precipitation Hardening Conditions
H950 Through H1150: Strength vs. Toughness Tradeoffs
13-8PH can be heat treated to a range of precipitation hardening conditions, each balancing strength against toughness and ductility:
| Condition | Aging Temperature |
|---|---|
| H950 | 950°F ± 10°F (510°C ± 6°C) |
| H1000 | 1000°F ± 10°F (538°C ± 6°C) |
| H1025 | 1025°F ± 10°F (552°C ± 6°C) |
| H1050 | 1050°F ± 10°F (566°C ± 6°C) |
| H1100 | 1100°F ± 10°F (593°C ± 6°C) |
| H1150 | 1150°F ± 10°F (621°C ± 6°C) |
Lower temper conditions like H950 deliver the highest strength and hardness but reduced ductility. Higher temper conditions like H1150 sacrifice some strength in exchange for improved toughness and elongation. Your application's load conditions and fracture tolerance requirements should guide which condition to specify.
Source 13-8PH from Tailwind Aerospace Solutions
Tailwind Aerospace Solutions stocks 13-8PH stainless steel to AMS 5629, AMS 5864, and AMS 5934 specifications, with full material certifications and traceability documentation available on every order. Whether you need round bar, hex bar, or plate, our team can help you confirm the right spec and condition for your application. Contact us today for a quote.
Frequently Asked Questions
13-8PH is a martensitic precipitation-hardening stainless steel (UNS S13800) known for its high strength, superior toughness, and good corrosion resistance. It's double melted using Vacuum Induction Melting (VIM) and Vacuum Arc Remelting (VAR), or in some cases Electroslag Remelting (ESR), which gives it a cleaner microstructure than many other PH grades.
13-8PH generally offers better toughness and more consistent mechanical properties in larger cross sections than 17-4PH, largely due to its double melt processing. 17-4PH is more widely available and typically lower cost, making it suitable for less demanding applications, while 13-8PH is reserved for higher performance requirements like rocket engine and nuclear components.
AMS 5629 is the aerospace material specification covering 13-8PH bar, forgings, wire, extrusions, and flash welded rings. Round bar under this spec is limited to 12 inches maximum diameter, and hex bar is limited to 12 inches across flats.
AMS 5864 is the specification that covers 13-8PH plate. If your drawing calls for 13-8PH in plate form, this is the applicable spec.
"Supertough" refers to the ATI 13-8 Supertough® Alloy, a variant of 13-8PH covered under AMS 5934. This version is engineered for even greater fracture toughness than standard AMS 5629 material, typically for structural applications with high cyclic loading and crack resistance requirements.
13-8PH is commonly used in aerospace, nuclear, and rocket engine components where high strength, toughness, and corrosion resistance are all required simultaneously. It's also used in other applications requiring reliable mechanical performance in larger bar or plate sections.
13-8PH can be aged to a range of precipitation hardening conditions from H950 to H1150. Lower temperature conditions like H950 produce higher strength and hardness with lower ductility, while higher temperature conditions like H1150 provide improved toughness and elongation at somewhat lower strength.
Yes. All 13-8PH stainless steel supplied by Tailwind Aerospace Solutions includes full material certifications and traceability documentation to support aerospace and defense quality requirements.
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