Project Description
15-5PH, designated as UNS S15500 and ASTM XM-12, is a martensitic precipitation-hardening stainless steel containing approximately 15% chromium, 5% nickel, and 3.5% copper. Engineered as the ferrite-free upgrade of 17-4PH, 15-5PH eliminates delta ferrite via a refined Cr/Ni balance, delivering superior transverse toughness, uniform through-thickness properties in large sections, and dramatically improved forgeability. Covered under AMS 5659 and ASTM A564/A705, the alloy achieves its strength through a simple single-step low-temperature aging treatment (480–620°C) that precipitates nanoscale epsilon-Cu phases without the distortion associated with martensitic quench-and-temper steels. Widely adopted across aerospace, oil & gas, and chemical processing, 15-5PH is the go-to material for landing gear components, high-pressure valve bodies, downhole instrumentation, pump shafts, and structural fasteners where multi-axial toughness and corrosion resistance approaching Type 304 are non-negotiable.
15-5PH / S15500 — Overview
15-5PH (UNS S15500, XM-12) is a martensitic precipitation-hardening stainless steel developed to eliminate the transverse ductility shortfall of 17-4PH in heavy cross-sections. By tightening the chromium-to-nickel ratio to suppress delta ferrite formation, the alloy achieves consistently high toughness in both longitudinal and transverse directions—an essential property for oil & gas pressure-containing components subjected to multi-axial stress. The copper-niobium precipitation system enables a six-tier aging matrix (H900 through H1150) spanning tensile strengths from over 1310 MPa down to 931 MPa, allowing designers to dial in the precise strength-toughness balance for each application. SHUNFU METAL supplies 15-5PH bar, forging stock, and machined components under an integrated ISO 9001 and API Q1 quality management system, ensuring full melt-to-delivery traceability, in-house spectrometric verification of every heat, and documented conformance to AMS 5659, ASTM A564, and EN 10088-3.
Equivalent Standards of 15-5PH / S15500
| Standard | Specification | Grade |
|---|---|---|
| ASTM | A564 / A705 | XM-12 |
| AMS | 5659 / 5862 | 15-5PH |
| UNS | S15500 | S15500 |
| AISI | — | 15-5PH |
| EN | 10088-3 | 1.4545 / X5CrNiCuNb15-5 |
| DIN | EN 10088-3 | X5CrNiCuNb15-5 |
| GOST | 5632-72 | 03Х17Н4К4Нб / 08KH15N5D2T |
| JIS | G 4303 | SUS15-5PH |
| GB | GB/T 1220 / 20878 | 05Cr15Ni5Cu4Nb |
| AFNOR | NF EN 10088-3 | Z5CNU15-5 |
Oil & Gas Applications of 15-5PH
In the petroleum sector, 15-5PH is specified wherever high strength (up to 190 ksi UTS in H900), toughness at low temperature, and reliable resistance to produced-fluid corrosion must coexist in a single material. Components manufactured by SHUNFU METAL from 15-5PH bar and forging stock serve across the exploration, production, and refining value chain:
Downhole Tools
MWD/LWD housings, rotary steerable mandrels, perforating gun carriers, packer bodies, wireline instrument cases
Valves & Valve Trim
Gate valve stems, ball valve trunnions, choke stems, needle valve spindles, high-pressure seat rings
Pumps & Compressors
Multistage pump shafts, plunger rods, impeller wear rings, compressor valve plates, reciprocating rods
Wellhead & Xmas Tree
Tubing hanger necks, lockdown screws, gate guides, actuator stems, instrument flanges
BOP & Pressure Control
Ram shafts, bonnet bolts, annular packer pistons, hydraulic actuator rods, shear blade holders
Fasteners
High-strength studs, tension bolts, lock nuts for flanges and pressure vessels, subsea connector pins
Subsea Equipment
ROV tooling shafts, subsea tree stems, hydraulic coupling bodies, stab-plate guide pins
Refinery & Petrochemical
Process valve internals, thermowell stems, catalyst reactor internals, heat exchanger tie-rods
SHUNFU METAL verifies the mechanical properties of each production heat per ASTM A564 and AMS 5659, including transverse tensile and Charpy V-notch impact testing at sub-ambient temperatures when specified for Arctic or subsea deployments. Certificate traceability is maintained through the ISO 9001 / API Q1 digital quality dossier accompanying every shipment.
15-5PH Bar Stock Availability
SHUNFU METAL inventories and supplies 15-5PH (AMS 5659 / ASTM A564 XM-12) in solution-treated Condition A—the soft, machinable state that permits customer-side finish machining followed by a single-step aging treatment to final strength. All bar and forging stock is sourced from ISO 9001 and API Q1 certified mills and verified by in-house optical emission spectrometry against the heat certificate prior to shipment.
Hot-Rolled Round
Diameter 10 mm – 200 mm
Length 3,000 – 6,000 mm
Surface: black / peeled / ground finish on request
Hot-Rolled Flat
Thickness 10 mm – 120 mm
Width 40 mm – 600 mm
Length 2,000 – 6,000 mm
Forged Round
Diameter 150 mm – 600 mm
Length 2,000 – 8,000 mm
Rough-machined or as-forged condition
Forged Flat / Block
Thickness 80 mm – 400 mm
Width 150 mm – 1,000 mm
Custom step-forged or ring-rolled profiles available
SHUNFU METAL offers H900 through H1150 pre-aged condition upon request. For large-section forgings, double-vacuum-melted (VAR/ESR) stock is available to guarantee ferrite-free microstructure and maximum transverse toughness—verified by ultrasonic inspection per ASTM A388 and macro-etch evaluation per ASTM A604.
Chemical Composition of 15-5PH / S15500 (AMS 5659)
The precipitation-hardening response of 15-5PH is governed by its tightly controlled copper (Cu) and niobium+columbium (Nb+Ta) additions. During aging at 480–620°C, nanoscale Cu-rich clusters precipitate coherently on the martensitic matrix, producing up to 1,310 MPa UTS without the volume change and distortion typical of martensitic quench-hardening. The following composition is per AMS 5659 / ASTM A564 Type XM-12, verified by SHUNFU METAL on every incoming heat:
| Element | C | Mn | Si | Cr | Ni | Cu | Nb+Ta | Mo | P | S | Fe |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Min (%) | — | — | — | 14.00 | 3.50 | 2.50 | 0.15 | — | — | — | Bal. |
| Max (%) | 0.07 | 1.00 | 1.00 | 15.50 | 5.50 | 4.50 | 0.45 | 0.50 | 0.040 | 0.030 | Bal. |
The absence of intentional delta ferrite in 15-5PH—achieved through a balanced Creq/Nieq ratio—is the defining metallurgical distinction from 17-4PH. SHUNFU METAL validates this through quantitative metallography (ASTM E562) on every heat, ensuring the ferrite number is consistently below 1 FN, which directly translates into the superior transverse impact performance demanded by NACE MR0175 sour-service and subsea applications.
Mechanical Properties of 15-5PH (AMS 5659, Condition H900–H1150)
The mechanical properties shown below are the minimum guaranteed values per AMS 5659 for solution-treated and aged bar, tested in the longitudinal direction. Aging temperature is the single process lever: lower temperatures maximize strength, while higher temperatures prioritize toughness and stress-corrosion-cracking resistance. SHUNFU METAL supplies material aged to any of these conditions and provides the corresponding tensile and hardness certification from an ISO/IEC 17025 accredited laboratory.
| Condition | Aging Temp (°C) | Tensile Strength (MPa) | Yield Strength 0.2% (MPa) | Elongation A (%) | Reduction of Area Z (%) | Hardness (HRC) |
|---|---|---|---|---|---|---|
| Sol. Annealed (A) | 1038±15 °C / AC | — | — | — | — | 33 max |
| H900 | 482 | 1,310 | 1,172 | 10 | 35 | 40–47 |
| H925 | 496 | 1,172 | 1,069 | 10 | 38 | 38–45 |
| H1025 | 552 | 1,069 | 1,000 | 12 | 45 | 35–42 |
| H1075 | 580 | 1,000 | 862 | 13 | 45 | 32–38 |
| H1100 | 593 | 965 | 793 | 14 | 45 | 31–38 |
| H1150 | 621 | 931 | 724 | 16 | 50 | 28–37 |
For sour-service applications governed by NACE MR0175/ISO 15156, 15-5PH in the H1150 double-aged condition (H1150D) is the industry-recognized choice, offering maximum resistance to sulfide stress cracking at hardness levels not exceeding HRC 33. SHUNFU METAL can supply 15-5PH with Charpy V-notch impact testing at −46°C and −60°C for Arctic and cryogenic wellhead specifications.