Project Description
Carpenter 465, also designated as UNS S46500, is a premium double-vacuum-melted martensitic age-hardenable stainless steel engineered by Carpenter Technology Corporation to deliver the highest strength available in any precipitation-hardening stainless long product. Capable of ultimate tensile strength exceeding 1790 MPa (260 ksi) in the H900 condition while retaining corrosion resistance approaching Type 304 stainless, the alloy was designed to displace cadmium-plated and chromium-plated alloy steels in critical aerospace, oil & gas, marine, and medical applications. The lean martensitic matrix—nominally Fe-12Cr-11Ni-1.7Ti-1Mo—is processed through a VIM + VAR double-melt route, ensuring exceptionally low inclusion content and superior transverse mechanical properties. Covered under AMS 5936, ASTM A564, ASTM A693, ASTM F899, and MMPDS-01, Carpenter 465 has become the reference material for ultra-high-strength corrosion-resistant fasteners, subsea structural bolting, high-pressure valve stems, downhole drive shafts, landing-gear components, and orthopedic surgical instruments where the combination of extreme strength, fracture toughness (~88–99 MPa√m), and resistance to chloride SCC is mission-critical.
Carpenter 465 / S46500 — Overview
Carpenter 465 (UNS S46500) represents the pinnacle of the precipitation-hardening stainless portfolio: a patented martensitic alloy that in the H900 peak-aged condition reaches approximately 1790 MPa (260 ksi) ultimate tensile strength, making it roughly 20% stronger than Carpenter Custom 455 and 40% stronger than 17-4PH at their peak conditions. The alloy achieves this through a tightly balanced Ti-Mo-Cr-Ni chemistry that promotes a high-volume fraction of fine intermetallic precipitates—primarily Ni3Ti—during aging, while the ultra-low carbon content (≤0.02%) suppresses chromium carbide formation, preserving intergranular corrosion resistance and weldability. A defining practical advantage is the elimination of protective electroplating: unlike alloy steels such as 4340 and 300M that require cadmium or chromium coatings, Carpenter 465 is inherently corrosion-resistant, removing the risk of plating delamination, hydrogen embrittlement from plating baths, and the lifecycle cost of periodic coating inspection and rework. SHUNFU METAL supplies Carpenter 465 bar stock under a fully integrated ISO 9001 and API Q1 quality management system: each heat lot undergoes optical emission spectrometry for full chemistry verification, ultrasonic inspection per AMS-STD-2154 for internal soundness, macro-etch evaluation per AMS 2300 to confirm freedom from harmful segregation, and full mechanical testing at the specified aging condition against AMS 5936 minimum requirements. VAR-remelted stock is standard to guarantee the cleanness and transverse toughness the design allowables demand.
Equivalent Standards of Carpenter 465 / S46500
| Standard | Specification | Grade |
|---|---|---|
| AMS | 5936 | Carpenter 465 |
| ASTM | A564 / A693 | S46500 |
| ASTM | F899 | S46500 (Surgical) |
| UNS | — | S46500 |
| MMPDS | MMPDS-01 | S46500 |
| EN | 10088-3 | 1.4614 |
| DIN | — | X11CrNiMoTi11-11-1 |
| GB | GB/T 20878 | 02Cr11Ni11MoTi |
| SAE | BMS 7-364 / BSS 7025 | Carpenter 465 |
Oil & Gas Applications
Subsea & Deepwater Valves
High-pressure gate and ball valve stems, seats, and trim for subsea manifolds and deepwater Xmas tree systems; Carpenter 465 eliminates the need for protective coatings in chloride-rich seawater at depths exceeding 3000 m.
Downhole Drive Shafts
Rotary steerable system shafts, MWD/LWD mandrels, and mud motor flex shafts requiring 260-ksi tensile capacity with resistance to H2S and chloride-rich drilling fluids.
High-Strength Fasteners
Subsea structural bolting, flange studs, and connector tension bolts per ASTM F899; 260 ksi UTS enables significant weight reduction versus coated alloy steel fasteners in topside and subsea flanged connections.
Pump & Compressor Shafts
High-speed centrifugal pump shafts, reciprocating compressor piston rods, and injection pump plungers exposed to produced water, CO2, and H2S in gas lift and enhanced oil recovery operations.
Wellhead & Xmas Tree Components
Gate and seat inserts, choke stems, hanger lock rings, and actuator stems where H1000-aged fracture toughness exceeds 99 MPa√m for high-integrity pressure containment.
BOP & Pressure Control
Blowout preventer hydraulic actuator rods, shear-blade carrier pins, and ram shaft components; the H950 condition provides the strength-toughness balance required for emergency well-control equipment.
Completion & Intervention Tools
Perforating gun body mandrels, setting-tool power pistons, wireline and slickline stems; the H900 condition delivers maximum strength for compact tool architecture in slimhole completions.
Marine & Propulsion Shafts
FPSO and offshore platform propulsion shafts, thruster drive shafts, and seawater lift pump shafts; the alloy’s inherent corrosion resistance eliminates chronic coating failure in the splash zone.
Refinery & Petrochemical
Hydrocracker valve internals, reformer furnace fastener assemblies, and high-temperature pump components operating in hydrogen-rich environments up to 427°C (800°F) with SCC resistance superior to PH 13-8 Mo.
Bar Stock Availability
Hot Rolled Round Bar
Diameter: 10 mm – 200 mm
Length: 3000 – 6000 mm
Surface: black / peeled / rough-turned
Hot Rolled Flat Bar
Thickness: 6 mm – 120 mm
Width: 40 mm – 610 mm
Length: 3000 – 6000 mm
Forged Round Bar
Diameter: 100 mm – 600 mm
Length: 2000 – 8000 mm
Surface: rough-machined / turned
Forged Flat / Block
Thickness: 50 mm – 400 mm
Width: 100 mm – 1200 mm
Length: 1000 – 5000 mm
Bar stock is supplied in Solution Annealed (Condition A) per AMS 5936: heat to 982°C ± 8°C, hold 1 hour, then oil quench or rapid air cool. All material carries full mill test certification and is traceable to heat number. SHUNFU METAL also offers centerless-ground (h7/h8 tolerance) and polished finish options for precision applications, ESR- and VAR-remelted material for enhanced cleanness and transverse properties, and cut-to-length service from in-house inventory. Ultrasonic testing to AMS-STD-2154 Class AA is standard; Class AAA and custom scan plans are available on request.
Chemical Composition — AMS 5936
| Element | C | Mn | Si | P | S | Cr | Ni | Mo | Ti |
|---|---|---|---|---|---|---|---|---|---|
| Min (%) | — | — | — | — | — | 11.00 | 10.75 | 0.75 | 1.50 |
| Max (%) | 0.02 | 0.25 | 0.25 | 0.015 | 0.010 | 12.50 | 11.25 | 1.25 | 1.80 |
Composition per AMS 5936. Iron balance. Nitrogen limited to 0.01% max. The ultra-low carbon content (≤0.02%) suppresses M23C6 carbide precipitation at grain boundaries, preserving intergranular corrosion resistance in the aged condition. Titanium at 1.50–1.80% is the primary precipitation-hardening element, forming coherent nanoscale Ni3Ti phases during aging at 480–595°C. Molybdenum at 0.75–1.25% enhances pitting resistance in chloride-bearing environments. Chromium at 11.00–12.50% provides a stable passive film, yielding corrosion rates in salt-spray testing (ASTM B117) comparable to Type 304. SHUNFU METAL verifies each heat with optical emission spectrometry and reports the full element-by-element analysis on every certification document.
Mechanical Properties — AMS 5936 (Solution Annealed + Aged)
All values longitudinal, minimum per AMS 5936 for bar ≤ 305 mm (12 in). Solution anneal at 982°C ± 8°C, air cool or oil quench, refrigerate to −73°C for 8 hours within 24 hours of annealing, then age at indicated temperature for 4 hours, air cool. SHUNFU METAL performs tensile testing per ASTM E8 and hardness per ASTM E18 on each production lot; full certified reports accompany every shipment.
| Condition | Aging Temp | UTS (MPa) | YS 0.2% (MPa) | Elong. (%) | RA (%) | Hardness (HRC) |
|---|---|---|---|---|---|---|
| Solution Annealed (Cond. A) | — | 1000 (typ.) | 730 (typ.) | ≥ 6 (typ.) | — | ≤ 30 |
| H900 | 482 °C (900 °F) | 1790 (260 ksi) | 1724 (250 ksi) | ≥ 8 | ≥ 40 | 50 – 55 |
| H950 | 510 °C (950 °F) | ≥ 1655 (240 ksi) | ≥ 1515 (220 ksi) | ≥ 10 | ≥ 45 | 49 – 52 |
| H1000 | 538 °C (1000 °F) | ≥ 1515 (220 ksi) | ≥ 1380 (200 ksi) | ≥ 10 | ≥ 50 | 47 – 50 |
| H1050 | 566 °C (1050 °F) | ≥ 1448 (210 ksi) | ≥ 1344 (195 ksi) | ≥ 10 | ≥ 50 | 45 – 48 |
| H1100 | 593 °C (1100 °F) | ≥ 1310 (190 ksi) | ≥ 1069 (155 ksi) | ≥ 12 | ≥ 50 | 40 – 43 |
H950 and H1000 transverse properties also certified where specified. Fracture toughness (KIc) in H950 is approximately 88–99 MPa√m (80–90 ksi√in). Over-aging to H1000 and H1050 trades approximately 10–15% of tensile strength for substantially improved SCC resistance and toughness, making these conditions preferred for subsea bolting and wellhead pressure-boundary components. SHUNFU METAL’s in-house heat-treatment facility supports all standard aging conditions; custom time–temperature profiles can be qualified per customer specification.