Project Description
Carpenter 455, also designated as UNS S45500 and ASTM XM-16, is a martensitic age-hardenable stainless steel developed by Carpenter Technology Corporation. Engineered around a Cr-Ni-Cu-Ti-Nb precipitation system, the alloy is supplied in a soft, formable annealed condition and achieves ultra-high strength through a single-step low-temperature aging treatment at 480–566°C (900–1050°F)—with nearly zero dimensional change (−0.001 in/in), permitting close-tolerance finish machining prior to hardening. The Ti-Nb stabilized composition delivers yield strengths exceeding 1689 MPa in the H900 condition while maintaining corrosion resistance superior to Type 410 and approaching Type 430. Covered under AMS 5617, ASTM A564/A693/A705, and ASTM F899, the alloy is widely specified for aerospace fasteners, surgical instruments, high-pressure oil & gas valve components, downhole springs, subsea structural bolting, and turbomachinery shafts where the combination of extreme strength, dimensional precision, corrosion resistance, and fatigue performance is mission-critical.
Carpenter 455 / S45500 — Overview
Carpenter 455 (UNS S45500, XM-16) is a martensitic precipitation-hardening stainless steel whose defining advantage is the simplicity of its hardening response: a single-step aging cycle transforms the soft, easily machinable annealed structure into a state delivering approximately three times the yield strength of Type 304—without the distortion, scaling, or decarburisation associated with quench-and-temper steels. The low work-hardening rate in the annealed condition enables extensive cold forming, deep drawing, and cold heading, making the alloy exceptionally well-suited for high-volume fastener production and intricate machined parts. The titanium-niobium-copper precipitation sequence produces a fine dispersion of Ni3Ti and epsilon-Cu phases that push hardness to approximately 50 HRC while retaining useful ductility. SHUNFU METAL manufactures and distributes Carpenter 455 bar under a fully integrated ISO 9001 and API Q1 quality management system: every heat undergoes in-house optical emission spectrometry for full chemistry verification, ultrasonic testing per AMS-STD-2154 for internal soundness, and mechanical testing at each aging condition to guarantee conformance with AMS 5617, ASTM A564, and customer-specific requirements.
Equivalent Standards of Carpenter 455 / S45500
| Standard | Specification | Grade |
|---|---|---|
| ASTM | A564 / A693 / A705 | XM-16 |
| AMS | 5617 / 5860 | Carpenter 455 |
| UNS | — | S45500 |
| SAE | — | XM-16 |
| EN | 10088-3 | 1.4543 — X3CrNiCuTiNb12-9 |
| DIN | — | X12CrNiCuTi12-8-3 |
| GB | GB/T 20878 | S51290 (02Cr12Ni8Cu2Ti) |
| ASTM F899 | Surgical Instruments | XM-16 |
Carpenter 455 — Oil & Gas Applications
High-pressure gate, globe, and choke valve stems operating in corrosive well fluids; ball valve seats requiring both galling resistance and high hardness.
Coiled springs, Belleville washers, snap rings, and locking retainers in SSSV, packer, and sliding-sleeve assemblies.
Studs, bolts, socket-head cap screws, and tensioning studs for wellhead connectors, flange clamp assemblies, and manifold bolting to 170 ksi UTS.
Multi-stage centrifugal pump shafts, progressing-cavity pump drives, and high-speed coupling hubs subjected to torsional fatigue and wear.
Subsea manifold flange studs, clamp-hub connectors, and structural tie-rod fasteners in deepwater tree and manifold systems, aged to H950/H1000.
Actuator stems, lock-down screws, seal retaining rings, and instrumentation bosses in HPHT wellhead and Xmas tree assemblies.
BOP ram shafts, bonnet studs, shear-blade actuators, and hydraulic control pins in blowout preventer stack and choke/kill manifold assemblies.
Compressor rotor shafts, turbine blade shroud rings, and high-speed spindle components where precipitation-hardened strength is retained up to~425°C.
High-temperature bolting for FCCU flanges, reformer tube-sheet fasteners, and corrosion-resistant springs in amine and sour-water service.
Bar Stock — Supply Range & Processing
Dia. 10mm–200mm
Length: 3m–9m
Surface: black/peeled/ground
Condition: Solution annealed
Thk 6mm–80mm
Width: 50mm–610mm
Length: 3m–6m
Condition: Solution annealed
Dia. 80mm–600mm
Length: up to 8m
Rough-machined or black
Condition: Solution annealed
Thk 30mm–400mm
Width: 100mm–1200mm
Rough-machined surfaces
Condition: Solution annealed
At SHUNFU METAL, Carpenter 455 bar production follows a tightly controlled route: EAF / AOD melting with optional VAR or ESR refining for applications requiring the highest micro-cleanliness and transverse properties. Solution treatment at 815–830°C (1500–1525°F) followed by air cooling delivers the fully annealed (Condition A) microstructure. Every bar is verified for conformance to AMS 5617 chemistry limits using in-house OES, and ultrasonic inspection per AMS-STD-2154 is applied to forged products above 100mm diameter. For oil & gas customers, additional sour-service qualification per NACE MR0175/ISO 15156 hardness limits, sulfide stress cracking testing per NACE TM0177 Method A, and certified Charpy V-notch impact testing at −46°C are routinely supplied through SHUNFU’s ISO 9001 and API Q1-certified quality framework.
Chemical Composition of Carpenter 455 / S45500 — AMS 5617
| Element | C | Mn | Si | P | S | Cr | Ni | Mo | Cu | Ti | Nb+Ta | Fe |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Min (wt%) | — | — | — | — | — | 11.00 | 7.50 | — | 1.50 | 0.80 | 0.10 | Bal |
| Max (wt%) | 0.05 | 0.50 | 0.50 | 0.040 | 0.030 | 12.50 | 9.50 | 0.50 | 2.50 | 1.40 | 0.50 |
The precipitation-hardening response of Carpenter 455 is driven by the Ti-Nb-Cu triad. During aging at 480–566°C, nanoscale intermetallic Ni3(Ti,Nb) and epsilon-Cu precipitates form coherently within the martensitic matrix, producing an exceptionally effective dislocation-pinning mechanism that drives yield strength above 1600 MPa. The ultra-low carbon ceiling (0.05% max) combined with titanium and niobium stabilization suppresses chromium-carbide precipitation at grain boundaries, ensuring resistance to intergranular corrosion in the aged condition and good as-welded integrity. SHUNFU METAL verifies the full 11-element analysis on every production heat using calibrated OES as part of the ISO 9001 / API Q1 release protocol.
Carpenter 455 — Mechanical Properties per AMS 5617
| Condition | Aging Temp | Tensile Strength (MPa) | 0.2% Yield Strength (MPa) | Elongation (%) | Reduction of Area (%) | Hardness (HRC) |
|---|---|---|---|---|---|---|
| Solution Annealed (A) | — | 965 | 793 | 14 | 60 | 31 |
| H900 | 480°C × 4h / AC | 1724 | 1689 | 10 | 45 | 49 |
| H950 | 510°C × 4h / AC | 1620 | 1551 | 12 | 50 | 48 |
| H1000 | 538°C × 4h / AC | 1448 | 1379 | 14 | 55 | 45 |
| H1050 | 566°C × 4h / AC | 1310 | 1207 | 15 | 55 | 40 |
Typical room-temperature tensile properties measured on 25.4mm (1-inch) bar section per AMS 5617. The H900 condition delivers peak strength (YS ≥1689 MPa) for high-load fasteners and tooling components; H950/H1000 offer the optimum strength-toughness balance for subsea bolting and sour-service valve stems; H1050 provides the highest ductility and toughness for large-section forgings requiring Charpy V-notch impact resistance. Elevated-temperature tensile testing (H950/H1000 material) confirms retained yield strength above 1100 MPa at 316°C and above 750 MPa at 538°C. SHUNFU METAL performs certified tensile, hardness, and Charpy testing on every production lot aged to the customer-specified condition, fully documented under the ISO 9001 and API Q1 quality management system.