Project Description

Monel K-500 / UNS N05500 is a precipitation-hardenable nickel-copper alloy that retains the broad corrosion resistance of Monel 400 while delivering roughly three times the yield strength through the addition of aluminium and titanium. Age-hardening transforms the alloy’s microstructure by precipitating fine Ni₃(Al,Ti) particles, raising tensile strength to as high as 190 ksi (1,310 MPa) — levels that place it squarely in the high-strength structural category for downhole and offshore hardware. SHUNFU METAL supplies Monel K-500 round bar and forged bar produced from VIM + VAR remelt heats to ASTM B865 and AMS 4676, with full EN 10204 3.1 mill test certification.

Monel K-500 — Overview

Unlike Monel 400 — which can only be strengthened by cold working — Monel K-500 achieves high strength through age hardening at 593 °C (1,100 °F). This process precipitates coherent Ni₃(Al,Ti) intermetallics in the face-centred cubic nickel-copper matrix, producing hardness levels that approach the NACE MR-0175 limit without sacrificing the alloy’s inherent corrosion resistance in seawater, H₂S-bearing brines, and HF-acid environments.

Monel K-500 is essentially non-magnetic at room temperature (relative permeability μ < 1.003), which is a critical requirement for directional drilling tools where magnetic interference from the drill collar would compromise measurement-while-drilling (MWD) accuracy. The alloy also retains excellent low-temperature toughness, making it suitable for cryogenic LNG transfer hardware and Arctic subsea equipment.

At SHUNFU METAL, K-500 bar is forged from VIM+VAR remelt ingots to ensure a clean, homogeneous microstructure free of segregation. After forging, bars are solution-annealed at 980 °C and then age-hardened at 593 °C for 16 hours before a controlled air cool — all tracked by calibrated furnace data loggers. Optical emission spectrometry (OES) chemistry verification and Rockwell hardness surveys are performed on every batch, with results documented on the EN 10204 3.1 MTC.

Monel K-500 N05500 round bar age-hardened
Monel K-500 / N05500 Round Bar

Monel K-500 Equivalent Grades & Standards

Standard Body Designation Scope / Form
UNS (USA) N05500 All product forms
ASTM / ASME (USA) ASTM B865 / ASME SB-865 (bar & forging) Round bar, flat bar, forging stock
AMS (USA) AMS 4676 (bar & forging); formerly QQ-N-286 Aerospace & structural bar/forging
DIN / W.Nr. (Germany) 2.4375 (NiCu30Al); DIN 17743, DIN 17752–17754 Rod, bar, forgings
EN / ISO NW5500 (ISO); NiCu30Al (EN designation) International equivalent
BS (UK) NA18; BS 3072–3076 Sheet, strip, bar, tube, wire
JIS (Japan) NW5500 Bar, plate
GOST (Russia) МНАЖМц 28-2.5-1.5-0.5 (nearest equivalent) Nearest Russian equivalent
API API 5CRA (CRA Group 4 — non-magnetic drill collar) Downhole bar/collar stock
NACE / ISO 15156 MR-0175 / ISO 15156-3 Sour-service qualification (hardness ≤35 HRC)

Oil & Gas Applications — Monel K-500 Components

Non-Magnetic Drill Collars
The primary application for K-500 bar: age-hardened drill-collar bodies for MWD/LWD tools in directional drilling, where magnetic permeability must be <1.01.
Pump Shafts & Impellers
High-strength aged bar machined to close tolerances for centrifugal pump shafts and impellers in seawater injection, produced water, and subsea boosting systems.
Valve Stems & Actuator Shafts
Aged K-500 stems for subsea gate and ball valves handling sour gas or produced brine; NACE MR-0175 hardness limit ≤35 HRC is routinely achieved in the annealed-and-aged condition.
Wellhead Hanger Mandrels
Forged K-500 mandrels and locking ring components in wellheads and X-mas tree assemblies where high load-bearing capacity and corrosion resistance in H₂S/CO₂ brines are required.
Structural Bolting & Fasteners
Aged K-500 stud bolts and hex nuts for flanged subsea equipment and offshore structures, providing high preload capability while resisting galvanic attack in seawater.
Propeller Shafts
Marine propulsion shafts for drillships and FPSOs where K-500’s combination of high fatigue strength and seawater corrosion resistance eliminates the need for shaft-sleeve liners.
Instrumentation & Control Components
Precision machined sensor housings, gauge bodies, and flow controller shafts for offshore and subsea production instrumentation in corrosive process streams.
HF Alkylation Hardware
Reactor internals, settler parts, and pump impellers in hydrofluoric acid alkylation units, where K-500’s higher strength vs Monel 400 extends service life under combined mechanical and chemical loading.
Subsea Umbilical Connectors
High-strength connector bodies and locking pins for chemical injection and hydraulic control umbilicals, where load-bearing capacity must be maintained at depth under significant bolt preload.

Supply Forms & Size Range — Monel K-500 Bar

SHUNFU METAL’s K-500 bar is melted from VIM+VAR heats, hot-forged or rolled, then solution-annealed and age-hardened in controlled-atmosphere furnaces. Age-hardening cycles are documented per heat with calibrated furnace recorder charts included in the material dossier. Final bar is OES-verified, hardness-surveyed, and ultrasonically tested (UT) for sizes above Ø25 mm per ASTM E428.

Product Form Standard Size Range Condition
Hot-Rolled Round Bar ASTM B865 / AMS 4676 Ø 12 – 250 mm Hot-finished, annealed & aged
Cold-Drawn Round Bar ASTM B865 Ø 3 – 80 mm Cold-drawn, annealed & aged
Forged Round Bar ASTM B865 / AMS 4676 Ø 80 – 650 mm Forged, annealed & aged
Hot-Rolled Flat Bar ASTM B865 T 6–80 mm × W 20–300 mm Annealed & aged
Forged Flat / Block ASTM B865 / AMS 4676 T 20–300 mm × W 50–600 mm Forged, annealed & aged
Hexagon Bar ASTM B865 A/F 8 – 100 mm Cold-drawn / Annealed & aged

Standard bar lengths: 1,000–6,000 mm; cut-to-length and precision machined blanks available. Custom forgings (discs, rings, collar blanks) accepted to customer drawing. NACE MR-0175, API 5CRA, and DNV material certification available on request alongside EN 10204 3.1 MTC.

Chemical Composition — Monel K-500 (ASTM B865 / UNS N05500)

Element Min % Max % Role
Ni + Co 63.0 — Base element; corrosion resistance matrix
Cu 27.0 33.0 HF acid and seawater corrosion resistance
Al 2.30 3.15 Precipitation hardening — forms Ni₃(Al,Ti) phase
Ti 0.35 0.85 Co-precipitant; stabilises hardening phase
Fe — 2.0 Residual; kept low to maintain low permeability
Mn — 1.5 Deoxidiser; hot workability
C — 0.25 Kept low; carbides can impair ductility
Si — 0.50 Deoxidiser; minor hardener
S — 0.010 Tightly controlled for hot-ductility and grain-boundary integrity

Source: Special Metals Monel® K-500 data bulletin / ASTM B865. SHUNFU METAL performs OES verification on every heat at incoming inspection; Al and Ti are individually reported on the EN 10204 3.1 MTC — these are the hardening elements and must be within specification to guarantee the correct age-hardening response.

Mechanical Properties — Monel K-500 Bar (ASTM B865 / AMS 4676)

Condition UTS ksi (MPa) 0.2% YS ksi (MPa) Elongation % Hardness
Hot-Finish, Annealed 90–110 (621–758) 40–60 (276–414) 45–25 75–90 HRB
Hot-Finish, Annealed & Aged 130–165 (896–1,138) 85–120 (586–827) 35–20 24–35 HRC
Hot-Finish, Aged (no prior anneal) 140–190 (965–1,310) 100–150 (690–1,034) 30–20 27–38 HRC
Cold-Drawn, Annealed & Aged 130–190 (896–1,310) 85–120 (586–827) 30–20 24–35 HRC
Cold-Drawn, Aged (maximum strength) 135–185 (931–1,276) 95–160 (655–1,103) 30–15 25–41 HRC

Age hardening: typically 593 °C (1,100 °F) / 16 h / controlled air cool. Solution annealing (when specified): 980 °C (1,800 °F) / water quench. For NACE MR-0175 sour-service compliance, the annealed-and-aged condition (24–35 HRC) is normally specified, keeping hardness at or below the 35 HRC limit. SHUNFU METAL documents furnace time-temperature charts for each aging run and includes hardness data — measured at both ends and the mid-length of each bar — on the EN 10204 3.1 MTC.