Monel K-500 (UNS N05500) Age-Hardened Bar, Forgings and Fittings

Monel K-500 is Monel 400 with aluminium and titanium added to allow precipitation hardening. The result keeps essentially all of the 400 alloy’s resistance to seawater and hydrofluoric acid while roughly doubling the strength and substantially increasing hardness and wear resistance. That combination is why K-500 appears where 400 is simply too soft — pump shafts, valve stems, springs, fasteners and high-stress marine hardware.

IMPORTANT — material specification note, stated plainly

There is an honest limitation here, and we would rather flag it than paper over it. Our ASME Section II offline library does not contain a dedicated K-500 plate, sheet, bar or forging specification comparable to SB-564 or SB-333 for other nickel alloys. The K-500 composition limits reproduced below are taken from ASME SB-956 (welded copper and copper-alloy condenser and heat exchanger tubes with integral fins), which lists Alloy 500 among the alloys it references. Mechanical property values, heat-treatment temperatures and available product forms must be confirmed with our factory technical department before you commit to a specification. Treat the table as a reference, not as a purchasing basis.

Composition, as listed in ASME SB-956 (% by weight)

The aluminium and titanium ranges are the distinguishing feature; a 400-alloy certificate will show no aluminium at all.

Product forms we supply

– Round bar and rod, hot-rolled or forged, solution annealed or aged condition

– Forging stock — billets, discs and stepped blanks, machined to your drawing

– Fittings — flanges and machined components, in solution annealed or aged condition

– Wire and strip on request

Nickel-copper pipe and fittings in 400 grade are covered separately on this site; this page is the K-500 grade line.

Condition and hardness

K-500 is supplied either solution annealed (soft, machinable, then aged by the customer) or fully aged. The aged condition provides the higher strength and hardness that define the alloy. Aged bar is markedly harder to machine than annealed bar and is normally finished by grinding rather than turning — worth raising early if the design depends on a specific machining allowance. Age-hardening temperature and time are confirmed per order with our technical department.

Applications

Seawater systems and marine hardware, hydrofluoric acid alkylation service, sour gas and oil-and-gas components, pump shafts and impellers, valve stems and trim, springs and high-strength fasteners, desalination equipment, and chemical process components requiring seawater resistance with added wear resistance.

Inspection and certification

EN 10204 3.1 standard, 3.2 on request. PMI to confirm aluminium and titanium, tensile testing, hardness testing and, where the end use requires it, intergranular corrosion testing.

Ordering information

Give grade (K-500 / N05500), condition (annealed or aged), product form, size or diameter and tolerance, quantity, and certification level. Because K-500 property data is application-sensitive, tell us the service and temperature when you enquire — we will return confirmed mechanical properties along with the quotation rather than after you have ordered.

Related ranges: dimensional and standards background for this product is set out in our nickel alloy fitting range. See also our Round Bars. Pressure class and facing data for every range is kept in one place.