When in the age-hardened condition, Monel K-500 has a greater tendency toward  stress-corrosion cracking in some environments than Monel 400. Alloy K-500 has  approximately three times the yield strength and double the tensile strength  when compared with alloy 400. Plus, it can be further strengthened by cold  working prior to precipitation hardening. The strength of this nickel steel  alloy is maintained to 1200° F but stays ductile and tough down to temperatures  of 400° F. Its melting range is 2400-2460° F.

This nickel alloy is spark resistant and non-magnetic to -200° F. However, it  is possible to develop a magnetic layer on the surface of the material during  processing. Aluminum and copper may be selectively oxidized during heating,  leaving a magnetic nickel rich film on the outside. Pickling or bright dipping  in acid can remove this magnetic film and restore the non-magnetic  properties.

Corrosion Resistant Monel K-500

The corrosion resistance of alloy K-500 is substantially equivalent to that  of alloy 400 except that when in the age-hardened condition, nickel alloy K-500  has a greater tendency toward stress-corrosion cracking in some environments.  Monel K-500 has been found to be resistant to a sour-gas environment. The  combination of very low corrosion rates in high-velocity sear water and high  strength make alloy K-500 particularly suitable for shafts of centrifugal pumps  in marine service. In stagnant or slow-moving sea water, fouling may occur  followed by pitting but this pitting slows down after a fairly rapid initial  attack.

What are the characteristics of Monel K500?

· Corrosion resistance in an extensive range of marine and chemical  environments. From pure water to non-oxidizing mineral acids, salts and  alkalis.

· Excellent resistance to high velocity sea water

· Resistant to a sour-gas environment

· Excellent mechanical properties from sub-zero temperatures up to about  480C

· Non-magnetic alloy

Chemical Composition, %

In what applications is Monel K-500 used?

· Sour-gas service applications

· Oil and gas production safety lifts and valves

· Oil-well tools and instruments like drill collars

· Oil well industry

· Doctor blades and scrapers

· Chains, cables, springs, valve trim, fasteners for marine service

· Pump shafts and impellers in marine service

Fabrication with Monel K-500

Monel K-500 is readily fabricated by standard commercial procedures.

Welding alloy K-500 is best accomplished by the gas-tungsten-arc welding  process. It is recommended that Monel K-500 be annealed when it is welded and  that any weldments be stress relieved prior to aging.

Heavy machining of this alloy is best accomplished when the material is in  the annealed condition or hot-worked and quenched condition. Age-hardened  material however can be finish-machined to close tolerances and fine finishes.  Therefore, the recommended practice is to machine slightly oversize, age-harden,  then finish to size. During aging, a slight permanent contraction takes place,  but little warpage occurs because of the low temperatures and slow cooling rates  involved.

For more information on fabrication and machining, click here.

Specifications

Mechanical Properties

Typical Room Temperature Tensile Properties of Annealed Material