Monel K500 / UNS N05500 / W.Nr. 2.4375
Monel K-500
Monel K500 is a precipitation-hardenable nickel-copper alloy that boasts excellent corrosion resistance properties, which are even better than those of Monel 400. In addition, this alloy is distinguished by its greater strength and hardness, which is achieved by adding aluminum and titanium to the nickel-copper base and by employing thermal processing for precipitation hardening, also known as aging.
When Monel K500 is in the age-hardened condition, it has a higher susceptibility to stress-corrosion cracking in certain environments compared to Monel 400. However, Alloy K500 has roughly three times the yield strength and double the tensile strength of Alloy 400. Moreover, it can be further strengthened by cold working before precipitation hardening. The strength of Monel K500 is maintained up to 1200°F and remains ductile and tough even at temperatures as low as 400°F. Its melting range is 2400-2460°F.
Monel K500 is also spark-resistant and non-magnetic down to -200°F. However, during processing, it is possible to develop a magnetic layer on the surface of the material. This occurs when aluminum and copper selectively oxidize during heating, leaving a magnetic nickel-rich film on the outside. Fortunately, this magnetic film can be removed by pickling or bright dipping in acid, which will restore the non-magnetic properties of the alloy.
Due to its exceptional properties, Monel K500 is commonly used in various industrial applications, such as marine engineering, chemical processing, and oil and gas production. Its strength and resistance to corrosion make it an ideal material for valve stems, pump shafts, and fasteners. Monel K500 is also used in high-performance applications that require non-magnetic materials, such as instrumentation components, magnetic housings, and gyroscopes.
Industries and Applications
Monel K500, also known as Alloy K500, is a nickel-copper alloy that combines excellent corrosion resistance with enhanced strength and hardness. These properties make it a popular material in various industrial applications where durability and reliability are paramount. In this article, we’ll explore some of the industries and applications where Monel K500 is commonly used.
Marine Engineering: Monel K500 is a popular choice in marine engineering due to its excellent corrosion resistance properties, even in seawater environments. It is often used to make valve stems, pump shafts, and other components that are exposed to harsh seawater conditions. Additionally, Monel K500’s non-magnetic properties make it ideal for use in magnetic housings, which are used in compasses and other navigation systems.
Chemical Processing: In the chemical processing industry, Monel K500 is used to make equipment such as heat exchangers, evaporators, and pressure vessels. The alloy’s excellent resistance to corrosion in acidic and alkaline environments makes it a reliable choice for use in these applications. Additionally, Monel K500’s high strength and toughness make it ideal for use in components that are subject to high stress and pressure.
Oil and Gas Production: Monel K500 is commonly used in the oil and gas production industry to make tubing, valves, and other components that are used in corrosive environments. The alloy’s excellent resistance to corrosion and high strength make it ideal for use in these applications. Additionally, Monel K500’s non-magnetic properties make it ideal for use in instrumentation components that require non-magnetic materials.
Aerospace: Monel K500 is used in the aerospace industry to make components that require high strength and toughness, such as fasteners and springs. Additionally, the alloy’s resistance to corrosion makes it a reliable choice for use in aerospace applications, where components are exposed to harsh environmental conditions.
Medical Devices: Monel K500 is used in medical devices such as pacemaker components, due to its non-magnetic properties and excellent biocompatibility. The alloy’s resistance to corrosion and high strength make it a reliable choice for use in these applications
Resistance to Corrosion
One of the key benefits of Monel 400 is its resistance to corrosion. This alloy is highly resistant to corrosion in a variety of environments, including seawater, acids, and alkalis. This makes it an ideal choice for applications in the marine industry, where it is used for everything from propeller shafts to seawater valves.
Another advantage of Monel 400 is its resistance to stress corrosion cracking. This is a type of corrosion that occurs when a material is exposed to a combination of tensile stress and a corrosive environment. Monel 400 is highly resistant to this type of corrosion, making it a popular choice for applications where high-stress levels are present.
In addition to its resistance to corrosion, Monel 400 also offers excellent resistance to a wide range of other forms of chemical attack. This includes resistance to hydrofluoric acid, sulfuric acid, and other highly corrosive substances. As a result, Monel 400 is often used in the chemical processing industry, where it is employed for everything from heat exchangers to process vessels.
Fabrication and Heat Treatment
Monel K500 is a ductile material that can be easily fabricated using common techniques such as welding, brazing, and soldering. However, care must be taken during the fabrication process to avoid intergranular corrosion, which can occur if the alloy is exposed to temperatures between 800°F and 1600°F. To prevent intergranular corrosion, it is recommended that Monel K500 be annealed after welding, brazing, or soldering.
Monel K500 can be formed using cold working techniques, such as rolling, bending, and stamping. However, care must be taken to avoid cracking during these processes. To minimize the risk of cracking, it is recommended that Monel K500 be annealed before cold working and that it be cold worked in stages, with intermediate annealing steps.
Monel K500 can be heat treated to achieve precipitation hardening, which increases the alloy’s strength and hardness. The heat treatment process involves a solution annealing step, followed by aging at a specific temperature for a specified amount of time.
During solution annealing, Monel K500 is heated to a temperature between 1700°F and 1900°F, held at that temperature for a specific amount of time, and then cooled at a controlled rate. This process helps to dissolve any precipitates that may have formed during cold working or other fabrication processes.
After solution annealing, Monel K500 is aged at a temperature between 900°F and 1050°F for a specified amount of time. This process helps to form fine precipitates, which increase the alloy’s strength and hardness. The aging process can be performed at different temperatures and for different durations to achieve specific properties in the alloy.
Monel K500 – Applicable Specifications
| Form | ASTM | ASME | Other |
|---|---|---|---|
Monel K500 Bar |
B865-04 | SB865-04 | – |
Monel K500 Plate |
B865-04 | SB865-04 | – |
Monel K500 Sheet |
B865-04 | SB865-04 | – |
Monel K500 Pipe |
B165-05 | SB165-05 | – |
Monel K500 Tube |
B165-05 | SB165-05 | – |
Monel K500 Fittings |
B366-04 | SB366-04 | – |
Monel K500 Forgings |
B564-04 | SB564-04 | – |
Monel K500 Welding Wire |
B164-03 | SB164-03 | AWS A5.14 |
Common Trade Names
Monel K500 is known by various trade names, including Nicorros Alkon, Alumel 400, and Monel Alloy K-500. These names are used interchangeably to refer to this high-strength nickel-copper alloy.
Key Properties
(in annealed condition)
| Property | Alloy K500 |
|---|---|
| Tensile Strength | 110 ksi (760 MPa) |
| Yield Strength | 50 ksi (345 MPa) |
| Elongation | 20% (in 2 inches) |
| Hardness (Rockwell C) | 32 – 43 |
Chemical Composition (%)
| Element | Alloy K500 |
|---|---|
| Nickel (Ni) | 63.0 – 70.0 |
| Copper (Cu) | 27.0 – 33.0 |
| Aluminum (Al) | 2.30 – 3.15 |
| Titanium (Ti) | 0.35 – 0.85 |
| Iron (Fe) | 0.50 max |
| Manganese (Mn) | 1.5 max |
| Carbon (C) | 0.25 max |
| Silicon (Si) | 0.50 max |
| Sulfur (S) | 0.010 max |
| Phosphorus (P) | 0.015 max |
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