Monel 400 and Monel K500 are both Monel alloys. What is the difference?
Monel 400 Description
Monel 400 alloy is a kind of alloy that can be used in seawater, chemical solvents, ammonia sulfur chloride, hydrogen chloride, various acidic media such as sulfuric acid, hydrofluoric acid, hydrochloric acid, phosphoric acid, organic acids , a nickel-based alloy material with good corrosion resistance in alkaline media, salt and molten salt. Monel 400 alloy also has good mechanical properties, a wide range of use temperatures from low to high temperatures, good welding properties and medium and high strength. Monel 400 is mainly used in chemical and petrochemical industries, as well as marine development and other fields. It can be used to manufacture various heat exchange equipment, boiler feed water heaters, petroleum and chemical pipelines, containers, towers, tanks, valves, pumps, reactors, shafts, etc. The alloy can be machined using the same methods as traditional iron-based materials. Use water coolant when adding high speed machines. The material shrinks during processing, so attention should be paid to the processing shrinkage allowance to ensure dimensional accuracy. Monel 400 has good welding performance and can use TIG and MIG methods. It can use Monel body or EniCu-7 wire and electrode; or manual arc welding and submerged arc welding; it can be welded with carbon steel and low alloy steel.
Monel K500 Description
Monel K500 alloy is a new alloy with excellent corrosion resistance and higher strength and hardness than Monel 400. This is due to the addition of Al, Ti and other elements to the alloy, and after a certain heat treatment, there are dispersed intermetallic compounds on the matrix. The organizational structure is a single-phase austenite structure and is precipitated by dispersed Ni3 (Al, Ti) precipitation phases. Monel K500 has approximately three times the yield strength and twice the tensile strength of Monel 400, and higher mechanical properties can be obtained through cold working or age hardening. Monel K500 alloy has the same corrosion resistance as Monel 400 alloy. Monel K500 alloy is mainly used for pump shafts and impellers, conveyor scrapers, oil well drill rings, elastic parts, valve gaskets, etc. Others can also manufacture various heat exchange equipment, boiler feed water heaters, petroleum and chemical pipelines, containers, towers, tanks, valves, pumps, reactors, shafts, etc. Due to its low corrosion rate in flowing seawater and the high strength of this alloy, Monel K500 is suitable for manufacturing centrifugal pump shafts that are resistant to seawater corrosion. Suitable for both static and flowing sea water.
Difference between Monel 400 and Monel K500
Monel400 is composed almost entirely of nickel (>63%) and copper (28-34%), with only smaller amounts of iron, manganese and other trace elements. Nickel and copper are soluble in each other, so the microstructure consists of a single phase. It can be strengthened by cold working but not by heat treatment. Alloy 400 has relatively high strength compared to other copper alloys, and its impact properties remain at levels below zero to 480°C. However, the strength level of Monel400 limits its use in more structural applications. Monel K500 was developed to overcome this limitation. Its composition is the same as Monel400, but aluminum and titanium are added in small amounts (3-4% total). Aluminum and titanium combine to form microscopic precipitates that can be controlled by heat treatment. After forging or rolling, round steel undergoes an aging heat treatment, keeping it at high temperature for several hours and then slowly cooling in the air. This process ensures that as much aluminum and titanium as possible can be extracted from the solution and form a fine, widely dispersed network. These precipitates produced significant improvements in mechanical properties - a 4-fold increase in yield strength and a 2-fold increase in tensile strength. The increased strength of Monel K500 means it can be used effectively on more challenging components such as marine shafts, valve stems, fasteners, mixer and stirrer shafts as well as doctor blades, drill collars and heat exchanger components. Since the composition of Monel K500 is virtually identical to that of Monel 400, the basic chemical and corrosion resistance remains the same. There is an argument that Alloy K500 may be more susceptible to stress corrosion cracking in limited circumstances, but this is most likely due to its use in higher stress applications (because of its higher strength).
Since the specifications of Monel K500 have no obvious shortcomings compared to Monel400, and with the significant improvement in strength, a large number of new application fields have been opened up, so the market usage of Monel K500 materials is more abundant.
