1.Chemical Composition
Both are nickel - copper alloys with nickel content of at least 63% and copper content in the range of 28.0 - 34.0%. The main difference is that Monel R405 has a sulfur content of 0.025 - 0.060%. This addition of sulfur forms sulfide inclusions, which is not a feature of Monel 400.
2.Machinability: Monel R405 is the free - machining version of Monel 400. The sulfide inclusions in Monel R405 act as chip breakers during machining. This makes Monel R405 much easier to machine than Monel 400, especially suitable for high - speed precision cutting operations such as turning, milling, and drilling, and is commonly used as automatic - screw - machine stock.
3.Mechanical Properties: The mechanical properties of the two are slightly different. The ultimate tensile strength of Monel 400 is 540 - 780 MPa, while that of Monel R405 is 480 - 620 MPa. The yield strength of Monel 400 is 210 - 590 MPa, and the yield strength of Monel R405 is 170 - 345 MPa, depending on the processing state. The elongation of Monel R405 is 20% - 35%, showing good toughness. The Brinell hardness of Monel R405 is 120 - 180 HB, which is suitable for occasions requiring wear resistance.
4.Corrosion Resistance
In general, the corrosion resistance of Monel 400 and Monel R405 is similar. Both are resistant to seawater, high - temperature steam, salt, and corrosive solutions. They have low corrosion rates in fast - flowing salt water or seawater and excellent resistance to stress - corrosion cracking in most freshwaters. However, neither can be used in oxidizing acids such as nitric acid and nitrous acid.
5.Application Fields
Monel 400 is widely used in general marine applications, chemical, and petroleum industries due to its balanced properties. Monel R405 is mainly used as automatic - screw - machine stock for manufacturing fasteners and other high - production - run items. It is also suitable for manufacturing precision parts such as valves due to its good machinability.
