Comparison of MP35N and Alloy UNS N07718

MP35N (UNS R30035/ ATI 35N) and UNS N07718 (Alloy 718) are often viewed as competing alloys, although the reality is that choosing which alloy to use is not simple. Each has specific properties that make it ideal for specific applications.

First, it is important to understand what you are comparing. Both UNS R30035 and UNS N07718 have “Oil and Gas” (known as “NACE” and API 6A 718, respectively) and “Aerospace” (known by their AMS designations – AMS5844 and AMS5845 for UNS R30035, and AMS5662 and AMS5663 for UNS N07718) variants. Each variant has different mechanical properties (the NACE variants of UNS R30035 come in a variety of cold working/aging temperature combinations depending on the used).

MP35N

MP35N is a nickel-cobalt alloy containing 33-37% nickel, 19-21% chromium, and 9-10.5% molybdenum, with small additions of titanium and iron (up to 1% each), carbon, manganese, silicon, phosphorus, and sulfur (less than 0.15% each). Cobalt is the balancing element (about 33%). It is known for its high tensile strength and ductility, making it a popular choice for oil and gas, aerospace and automotive fastener and nozzle/pin projects, as well as medical and dental equipment. However, chemistry and manufacturing also emphasize one of the most important properties of this alloy: corrosion resistance. UNS R30035's ability to resist corrosion from sources such as hydrogen sulfide or salt water means it is widely used in valve and pump applications, as well as marine projects.

UNS N07718 UNS N07718/Alloy 718 is a nickel-chromium alloy with small amounts of iron, niobium, and molybdenum. In recent years, this alloy has been widely used in the oil and gas industry, especially in surface and downhole applications. It is strong, easily welded, and corrosion resistant—not as good as UNS R30035, but still impressive. It is particularly durable at high temperatures, with the ability to withstand creep rupture even at temperatures up to 700°C. As a result, Alloy 718 is also frequently used in applications where heat resistance is critical, including aerospace, nuclear energy, rockets, and turbines.

Comparison of Advantages:

Alloy 718 and UNS R30035 both have high tensile strength and ductility in a variety of different environments. However, MP35N definitely outperforms Alloy 718 in tensile strength across all variants, with yield strength values of 175-260 ksi, while Alloy 718 has an optimal yield strength value of 130-150 ksi. Alloy 718 also suffers a significant loss of ductility at high yield strengths. For applications that require very high tensile strength, MP35N has the advantage. Both alloys also perform very well in specific environmental settings. The recommended temperature range for Alloy 718 is between -200°C and 550°C. In comparison, UNS R30035 has a temperature range of -200°C to 315°C. However, these operating temperatures need to be modified depending on the operating environment: In environments where the product may be exposed to salt water or other corrosive substances, the higher corrosion resistance of UNS R30035 makes it a superior product.