Inconel 625 is a Nickel-Chromium-Molybdenum alloy with superb corrosion resistance in a large range of corrosive media, being especially resistant to pitting and crevice corrosion. It is a favorable choice for seawater applications. It has excellent mechanical properties at both extremely low and extremely high temperatures, exceptional resistance to pitting, crevice corrosion and intercrystalline corrosion. It possesses almost complete resistance to chloride induced stress corrosion cracking.
625 has great resistance to acids, such as nitric, phosphoric, sulfuric and hydrochloric, as well as to alkalis makes possible the construction of thin structural parts of high heat transfer. It also possesses immense resistance to oxidation at elevated temperatures up to 1050 °C. Inconel 625 may be machined by conventional means. However the alloy tends to work harden ahead of cutting and rigid tooling is essential to avoid chatter and work hardening in front of the tool edge.
This alloy can be cold formed by conventional means and tooling. The alloy does work harden during cold working with an attendant increase in strength. This increase in strength may be of value for moderate temperature applications and, in these instances, the formed parts can be left in the cold work hardened condition. Welding is readily accomplished using matching alloy filler metal for the conventional welding techniques. Hot forging may be done by heating the billet to 2100 – 2150 °F, but not over 2150 °F. Heavy forging may then be done down to a billet temperature of 1850 °F and light forging down to 1700 °F. Final reduction of 15 to 20% minimum is recommended to maintain proper grain structure.