What is the difference between Alloy 400 and Alloy 500?

There is negligible difference in the composition of Alloy K500 versus Alloy 400, therefore their corrosion resistance is comparable. However, the strength level of Alloy 400 is much lower, which is why Alloy K500 was developed.

Alloy 400 (Monel 400, UNS N04400, 2.4360) is a nickel-copper alloy that is resistant to seawater and steam at high temperatures which is frequently used in the chemical, oil and marine industries. Alloy 400 is a solution strengthened material that displays good toughness, strength and corrosion resistance at temperatures up to 400°C.

Alloy 400 exhibits good resistance to hydrofluoric and dilute non-oxidising acids, alkalis and salts plus it is not susceptible to stress corrosion cracking.

Alloy K500 (Monel K500, UNS N05500, 2.4375) contains small additions of both aluminium and titanium (3-4% in total). The aluminium and titanium combine to form microscopic precipitates, which can be controlled through heat treatment. After forging or rolling, the round bars are subjected to an ageing heat treatment where they are held at an elevated temperature for several hours and allowed to cool slowly in air. This process ensures that as much of the aluminium and titanium is able to precipitate out of solution and form a widely-dispersed fine network. These precipitates create a significant uplift in mechanical properties – the yield strength can be up to 4x greater, and the tensile strength up to 2x greater.

Langley Alloys stocks a wide range of Alloy K500 from 5/8” up to 10” diameter solid round bar.