2.1504 is the Werkstoff number for the copper-nickel alloy most commonly known as Hiduron® 130. Werkstoff numbers were developed by the German standards body DIN; the word translates roughly as "material".
Hiduron® 130 was originally known as Hidurax Special. We developed it as a high-strength, corrosion-resistant alloy for naval applications such as seals, shafts, submarine control planes and winch components. Aluminium is the key strengthening element in Hiduron® 130 (2.1504, DTD 900/4805, C72400, CuNi14Al3), forming finely dispersed ϒ' nickel-aluminium precipitate that strengthens the alloy in a similar way to Alloy K-500. Because those precipitates form through a carefully controlled forging process and age naturally during cooling, no further heat treatment is needed, making it one of the highest-strength copper alloys commercially available.
Offshore oil and gas exploration has taken Hiduron® 130 beyond its original naval and aerospace uses. High strength and fouling resistance are valuable subsea, and its galling resistance has been particularly relevant in subsea connectors and stab plates. Its physical and mechanical properties, together with fouling resistance, make it well suited to wet-mate electrical and hydraulic connectors that must operate for extended periods before requiring immediate and safe disconnection.