Ternary or quaternary alloy coating for steam ageing and cured humidity adhesion elongated steel element comprising a ternary or quaternary brass alloy coating and corresponding method

An elongated steel element comprising individual steel wires or steel filaments having a roughness Ra ranging from 0.10 μm to 2.0 μm, and said elongated steel element being covered with a coating comprising a ternary alloy or quaternary alloy coating of copper-M-zinc,

• where M is one or two metals selected from the group consisting of cobalt, nickel, tin, indium, manganese, iron, bismuth and molybdenum,
• a copper content inside said coating ranging from 58 weight percent to 75 weight percent,
• a content of said one or two metals inside said coating ranging from 0.5 weight percent to 10 weight percent,
• a remainder being zinc and unavoidable impurities,
• said one or two metals being present throughout said coating,
• phosphorus being present on said coating in an amount of more than 1 milligram per square meter of said coating and less than 4 milligram per square meter of said coating, said phosphorus amount being measured via an Inductively Coupled Plasma technique,
• said coating further comprising residues of one or more compounds selected from the group of triazoles, imidazoles, and indazoles, as measured by a ToF-SIMS technique, and
• said elongated steel element is configured to reinforce tire rubber products.

A process for manufacturing an elongated steel element comprising the following steps:

• a. coating an elongated steel element with a coating of a ternary alloy or a quaternary alloy of copper-M-zinc, where M is one or two metals selected from the group consisting of cobalt, nickel, tin, indium, manganese, iron, bismuth and molybdenum, a copper content inside said coating ranging from 58 weight percent to 75 weight percent, a content of said one or two metals inside said coating ranging from 0.5 weight percent to 10 weight percent, a remainder being zinc and unavoidable impurities, said one or two metals being present throughout said coating;
• b. drawing said coated elongated steel element in an aqueous lubricant containing a phosphorus compound, an amount of phosphorus compound being such that phosphorus is present on said coating in an amount of greater than 1 milligram per square meter of said coating and smaller than 4 milligram per square meter of said coating, said phosphorus amount being measured via an Inductively Coupled Plasma technique,
• said lubricant further having one or more compounds selected from the group of triazoles, imidazoles, and indazoles, such that said coating has residues of said one or more compounds as measured by a ToF-SIMS technique,
• said elongated steel element having a roughness Ra ranging from 0.10 μm to 2.0 μm, and
• said elongated steel element being configured to reinforce tire rubber products.