Abstract: A multi-layer metal tube consists of a flat steel band having a soldering layer connected to at least one side of the steel band. The soldering layer consists of a copper alloy having a melting point below 1020.degree.. The tube is produced by deforming the flat steel band into a tubular shape by winding or cylindrically rolling and by subsequently soldering the steel band to form the multi-layer metal tube. The soldering step prevents leaks as well as corrosion. In the corresponding method for manufacturing the multi-layer tubes the steel band in a first step is electrolytically degreased and activated in a nickel flash bath or in a copper pickling bath. Subsequently, the steel band is coated with the copper alloy which contains tin, zinc, or silver in order to reduce the melting point. After completion of the winding step or rolling step, the multi-layer tube can be coated with an additional corrosion-preventing layer.

Abstract: A cold-rolled steel strip having an electrodeposited nickel coating exhibiting a great diffusion depth, and a process for producing this strip. In order to develop a cold-rolled strip that can be produced economically, and which has a reduced tendency to stick, good deformability, deep coating diffusion, advantageous corrosion dehavior, and improved electrochemical behavior, and in order to develop a process for producing this strip, the thickness of the nickel coating should carry a coating of cobalt which has been electrodeposited to a thickness of 0.01 to 1.0 [m, and after having been coated, the cold-rolled strip should be subjected to a final heat treatment at a temperature of between 580.degree. and 710.degree. C.