Abstract: A method of forming a heat exchanger tube, particularly suited for condensing applications, contemplates cold-rolling a metallic strip to emboss a hydrophobic surface texture, to thereby form an embossed surface on the metallic strip. The method includes roll forming the metallic strip to a tubular shape, with the embossed surface on the exterior of the tubular shape, and welding the edges of the roll-formed strip to form a heat exchanger tube.

Abstract: A method for forming a multi-component composite metallic tube, in particular, a bi-component metallic tube, comprises the steps of forming a coextrudable, multi-component billet including an inner component formed from a first metallic material, and an outer component formed from a second metallic material. Notably, explosive bonding is employed for bonding the first and second components to form a metallurgical bond at the interface thereof, thus forming the desired multi-component billet. The multi-component billet is subsequently heated, and coextruded to form a multi-component tubular structure, having a metallurgical bond at an interface between inner and outer layers of the composite metallic tube.