Method for manufacturing heat exchangers to allow uniform expansion of tubing

摘要

A method for treating heat exchanger tubing to be expanded by fluidic or electromagnetic expansion. The tubing treatment reduces the increased material hardness of the tubing in areas where cold work has been imparted thereon. By reducing these areas which have increased material hardness, the tubing will have a substantially similar tube yield along its entire length and can therefore be expanded to substantially the same cross-sectional area throughout by either fluidic or electromagnetic expansion. After forming the cold work regions, the regions are annealed with a heat source, such as through flame or induction heating, and are gradually cooled to avoid the effects of quenching.