| 摘要 |
This invention is a process for making micro-multiport tubing (10) for use in heat exchangers. The tubing (10) is a flat body (18) with a row of side-by-side passageways (20), which are separated by upright webs (22). Processing of this tubing (10) involves extrusion, a straightening and cutting operation, a rolling step to reduce the thickness of the flat body (18) and to obtain ultra small voids, assembly and furnace brazing of the heat exchanger. This invention improves the grain size of the metal in the tubing (10) and also improves the metallurgical strength of the tubing (10). There is at least 10 percent change in material thickness. The strain is concentrated at the center of the web (22) and results in at least enough cold work to produce fine recrystallized grains during the brazing thermal cycle. The amount of grain growth is controlled and the improvement in the metallurgical strength is achieved. |
