| 摘要 |
A process for the manufacture of metal tubes, wherein the tubes exhibit improved yield strength, axial elongation and circumferential elongation properties. The tube is initially cold worked to obtain final size, which develops a certain strength to the metal of the tube and produces uniformity in the dimensions of the tube. A subsequent annealing increases the ductility of the metal in the tube. After annealing the tube is stretched significantly with the simultaneous reduction of the diameter thereof, to obtain a final product where the wall of the tube has been work hardened by such stretching. The latter operation increases the yield strength in the tube wall without failure occurring. A process of the type indicated where the annealing is a recrystallizing annealing, effective to produce recrystallizing of the microstructure of the tube's metal, and wherein the stretching is done without internal or external support of the tube wall.
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