What is the key to titanium rod stretching?
The process of manufacturing Nb-Ti single-core titanium alloy bars generally uses hot forging, cold rolling, and cold swaging of alloy ingots. However, flashing or other defects often occur during cold rolling or cold forging, and surface repairs are required, which is time-consuming and labor-intensive, which is very unreasonable. The process of producing Nb-Ti rods by Huachang Company in the United States is to cold-screw the extruded rods to a diameter of 12.6 mm, and then stretch them to a diameter of 3.2 mm after annealing at 800°C. This can ensure the surface finish and the roundness of the titanium alloy bar. During stretching, an emulsion of molybdenum disulfide, graphite fine powder, agar, trichloroethylene and water is mixed and coated on the surface of the titanium alloy bar, and then it is dried and stretched to achieve better results.
The cold drawing process for physical examination of Nb25—70%Zr (weight) alloy was studied. The relationship between the drawing die angle, the coefficient of friction and the drawing force was measured, and a suitable lubricant was also selected. Nb-Zr and Nb-Ti have co-extensive properties, which are completely suitable for the stretching of dry Nb-Ti rods.
Experiments have proved that the choice of lubricant is the key to the success or failure of stretching. Add graphite powder and molybdenum disulfide to water and a volatile solution to make emulsion liquid, and apply it on the surface of the titanium alloy bar. After drying, a dense film is formed on the surface of the titanium alloy bar. It has a large pressure and is not easy to fall off. The die angle of the drawing die is 12-16°, but the angle of 18-20° is better.