Research on Cold Drawn Deformation Behavior and Microstructure of TC4 Titanium Alloy
|School||Dalian University of Technology|
|Course||Materials Physics and Chemistry|
|Keywords||TC4 Titanium alloy Lubricate coating Cold drawn Deformation mechanism Recrystallization|
Titanium alloy wire as a kind of titanium, are widely used in aviation, spaceflight, medical, automotive, etc, because of their good properties such as corrosion resistance, high specific strength, and antimagnetic. Cold drawing process of titanium alloy wire production was studied in detail. The discussing result was significant for the production technology of titanium wire, the improvement of the technology level and equipment to our country. The investigation concluded the cold drawn plastic deformation of titanium wire, the evolution of the microstructure and mechanical properties in cold drawn plastic deformation. Recrystallization kinetics and the cold deformation mechanism of TC4 titanium were also studied. The results were as follows:(1)Cold drawn plastic deformation of TC4 titanium alloy wire can be realized with reasonable drawing speed, pass deformation, lubrication condition. The cold drawn strain of 0.90 could be realized after 6 continuously multi-pass drawing.(2)Surface of titanium alloy formed a dense chemical conversion film in chemical conversion liquid. Its conversion film as the lubrication coating, had adsorptive lubricant effect, made wire a smooth surface after multi-pass drawing, and there were no adhesion and scratches.(3)With increasing of cold drawn strain, tensile strength increased, plastic decreased. At strain of 0.90, tensile strength of titanium alloy achieved 1200 MPa, nearly 30% higher than that of annealing state. It’s the composite result of dislocation strengthening and grain refining. Wires presented a pronounced<1010> fibrous texture along the drawing axial direction, with the increase of cold drawn strain, texture types did not change, and strength was increasing.(4)Recrystallization process of cold worked titanium alloys can be concluded as recovery nucleation and grain growth stages. It shown that the recovery involved rearrangement of dislocation cells into subgrains, formation of nuclei through growth or coalescence of subgrains, growth of nuclei by high angle boundary migration during the annealing of the titanium alloy. The recovery subgrains with particular crystal orientations provided preferential sites for the nucleation during subsequent recrystallization annealing and grew to be new grains. The texture at the end of primary recrystallization was consistent with the deformed state depending on the crystallographic orientation.