TC6 titanium alloy plate is a martensitic Ti-Al-Mo-Cr-Fe-Si system α + β two-phase heat-strength titanium alloy with good comprehensive performance, its nominal composition is Ti-6Al-2.5Mo-1.5Cr -0.5Fe-0.3Si, α / β transition temperature is between 960 ～ 1000 ℃.
In addition to the advantages of ordinary titanium alloy, such as high specific strength and good corrosion resistance, the alloy also has good comprehensive mechanical properties at room temperature and high temperature, and the use temperature can be as high as 450 ℃. It is often used in the manufacture of aircraft engine blades, turbine disks, etc Components can also be used to manufacture aircraft bulkheads, joints and other parts. A large amount of work has been done on the machining technology and performance optimization of TC6 titanium alloy forgings, castings, tubes and rods in China. However, there are few studies on TC6 alloy plates. Researchers have determined by controlling the cold rolling process of TC6 plates The basic process parameters of cold rolling of TC6 sheet were studied, and the cold rolling performance of TC6 sheet was studied.
The TC6 titanium alloy ingot used in the experiment was obtained by three times melting in a vacuum consumable arc furnace. Its β transformation temperature is 975 ～ 985 ℃, and the specific chemical composition is (wt.%): Al6.2, Mo2.5, Cr1.4 , Fe0.41, Si0.29, O0.10, Zr <0.01, C <0.01, N <0.01, Ti balance. The TC6 ingot was used in the experiment to open the blank in the β phase area, and the α + β two phase area was forged into a slab. The slab is hot rolled at a temperature above the β transition temperature, rolled to 3.5mm in the α + β two-phase zone, and subjected to cold rolling hardening experiments after intermediate annealing and pickling. When the machining rate increases by 5%, cut a piece of 200 mm long test material from the head of the plate, and the remaining plate continues to be rolled, so repeated rolling and sampling until the plate shows edge cracks or surface cracks. Then, the 200mm experimental materials with different machining deformations were tested, and the thickness, spread, edge crack, structure and mechanical properties of the experimental board were tested respectively.
The above experimental microstructure was observed on an Axiovert 200 MAT optical microscope, and the mechanical properties were tested on an Instron 5885 tensile testing machine. The test results are as follows:
- (1) It can be found from the cold-rolling work hardening curve that the tensile strength and yield strength increase with the increase of the machining rate, while the elongation rate gradually decreases, which is mainly due to the increase of the dislocation density with the increase of the cold-rolling machining rate , Work hardening intensified. When the machining rate reaches about 27%, the tensile strength and yield strength curves tend to be horizontal, indicating that it is difficult to deform.
- (2) The maximum cold-rolling machining rate of TC6 titanium alloy plate can reach 30.3%, and the elongation of the material is reduced to 5.8% at this time. Observe that the surface of the plate begins to wrinkle and emboss, and cracks appear on the edges. When the cold rolling machining rate reaches 30.3%, the width extension is 20mm.
