TC6 alloy is a kind of martensite 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-0.5. Fe-0.3Si, the α/β transition temperature is between 960 and 1000 °C. In addition to the advantages of high specific strength and good corrosion resistance of the ordinary titanium alloy, the alloy also has good comprehensive mechanical properties at room temperature and high temperature. The use temperature can be as high as 450 ° C, which is often used to manufacture aero-engine blades, turbine disks, etc. Parts can also be used to make parts such as frames, joints, etc. of aircraft. Domestically, a lot of work has been done on the processing technology and performance optimization of TC6 titanium alloy forgings, castings, pipe bars, etc., but there is less research on TC6 alloy plates. Researchers determine the cold rolling process of TC6 plates. The basic process parameters of cold rolling of TC6 sheet were studied, and the cold rolling processing performance of TC6 sheet was studied.
The experimental TC6 titanium alloy ingot is obtained by three times of vacuum self-consumption arc furnace melting, and its β transformation temperature is 975-985 ° C, 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 experimental TC6 ingot was opened in the β phase region, and the α+β two-phase region was forged into a slab. The slab is hot rolled at a temperature above the β transformation temperature, rolled to 3.5 mm in the α+β two-phase region, and subjected to cold rolling work hardening experiments after intermediate annealing and pickling. When the processing rate is increased by 5%, a 200 mm long test material is cut from the head of the sheet, and the remaining sheet is continuously rolled, so that it is repeatedly rolled and sampled until the sheet is cracked or cracked. Then, 200mm experimental materials with different processing deformations were tested to test the thickness, width, edge crack, microstructure and mechanical properties of the experimental plates.
The above experimental microstructures were observed on an Axiovert 200 MAT optical microscope and the mechanical properties were tested on an Instron 5885 tensile tester. The test results are as follows:
(1) It can be found from the cold rolling work hardening curve that the tensile strength and the yield strength increase with the increase of the processing rate, and the elongation gradually decreases, which is mainly due to the increase of the dislocation density as the cold rolling processing rate increases. Work hardening is intensified. When the processing rate reaches about 27%, the tensile strength and yield strength curves tend to be horizontal, indicating that it enters the difficult deformation stage.
(2) The maximum cold rolling processing rate of TC6 titanium alloy sheet can reach 30.3%. At this time, the elongation of the material is reduced to 5.8%. It is observed that wrinkles and embossing begin to appear on the surface of the sheet, and cracks appear at the edges. When the cold rolling processing rate reaches 30.3%, the width spread is 20 mm.
