Experimental Materials The material used in the experiment is the industrialized ingot of TC11 titanium alloy provided by Xi'an Northwestern Polytechnical University Super - Crystal Technology Development Co., Ltd., which has been melted three times by vacuum consumable arc. Its chemical composition meets the requirements of GB/T3620 - 2007. The ingot is initially forged by free forging at 1150 °C. After being reforged for multiple heats, it is finally drawn and rounded into a Φ280mm bar. The macro - structure of this bar is a semi - blurred crystal structure, and the micro - structure is a typical two - phase - zone deformed structure, mainly composed of equiaxed primary α - phase, with a small amount of long - strip primary α - phase, and the volume percentage of the primary α - phase is about 40% - 60%.
Experimental Scheme Experiment 1 A 100 - mm - long billet is cut from the Φ280mm bar with a bandsaw and treated according to four heat treatment regimes with different solution temperatures in Table 2. After heat treatment, six sample bars with a specification of 14mm×100mm are cut by wire - cutting respectively for mechanical property testing and analysis. Experiment 2 A 100 - mm - long billet is cut from the Φ280mm bar with a bandsaw and treated according to four different heat treatment regimes in Table 3, and mechanical property testing and analysis are also carried out. All heat - treated samples are machined and then tested for mechanical properties on an Instron - 4507 tensile testing machine, and the microstructure is observed and analyzed with a LEICAMEF4A inverted metallurgical microscope.
Experimental Results Influence of Sampling Location on Room - Temperature Mechanical Properties The overall uniformity of room - temperature mechanical properties at different sampling locations under the same heat treatment is acceptable, but the room - temperature properties of the billet edge parts (samples numbered 1#, 2#, 3# and 4#) fluctuate greatly. This is because during the hot - deformation process, under the combined action of friction and temperature drop, the deformation amount at the edge is small and the deformation uniformity is relatively poor. Influence of Solution Temperature on Room - Temperature Mechanical Properties Different solution temperatures have a significant influence on the room - temperature tensile properties of TC11 titanium alloy. When the solution temperature is increased from 940 °C to 955 °C, the room - temperature strength and plasticity change little, and the properties are in a relatively stable state; when the solution temperature is increased to 970 °C, both the room - temperature strength and plasticity decrease significantly. The tensile strength and yield strength decrease by about 50MPa, the relative elongation decreases by 8%, and the reduction of area increases by about 6% numerically. The sample has significant area reduction due to uneven deformation during tensile, resulting in a decrease in elongation; when the solution temperature continues to rise to 980 °C, compared with 970 °C, both the room - temperature strength and plasticity show a certain recovery. The tensile strength and yield strength increase by about 30MPa, and both the elongation and the reduction of area increase. Therefore, under the experimental conditions in this paper, the solution temperature of the heat treatment regime for TC11 titanium alloy should avoid 970 °C. Influence of Aging Time on Room - Temperature Mechanical Properties Different aging times have different influences on the room - temperature tensile and impact properties of TC11 titanium alloy. The aging time has no significant influence on the room - temperature tensile properties but has a significant influence on the room - temperature impact properties. Heat treatment regime B is beneficial for strength, and heat treatment regime C is beneficial for plasticity. To meet the matching of strength and plasticity, the solution temperature is increased to 965 °C, and the holding time is reduced to 1.5h. After solution treatment at 965 °C/1.5h, AC, when the aging time is extended from 4h to 6h, the room - temperature mechanical properties change insignificantly, and the impact property decreases slightly, but the fluctuation range is within the error range of impact property testing; when the aging time is increased to 8h, the microstructure is obviously spheroidized, the number of long - strip primary α - phase decreases significantly, and both the primary α - phase and the secondary α - phase grow, resulting in an increase in impact property by 30.4 - 33.6J, but the room - temperature tensile strength and plasticity change little; when the aging time continues to increase to 10h, the microstructure and room - temperature mechanical properties change little, and the impact property decreases by 6.4J compared with that at the aging time of 8h.
In conclusion, heat treatment has an important influence on the room - temperature mechanical properties of TC11 titanium alloy. In practical applications, the heat treatment regime should be reasonably selected according to specific requirements to obtain the best room - temperature mechanical properties. For example, when higher strength is required, a solution temperature of 940 - 955 °C can be selected; when better impact properties are required, the aging time can be appropriately extended, etc. Through the optimization of the heat treatment regime, the performance advantages of TC11 titanium alloy can be better exerted to meet the requirements of high - performance materials in fields such as aero - engines.