When TC11 titanium alloy is used to make key components such as aircraft engine compressor discs, blades, and brakes, it needs to have good room temperature mechanical properties, high temperature strength, and impact toughness. The structure of TC11 titanium alloy can be controlled through heat treatment, so that it can obtain excellent comprehensive properties.
Currently, the most conventional heat treatment system for TC11 titanium alloy is (950 -970) ℃/120 min/AC +530 ℃/360 min/AC. However, for large-size TC11 titanium alloy rods with a diameter of more than 200 mm, during the heat treatment process, the slow temperature drop in the core often causes differences in the structure and mechanical properties at different locations.
In addition, TC11 titanium alloy has a high degree of alloying and contains the easily segregated element Mo. Therefore, the alloy structure is very sensitive to process parameters during processing, and it is difficult to control the uniformity of the structure. Therefore, the distribution patterns of the microstructure and mechanical properties of large-size TC11 titanium alloy rods after heat treatment were studied in order to provide a reference for the uniformity control of the microstructure and mechanical properties in the actual production process.
(1) After heat treatment at 970 °C/120 min/AC +530 °C/360 min/AC, there are certain differences in the microstructure of different positions of large-size TC11 titanium alloy rods. Among them, the structural changes at D/2 are the most obvious, mainly manifested as an increase in α phase content, grain growth, and a decrease in β phase content.
(2) The changes in room temperature tensile properties at different locations of large-size TC11 titanium alloy rods are closely related to the microstructure. Along the length direction, the microstructure difference at D/2 is the most obvious. The room temperature tensile properties show that the tensile strength gradually decreases from the edge to the center and the plasticity increases.
(3) The microstructure of large-size TC11 titanium alloy rods has a significant impact on its high-temperature tensile strength and impact toughness. The closer to the center (D/2 and L/2), the lower the high-temperature tensile strength and impact toughness, but the high-temperature plastic changes are not obvious.
