TC18 titanium alloy large size bar forging process

TC18 titanium alloy nominal composition of Ti-5Al-5Mo-5V-1Cr-1Fe, is a high strength, high toughness titanium alloy. Prominent advantage of the alloy annealed state that is under a high level of intensity (1080MPa), the use of enhanced heat treatment strength up to 1300MPa. And excellent hardenability, cross-section thickness of up to 250mm, due to cross-section thickness is not subject to hardenability, especially for large-scale aircraft bearing components, which is the most prominent TC18 titanium alloy advantages, which can be used at ordinary low-cost Forging (carried out on forging hammers), hot forging and isothermal forging, and many other processes produce forgings approaching the final shape. The alloy of the Il -76 aircraft such as access to a large number of applications.

Researchers through the TC18 titanium alloy ingot billets, and then using three different forging process to get Ф400mm bar, and the resulting bar after the same heat treatment, the obtained microstructure, mechanical properties and other results were compared Analytical research, to obtain TC18 titanium alloy large-scale bar ideal forging process.

Test using three vacuum self-consumption arc furnaces smelting Ф804mm, ingot weight 4000kg ingot. (Α + β) / β phase transition temperature of 860 ~ 870.

The ingot is heated in the zone β, and is bullet-forged by a hydraulic press. Then, different forging processes are used to heat the forging in the single-phase zone or the α + β zone after multiple fire to finally form a Ф400mm bar. The resulting rod after the same heat treatment for sampling, performance testing. Detailed process plan is as follows:

Process one: billet + high and low + 30% two-phase zone deformation;

Process two: billet + high and low + 70% ~ 85% two-phase zone deformation;

Process Three: billet + high and low, water quenching + 70% ~ 85% two-phase zone deformation.

Research indicates:

(1) Compared with the other two process schemes, the microstructure of the ф400mm bar obtained by the third process (billet + high and low, water quenching + 70% ~ 85% deformation forging process) degree is better than other programs.

(2) The strength index of the Ф400mm bar obtained by adopting the process three (billet + high and low, water quenching + 70% ~ 85% two-phase zone deformation forging process) due to the fine grain strengthening mechanism ensures the plasticity index highest. And because the process of three small and uniform grain growths, crack growth through the growth of the process so that the resulting fracture toughness index increased significantly, the best overall performance.