A method for forming a large tc17 titanium alloy integral blisk forging by β hot die forging

Abstract

The invention discloses a method for forming large-scale TC17 titanium alloy blisk forgings by β hot die forging. In the invention, TC17 titanium alloy rods are sequentially subjected to free forging, β hot die forging and heat treatment. By adjusting the processing parameters, Further refine the β-forging structure, improve the uniformity of the overall structure of the forging, and obtain the structure type that is most conducive to the matching of the strength, toughness and fatigue performance indicators of the TC17 titanium alloy blisk forging, and ensure the consistency of the overall performance of each part. The TC17 titanium alloy blisk forging prepared by the present invention has high strength, plasticity, toughness and fatigue life, and can be widely used in components such as high-pressure compressor disks and fan disks of turbofan aeroengines, significantly improving the performance of the engine and service life.

Description

technical field [0001] The invention relates to the technical field of TC17 alloy forging, in particular to a method for forming a large-scale TC17 titanium alloy integral blisk forging by β hot die forging. Background technique [0002] TC17 titanium alloy is a near-β titanium alloy rich in β stable elements. The nominal composition is (%, mass fraction) Ti-5Al-2Sn-2Zr-4Mo-4Cr. TC17 titanium alloy has high strength, good fracture toughness and Fatigue performance, and can achieve good matching, so that it has excellent comprehensive mechanical properties, and is widely used in components such as high-pressure compressor discs and fan discs of turbofan aero-engines. The maximum working temperature of TC17 alloy is 427℃. [0003] The corresponding engine model standards and industry standards stipulate that the room temperature tensile strength of the high-pressure compressor disc and fan disc forgings of TC17 titanium alloy engine should be ≥1120MPa, the elongation should b...

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Problems solved by technology

[0004] 1) In the traditional β forging process, the preheating temperature of the mold is 250-350°C, and the forging temperature of the blank is about 920-930°C. The temperature difference between the mold and the blank is too large. The large temperature gradient forms a severe chilling temperature drop on this part of the surface metal, resulting in a decrease in the plasticity of this part, insufficient deformation in the subsequent pressing process, and the formation of local coarse and uneven structures, which are reflected in low magnifications. layer, causing the strength, plasticity and fatigue properties of this part of the forging to decrease, making the room temperature tensile strength, elongation, and room temperature low cycle fatigue cycle times of the produced forging barely meet the standard requirements or even unqualified. Therefore, it is necessary to optimize the forging process to avoid occurrence This phenomenon of local structure inhomogeneity due to the severe surface temperature drop is to ensure the overall performance level of forgings;

[0005] 2) In the traditional β forging process, the preform is usually selected from the flat die upsetting preform which is less difficult to prepare, and the total deformation of the forging process is controlled to ensure the structure and performance of the forging. This process ignores the deformation of the forging during the deformation process. The distribution of the specific equivalent strain in each part of the interior. Therefore, under the premise of ensuring the total deformation, a local small strain area is often formed due to the shape of the forging. At the same time, due to the large heat capacity of the large TC17 titanium alloy blisk forging, its The temperature drop in the cooling process after forging is slower. Therefore, the formed high magnification is reflected in the coarse original β grains, the straight and continuous grain boundary α phase, and the single-phase intragranular lamella parallel α phase clustering, resulting in the plasticity of this part of the forging. Fatigue properties are all reduced, so that the elongation rate of forgings produced and the number of low-cycle fatigue cycles at room temperature barely meet the standard requirements or even fail

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