Titanium alloy with high specific strength, corrosion resistance and excellent thermal strength, etc., it has been widely used in the field of aerospace. Ti-17 alloy is a kind of excellent β-type alloy with excellent properties. Its nominal composition is Ti-5Al-2Sn-2Zr-4Mo-4Cr. The alloy can be forged in the α + β phase region or in the β phase region. It not only has a high strength, hardenability and fracture toughness, and good heat stability, fatigue performance, thermal processing performance. Since the 1970s, it has been able to enter the field of aerospace with excellent performance and also used as a compressor for higher thrust engines. With the continuous development of China's engine industry, with Ti-17 titanium forging production of high-pressure compressor as the first and second overall disc forging Ti-17 titanium rod bar specifications, organization and performance have a higher Claim. So the researchers studied the Ti-17 titanium alloy Φ350mm large-scale bar forging process.
The phase change point (α + β / β) of the experimental material alloy was measured by metallographic method from 880 to 900 ℃.
According to A, B two forging process method, we do the productionΦ350mm specifications bar.
Option A: The ingot is deformed in a single phase for upsetting, the deformation is 60-75%, then enters the two-phase area forging, the two-phase area performs the normal drawing process, the deformation amount is 60-75%;
Option B: The ingot is forged by normal drawing process, the deformation amount of single phase is 40 ~ 65%, and the deformation amount of two phase area is 40 ~ 60%. The Research indicates as following:
(1) the use of option A forging Ti-17Φ350mm bar, the mechanical properties are in line with standard requirements. The high-temperature tensile properties and creep properties of the forged bars produced in option B could not completely meet the standard.
(2) Using the forging bar produced by option A, the low magnification is homogeneous fuzzy crystal, the high power microstructure is spherical α + β transfer organization, and the transverse vertical microstructure is not very different. The low magnification of the forging bar produced by scheme B is homogeneous semi-fuzzy crystal, the high-order tissue is spherical α + flake α + block α + β transfer organization, the longitudinal organization has certain tendency, and the transverse vertical microstructure is different.
(3) The level of clutter detection for the forging bar produced by scheme A can reach Φ3.2 -9 ~ -12dB, and the level of forging stick detection clutter produced by scheme B is Φ3.2 0 ~ -3dB. The overall clutter level is high, -6 ~ -9dB.
(4) through the upsetting process, single-phase deformation is more than 60%, two-phase area with long deformation, and deformation of more than 60% of the forging process, can produce performance, organization and testing levels meet the standards and user requirements Ti-17 titanium alloy Φ350mm specifications bar, suitable for industrial mass production.
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