Hot working method for improving structure property of Ti5553 titanium alloy

Abstract

The invention discloses a hot working method for improving structure property of Ti5553 titanium alloy, which comprises the steps of: firstly, performing two-phase region re-forging (alpha equiaxial+ beta transformation) on a titanium alloy blank; and then, performing beta forging on the re-forged blank (the beta forging is a forging method of heating above phase transformation point); and finally, performing beta thermal treatment to primarily form a fine and dense net basket structure after the re-forging operation; and a fine flaky alpha phase inversion in beta crystal grain and a fine, disperse and discontinuous alpha phase inversion at the crystal boundary are generated during the final beta thermal treatment process to improve the comprehensive structure property of the beta titanium alloy. By means of the heating re-forging in two-phase region (alpha equiaxial+ beta transformation) and the beta forging, nucleation energy and broken crystal structures formed by relatively large deformation quantity lay a good foundation for improving the flaky alpha phase inversion and the granular beta phase inversion in the successive beta thermal treatment, so as to obtain a member with uniform, fine and dense structure and good comprehensive performance indexes.

Description

technical field [0001] The invention belongs to the field of material processing, and relates to a titanium alloy thermal processing method for obtaining a high-strength, high-toughness fine-textured basket structure. Background technique [0002] Ti5553 titanium alloy, whose expression is Ti-5Al-5Mo-5V-3Cr, belongs to β-type titanium alloy, and is currently mainly used in more than 20 kinds of landing gear and wing structures of Boeing 787 aircraft and Airbus A350 aircraft. Load-bearing parts, replacing the original Ti-6Al-4V and Ti-1023 alloys. According to statistics, the application of Ti5553 alloy can reduce the total mass of the aircraft by 8%. The successful development of this material has enabled it to be popularized and applied in domestic C919 and other large civil aircraft projects, and can also be further promoted and applied to structural parts of other military aircraft projects. [0003] For this alloy, different types of microstructures can be obtained due...

AI Technical Summary

Problems solved by technology

[0004] The original thermal processing method of the alloy generally adopts (α 等轴 +β 转 ) Two-phase zone forging + β heat treatment method (that is, heat treatment method above the phase transition point), although the obtained structure is also a basket structure, but the primary α phase is α 等轴 Compared with thicker, β 转 The grain boundaries of the β grains on the matrix are composed of continuous straight and thick sheet-like α 转 Phase formation leads to a decrease in material strength, which in turn affects the reliability of components. Therefore, it has always been a major problem to solve the problem of matching the comprehensive performance indicators of Ti5553 titanium alloy strength and toughness.

However, due to the limitations of technical conditions and design ideas, the ideal processing technology has not been researched in China to obtain this ideal β-type titanium alloy structure.

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