Method of acquiring tri-modal microstructure in near-alpha titanium alloy through furnace cooling

Abstract

The invention provides a method of acquiring a tri-modal microstructure in a near-alpha titanium alloy through furnace cooling. According to the method, near-beta temperature heat-insulating water cooling and two-phase region temperature heat-insulating furnace cooling and air cooling are carried out so as to obtain the near-alpha titanium alloy with the tri-modal microstructure; 10 to 20% of an equiaxial primary alpha phase can be retained in a titanium alloy microstructure through the near-beta temperature heat-insulating water cooling, with the balance being martensite; and a tri-modal microstructure titanium alloy consisting of equiaxial alpha, sliver alpha and a beta transformation microstructure is finally formed through the two-phase region temperature heat-insulating furnace cooling and air cooling. The method provided in the invention needs no near-beta thermal deformation and does not generate non-uniform deformation heat effects, temperature can be easily controlled, and special pretreatment does not need to be carried out on the equiaxed-structure near-alpha titanium alloy so as to acquire a duplex microstructure. The thickness value of secondary flake alpha in the invention is in a great adjustable range; the method is simple and easy to implement, has a wide application scope and is applicable to heat treatment of near-alpha titanium alloy parts manufactured by using methods like rolling, extrusion and machining molding.

Description

technical field [0001] The invention relates to the technical field of thermal processing of titanium alloys, in particular to a heat treatment method for obtaining a triple-state structure by using furnace cooling in near-alpha titanium alloys with equiaxed or double-state structures. Background technique [0002] Near-α titanium alloys have better thermal stability and weldability than α+β-type titanium alloys, and better pressure processing performance than α-titanium alloys. They are usually used in key load-bearing structural parts in aviation, aerospace and other fields. These components are served in harsh environments, requiring not only high precision, but also high performance and high reliability, that is to say, good room temperature strength plasticity, fracture toughness, fatigue performance, crack growth resistance and high temperature performance. The microstructure of titanium alloy determines the service performance. Equiaxed microstructure and lamellar mi...

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Problems solved by technology

[0004] In order to overcome the problems in the prior art that the temperature range is narrow, it is not convenient to control the forging temperature, and the limitation of the initial structure is a two-state structure, and the thickness of the secondary lamellar α in the obtained three-state structure is too small problem, the present invention proposes a method for obtaining a triple-state structure in a near-alpha titanium alloy by furnace cooling

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