Method for preparing ultrafine grain titanium alloy by using alpha'' orthorhombic martensite microstructure

A technology of orthorhombic martensite and titanium alloys, which is applied in the field of preparation of ultra-fine-grained titanium alloys to achieve the effect of reducing processing costs

Inactive Publication Date: 2015-03-25
CENT SOUTH UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide a method for preparing ultra-fine-grained titanium alloy by using α"orthorhombic martensite microstructure. It can be us...

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  • Method for preparing ultrafine grain titanium alloy by using alpha'' orthorhombic martensite microstructure
  • Method for preparing ultrafine grain titanium alloy by using alpha'' orthorhombic martensite microstructure

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Embodiment 1

[0025] A Ti-6Al-2Sn-2Zr-3Mo-1Cr-2Nb-0.1Si (TC21, Mo equivalent of 5.27) alloy hot-forged sample with a size of Ф40×60mm was used. By measuring its phase transition point T β About 965°C. Put the sample in a vacuum of 1×10 -3 Heating to 1000°C in a vacuum state of Pa, and quenching and cooling to room temperature with water after holding for 1 hour, the XRD analysis of the product shows that the quenched alloy is mainly composed of α"orthorhombic martensite. Then the sample is heated by induction Heating to the deformation temperature of 750°C, holding the temperature for 3 minutes, and forging on the hot forging machine, the deformation strain rate is about 20s -1 , with a total deformation of 68%, jet cooling after the forging is completed. Finally, the forged titanium alloy is subjected to stress relief annealing treatment in a vacuum heat treatment furnace at a treatment temperature of 450° C. for 4 hours, and air-cooled to room temperature. The microstructure of the de...

Embodiment 2

[0027] A Ti-3Al-4Mo-4.5V (Mo equivalent of 7.2) alloy hot-forged bar with a size of Ф35×50mm was used. By measuring its phase transition point T β About 870°C. Put the bar in a vacuum of 1×10 -3 Heating to 900°C under Pa vacuum, keeping it warm for 1.5 hours, then quenching and cooling to room temperature with helium+nitrogen mixed gas. The XRD analysis of the product shows that the quenched alloy is mainly composed of α"orthorhombic martensite. Then the quenched bar is heated to the deformation temperature of 680°C by induction heating, and kept for 5 minutes. Extrusion deformation is carried out on the hot extrusion machine, the extrusion ratio is 5, and the jet cooling is carried out after the extrusion is completed. Finally, the extruded titanium alloy is subjected to stress relief annealing treatment in a vacuum heat treatment furnace, the treatment temperature is 400 ° C, and the time is 3 Hours, air-cooled to room temperature. The microstructure of the deformed Ti-3A...

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Abstract

The invention discloses a method for preparing an ultrafine grain titanium alloy by using an alpha'' orthorhombic martensite microstructure. According to the method disclosed by the invention, based on the characteristic that a full alpha'' orthorhombic martensite structure can be obtained by using a double-phase titanium alloy consisting of specific components and having Mo equivalent of 4-8%, and by using a unique texture characteristic of alpha'' orthorhombic martensite, an ultrafine grain double-phase titanium alloy can be prepared by virtue of thermal deformation. The method specifically comprises the following steps: firstly, performing heat treatment on a deformed titanium alloy forging stock or sheared billet at Tbeta-Tbeta+80 DEG C (Tbeta is a beta phase transformation point), and quenching to room temperature to obtain the full alpha'' orthorhombic martensite structure; secondly, forging at Tbeta-(150-300) DEG C, and performing compressional deformation and block cold treatment; and finally, performing relief annealing treatment at 400-500 DEG C to obtain an ultrafine grain double-phase titanium alloy. By adopting the method disclosed by the invention, an ultrafine grain structure of which the average grain size is less than 0.5 micron can be obtained under the condition of small deformation, so that the method is suitable for various plastic deformation manners such as forging and extruding and is simple to operate; requirements can be met by virtue of conventional equipment; and therefore the method has a good application prospect.

Description

technical field [0001] The invention relates to a method for preparing an ultrafine-grained titanium alloy in the technical field of material science, in particular to a method for preparing an ultrafine-grained titanium alloy by using an α" orthorhombic martensitic microstructure. Background technique [0002] Titanium alloy has low density (4.51g / cm 3 , about 40% of steel), high strength (up to 1000MPa or more), good fatigue resistance (the fatigue limit is twice that of steel), excellent corrosion resistance, good biocompatibility, non-magnetic and other advantages, has been enjoying the " The reputation of "space metal" and "ocean metal" has been widely used in medical applications, automobile manufacturing, aerospace and shipbuilding industries. Obtaining sub-micron or even nano-scale ultrafine-grained titanium alloys by refining the structure of titanium alloys can significantly improve the strength, fracture toughness, fatigue resistance and other properties of titan...

Claims

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Application Information

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IPC IPC(8): C22F1/18
CPCC22F1/183
Inventor 刘彬刘咏相春杰曹远奎吴宏谭艳妮
Owner CENT SOUTH UNIV
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