A heat treatment method that can significantly improve the plasticity of laser additively manufactured titanium alloys

Abstract

The invention provides a heat treatment method capable of obviously improving the plasticity of titanium alloy subjected to laser additive manufacturing. At no expense of reducing the material strength, through spheroidizing of primary alpha layered sheets, the plasticity of titanium alloy is greatly improved, and the strength of the titanium alloy is not significantly reduced. The method comprises: putting a titanium alloy sample subjected to laser additive manufacturing and having a chaotic needle-like Widmannstatten structure in a vacuum heat treatment furnace, and performing tripartite heat treatment to obtain a titanium alloy sample containing an equiaxial primary alpha phase, a needle-like secondary alpha phase, and a residual beta phase. The first heat treatment includes raising thetemperature of the alloy to 975-985 DEG C, performing heat preservation for 1 h, and then cooling the furnace to a temperature no more than 300 DEG C; the second heat treatment includes raising the temperature of the sample subjected to the first heat treatment to 910-930 DEG C with the furnace, performing heat preservation for 1 h, and performing air cooling to a temperature no more than 300 DEGC; and the third heat treatment includes raising the temperature of the sample subjected to the second heat treatment to 540-600 DEG C with the furnace, performing heat preservation for 4 h, and performing air cooling to the room temperature.

Description

technical field [0001] The invention relates to the field of advanced manufacturing of metal materials, in particular to a heat treatment method that can significantly improve the plasticity of titanium alloys manufactured by laser additive manufacturing. Background technique [0002] Due to the advantages of high specific strength, good thermal strength, and corrosion resistance, titanium alloys are widely used in aviation, aerospace, navigation and other industrial fields. α phase and β phase are two phases that exist stably in titanium alloy (Ti-6Al-4V / Ti-6Al-4V-ELI) at room temperature, and their ratio, shape, distribution, etc. determine the performance of titanium alloy. Traditional manufacturing techniques (such as forging) usually combine large plastic deformation and subsequent recrystallization to equiax the lamellar α structure, thereby significantly improving the plastic properties of titanium alloys. Due to the rapid heating and cooling characteristics of laser...

AI Technical Summary

Problems solved by technology

However, compared with the equiaxed microstructure, the coarsened α-phase morphology has a very limited improvement on plasticity.

At the same time, an inevitable disadvantage of this method is that the strength of the material is significantly reduced. The more the increase in plasticity, the more significant the reduction in strength, even below the strength standard of titanium alloys.

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