Heat treatment method for improving fatigue performance of selective laser melting alpha-beta type titanium alloy

Abstract

The invention belongs to the field of advanced manufacturing of metal materials, and relates to a heat treatment method for improving the fatigue performance of selective laser melting alpha-beta type titanium alloy. In the method, after the alpha-beta type titanium alloy is subjected to stress annealing and hot isostatic pressing treatment, high-temperature aging treatment at the temperature of (Tbeta-350)-(Tbeta-250) DEG C is carried out, the alpha-beta type titanium alloy obtained after heat treatment contains a small amount of equiaxed alpha phases, and the obtained selective laser melting alpha-beta type titanium alloy workpiece is subjected to heat treatment. Original coarse beta grains generated in the selective laser melting forming process and needle-like martensite alpha' phases in the grains disappear are replaced by near basket structures composed of beta matrixes, lamellar alpha phases and a small amount of equiaxed alpha phases. Meanwhile, defects such as micropores and microcracks in the titanium alloy workpiece are closed, a basket-shaped structure composed of lamellar alpha phases has good fatigue strength, and a small amount of equiaxial alpha phases mixed in the basket-shaped structure can increase the expansion difficulty of fatigue cracks, so that the fatigue performance of a workpiece is remarkably improved.

Description

technical field [0001] The invention belongs to the field of advanced manufacturing of metal materials, and relates to a heat treatment method for improving the fatigue performance of laser selective melting α-β titanium alloys, in particular to a method for improving the fatigue performance of laser selective melting α-β titanium alloys without sacrificing strength and plasticity. Heat treatment methods for fatigue properties of titanium alloys. Background technique [0002] Titanium alloy has good mechanical properties at room temperature and high temperature, and has many performance advantages such as low density, high specific strength, high corrosion resistance, etc., and is widely used in cutting-edge fields such as aerospace. Among them, α-β titanium alloy has good weldability and can be strengthened by heat treatment, which is very suitable for additive manufacturing technology. As advanced aerospace equipment has higher and higher requirements for weight reduction...

AI Technical Summary

Problems solved by technology

This process leads to the final formed α-β titanium alloy structure as a Widmanstatten structure composed of coarse β grains and acicular martensite α’ phase in the grains, which generally has low fatigue performance.

At the same time, random defects such as pores and microcracks are prone to occur during the laser selective melting forming process. The defects distributed on the surface or near the surface of the part often become the source of fatigue cracks, further reducing the fatigue performance and stability of titanium alloy parts.

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