Method for manufacturing titanium alloy wire with enhanced properties

Abstract

A method for producing reinforced titanium alloy wire, comprising forming a billet of titanium alloy with grains of a precipitated discontinuous reinforcement material such as TiB and/or TiC. The billet may be formed by the hot consolidation of a titanium alloy powder formed by gas atomization. The billet is then hot formed to reduce it to rod or coil form. The rod or coil is then subjected to successive cold drawing operations to form a reinforced titanium alloy wire of reduced diameter. The cold drawing includes periodic annealing operations under low oxygen conditions to relieve work hardening and to recrystallize the reinforcement material grains to reduce the size thereof.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a method of manufacturing titanium alloy wire and, more particularly, to such a method wherein precipitated discontinuous particulates of a reinforcement material such as TiB and / or TiC are added to the alloy and it is processed in accordance with a new and improved method wherein the reinforcement thereof by the particulates is enhanced. BACKGROUND OF THE INVENTION [0002] Processes have been reported in the literature in which a common alloy of titanium, Ti-6Al-4V, has been reinforced and enhanced by the addition of TiB and / or TiC particulates. This is significant in that the Ti-6Al-4V alloy is utilized extensively in aerospace applications and is one of the most affordable. Enhancements that enable the extension of the useful application range of such alloys without significant cost impact are of great interest to the aerospace design community. In the reported processes, a Ti-6Al-4V casting was produced with TiB and / o...

AI Technical Summary

Benefits of technology

[0006] More specifically, a preferred method comprises the formation of titanium alloy powder by gas atomization from a boron rich melt; consolidating the powder metal to bar form using hot isostatic pressing (HIP) with a pressure of about 5,000 to 45,000 psi, e.g., 15,000 psi, and a temperature of about 1,650° F. to 1,750° F. until full consolidation, yet remaining below the beta transis to avoid grain growth and grain boundary segregation; hot reduction at approximately 1500° F. to 2100° F., e.g., 1,750° F., to reduce the bar to rod or coil form and perform the initial break-up of the larger TiB grains; and cold drawing and annealing at approximately a 10 to 20 percent reduction per pass to avoid cracking. In accordance with the method of the present invention, an increased frequency of annealing steps under very low oxygen conditions serves to relieve work hardening and also recrystallizes the TiB grains to a refined size with alignment with the wire axis. This new and improved method enables the fabrication of fine titanium alloy wire with simultaneous achievement of high TiB reinforcement content and small reinforcement grain size. Other reinforcement materials may be used such as TiC, alone or in combination with TiB.

Problems solved by technology

This limitation seriously inhibits the full capability of the discontinuously reinforced titanium potential.