Method for production of alloyed titanium welding wire

Abstract

A method for producing a weldable titanium alloy and / or composite wire. The method includes: a) forming a green object by blending particulates of titanium sponge with one or more powdered alloying additions and cold compacting the blended mixture and subjecting the blended mixture including lubricant to pressure; b) forming a work body of alloyed titanium by heating the green object in a protected atmosphere and holding the temperature for a period of at least 4 hours, and then hot working the green object at a temperature of less than 200° C. apart from the beta transition temperature of the titanium alloy and shaping the green object to obtain an elongated profile; and c) forming the welding wire by placing the elongated profile of the work body in a rolling mill having one or more rolls disposed in series.

Description

[0001]This application is a continuation application of U.S. patent application Ser. No. 14 / 006,412, filed Nov. 4, 2013, which was the National Stage of International Patent Application No.: PCT / IB2012 / 051346, filed Mar. 21, 2012, which claims priority to United Kingdom Patent Application No.: 1104764.4, filed Mar. 22, 2011, all of which are incorporated herein by reference. This invention relates to a method for producing a weldable titanium alloy and / or composite wire by cold compaction, extrusion and rolling of a blended mixture of titanium sponge and alloying additions and / or reinforcing particles whereby consolidation and forming is performed wholly in the solid state without melting or encapsulation of said mixture of titanium sponge and alloying additions and / or reinforcing particles.BACKGROUND[0002]Titanium alloys and composites possess superior structural efficiencies owing to their high specific stiffness and strength. However, the present production process for making tit...

AI Technical Summary

Benefits of technology

The invention is about a way to make titanium alloy or composite wire without melting the titanium. This is done by processing in the solid state using particulated titanium sponge and powdered alloying additions. This method allows for the addition of alloys or composites containing constituents with greatly different melting points to titanium. It also prevents the coarsening of reinforcing particles that solidify at temperatures above titanium's melting point. The process involves transferring the titanium billet to a preheated extrusion press chamber and applying increasing force to the back end of the billet to near-complete densification through an extrusion die with the correct geometries to ensure a smooth surface finish. The extruded titanium may then be cleaned and coiled for further handling and storage.

Problems solved by technology

However, the present production process for making titanium alloys, whereby titanium sponge particles are blended with alloying additions, such as Al, V, Fe, TiO2, Mo, and Zr, severely restricts the range of titanium alloys that are commercially feasible.

The production of titanium composites is additionally complicated by the fact that many desirable reinforcing particles are either rapidly dissolved (e.g. carbon fibers, SiC, Al2O3) or coarsen (TiB) when immersed in molten titanium.

The former leads to loss of the reinforcing particles, while the latter will be a failure initiation site under mechanical loading.

The beneficial properties imbued by the elements and reinforcing particles listed above, either alone or in combination, have not been realized, due to the processing complications inherent in ingot metallurgy that are described above.

Taking into account yield losses during subsequent handling, the cost increase in converting Ti sponge and alloying additions to bar and subsequently a weldable alloy wire represents the majority of the total cost of wire production.

The plurality of processing steps is accompanied by multiple manual handling operations and the production cost for titanium alloy weld wire renders its use as an additive manufacturing feedstock unattractive except for niche applications.

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