Method for production of alloyed titanium welding wire

1. A method for producing a weldable wire of alloyed titanium, wherein the method comprises the following successive process steps:

a) forming a green object by:

blending particulates of titanium sponge with a particle diameter in the range from 0.5 to 10 mm with one or more powdered alloying additions with particle size in the range from 50-250 μm; and

cold compacting the blended mixture and subjecting the blended mixture including lubricant to a pressure in the range from 750 to 1250 MPa;

b) forming an elongated profile of alloyed titanium by:

heating the green object in a protected atmosphere up to a temperature in the range from 1000 to 1250° C. 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 of alloyed titanium;

c) forming the welding wire of alloyed titanium by:

rolling the elongated profile of alloyed titanium in a rolling mill with one or more rolls placed in series to form the weldable wire with the desired diameter.

2. A method according to claim 1 , wherein the particles of titanium sponge are crushed and sheared titanium sponge of magnesium reduced, vacuum distilled titanium sponge satisfying the ASTM standard B299-07.

3. A method according to claim 2 , wherein the crushed and sheared titanium sponge has a particle size fraction in one of the following ranges: from 0.5 to 8 mm, from 1 to 6 mm, or from 1 to 4 mm.

4. A method according to claim 1 , wherein the compacting of the blended mixture is performed at room temperature with a compacting pressure in the range from 1100 to 1200 MPa.

5. A method according to claim 1 , wherein compaction is performed in an uniaxial press which comprises a floating stress ring and a floating press ram, wherein walls of the press ring is coated with a lubricant selected from a metal stearates or an amide wax.

6. A method according to claim 5 , wherein

the lubricant is also blended into the mixture and the green object is subsequent to compaction heated to a temperature in the range from 200-400° C. and held at this temperature for a period of 0.5 to 10 hours.

7. A method according to claim 5 , wherein the lubricant is zinc stearate or N,N′ ethylene bisstearamide.

8. A method according to claim 1 , wherein step b) of forming the elongated profile of alloyed titanium is obtained by:

heating the green object in a protected atmosphere up to a temperature of approximately 1100° C. and holding the temperature for a period of 6-8 hours; and then

hot extruding the green object at a temperature of less than 200° C. from the beta transition temperature of the titanium alloy.

9. A method according to claim 1 , wherein

step b) of forming the elongated profile of alloyed titanium is obtained by:

heating the green object in a protected atmosphere up to a temperature of approximately 1100° C. and holding the temperature for a period of 6-8 hours; and then

hot extruding the green object at a temperature of less than 200° C. from the beta transition temperature of the titanium alloy; and

step c) of forming the welding wire is obtained by:

shaping the elongated profile of alloyed titanium to a drawing wire by:

i) annealing the elongated profile at about 400-600° C. for a period from 10 to 60 minutes;

ii) rolling the elongated profile to reduce its diameter in a rolling mill; and

iii) repeating steps i) and ii) until the diameter of the elongated profile becomes in the range from 1 to 4 mm;

and then

shaping the drawing wire to the welding wire by:

j) annealing the drawing wires at about 400-600° C. for about 10-60 minutes;

jj) drawing the drawing wire to reduce its diameter in a per se known manner; and

jjj) repeating steps j) and jj) until the wire obtains the intended diameter of the welding wire.

10. A method according to claim 9 , wherein each pass through the rolls of the rolling mill reduces the diameter of the elongated profile from 5 to 35%.