Fabricating a frustrum of a cone 1

[snydes5048]

Need to make a frustrum of a cone using niobium-30w/oTi-20w/o W alloy. 0.5-inch wall thickness. Two possible fabrication techniques have been posed. Use powder met and HIP to near net shape. Roll plate and form and seam weld. The later isn't attractive for several reasons. Does anyone know if this could be forged, back extruded, etc.?

 

[TVP]

Feasibility of forging will depend on the other dimensions that you did not provide (height, width1, width2, etc.). Have you considered casting or a laser additive process? What's wrong with rolling plate and then welding?

 

[snydes5048]

Cone dimensions are base; 8-inch inside diameter; top, 4-inch inside diameter. This alloy is highly reactive - similar to tantalum. It must be hot rolled at 1800-2000F and protected from oxidation. To weld a one-half inch weld gap would require a fair amount of filler wire which would have to be fabricated separately. The roll and weld technique could be made to work. Casting is not feasible because the melting point is 3990F and we haven't found a technique to hold the material and pour it into a mold. We are looking for a more straight forward technique.

 

[EnglishMuffin]

You could roll two halves, accurately machine the joint surfaces, and then have the two halves electron-beam welded (no filler required).

 

[TVP]

I like EnglishMuffin's suggestion. The geometry does not lend itself to being forged/back extruded. If the material is available as a powder, you may want to investigate the laser additive process. I know that some fairly large titanium pieces have been fabricated this way. One supplier of this technology is Optomec:

http://www.optomec.com/html/lens.htm

You will find more options by using Google with keywords like Laser Engineered Net Shaping (LENS). Good luck.