The niobium process-In-house skill in forging, rolling, machining, cutting and fabrication
May 26, 2017

Niobium Process

The niobium process involves:

In-house skill in forging, rolling, machining, cutting and fabrication

Skill in thermal processing

Chemical, mechanical, and microstructure monitoring on site

Reliable grain size and texture control

Avoiding Crucible Defects with Niobium Sheet

When designing a deep draw process, there are several variables to consider. An error setting on any of the steps could lead to defects in the final deep drawn part.

Wrinkling in the wall happens when a wrinkled flange is drawn into the cup or clearances are very large

Wrinkling in the flange happens due to low blank holding force

Tearing happens from high tensile stresses that cause sheet thinning. Tearing also happens from high length-to-diameter (L/D) ratios, high pressure pad loads, sharp corner radii, and high punch loads

Earring happens due to anisotropic material (i.e., directionality in properties)

Surface scratches happen when the punch and die are not smooth or when process lubrication is insufficient

Radial cracks in the flanges and edge of the cup due to inadequate metal ductility

Orange peel or surface roughness happens in coarse grain metals.

A very commonly occurring defect is the “orange peel” effect caused by coarse grain sizes. A related niobium microstructure can reveal poor smoothness and flatness of the deep drawn cup as each grain tends to deform separately and non- uniformly.

Poor flatness and/or smoothness can lead to a synthetic diamond that needs extreme grinding. Similarly, a coarse grain structure tends to cause tearing of the sheet during deep draw operations.