Using neutrons to study cemented carbides for cutting inserts


Swedish company Sandvik Coromant produces the latest cutting tools and inserts using pressed powder materials, like cemented carbides, which are sintered to make them into a very hard material.

The challenge

During sintering, pressed powder blanks shrink and change geometry due to density variations in the material. As this could make a cutting tool or insert unusable, it is crucial to measure such variations accurately. While X-ray tomography is often used to study such materials, this technique cannot be used for cemented carbide powder compacts containing tungsten, which strongly absorb X-rays.

The experiment

Neutron radiation has a high penetration depth and can be used to determine the density distribution in a material. Neutrons are also suitable for studying materials containing tungsten, lead and other metals. With collaborators at the Royal Institute of Technology in Stockholm, Sandvik’s researchers performed neutron radiography at the Laboratoire Léon Brillouin and tomography at the Budapest Neutron Centre on one of their powder compacts.

The results

Qualitative radiographs revealed areas of high and low density within the insert. This study demonstrates that using neutrons to determine the density variation in powder compacts with tungsten is a viable option.

The powder compact geometry used for the study.
"The measurements clearly show that the density distribution in a powder compact with tungsten can be measured using neutron tomography. This will provide us with new insights into the design of the production process."

Hjalmar Staf
Material Scientist, Sandvik