Materials of SFMC Non-magnetic drill collars are made from chrome manganese low carbon austenitic alloy, which has following characteristic:

The chemical composition should be controlled strictly during the refining and forging process.

With excellent lower Magnetic permeability, high strength of mechanical properties and outstanding resistant to stress corrosion cracking and no tendency to galling.

Mechanical properties

SFMC non-magnetic has the listed mechanical properties along its overall length.
Non-magnetic properties   
Magnetic permeability (when MPS=1×105/4πNm)
* Relative Max: 1.010
* Average: μr≤1.005

Magnetic Field Gradient (hot spots)
* Max: B ≤ 0.05 micro Tesla/100mm