Product & Technology

Free-cutting Invar/Kovar

Fe-Ni alloy is generally a soft, ductile material that is difficult to cut, and customer demand has called for free-cutting. However, since S-addition causes a great loss in hot workability, it used to be a difficult steel to make it free cutting.
Yet by adding TICS as a free-cutting element, free cutting has been realized.


  1. Using TICS to attain free-cutting has dramatically improved machinability.
  2. Features such as the coefficient of thermal expansion remain unchanged.

[Form of cutting chips]

Form of cutting chips

Description of materials

[Basic composition]

  • Free-cutting invar (K-EL70CS) 36Ni-Fe-TICS
  • Free-cutting super invar (K-EL50CS) 32Ni-5Co-Fe-TICS
  • Free-cutting kovar (K-ET52CS) 29Ni-17Co-Fe-TIC


[Physical property]

Steel name Density
Coefficient of thermal expansion
Young's modulus
Modulus of rigidity
Poisson's ratio
K-EL70CS 8.12 1.4
14.3 5.55 0.29
K-EL50CS 8.14 0.6
14 5.47 0.28
K-ET52CS 8.2 5.48
13 4.82 0.35

Coefficient of thermal expansion: Upper α20-60℃, Lower α20-100℃

[Drilling test result]

Drilling test result



Please refer to Pb Free TICS Free-cutting Soft-magnetic Stainless Steel.