UGIPERM® 12FM Cold Worked and Magnetic Annealed

UGIPERM® 12FM Cold Worked and Magnetic Annealed introduction

UGIPERM® 12FM is a free-machining ferritic stainless steel containing 12% chromium and an addition of silicon. This grade, which was developed for magnetic applications, has high permeability and a particularly low coercive field. It is specially designed for the manufacture of electromechanical actuators such as electro-injectors or solenoid valves. In addition, its high electrical resistivity makes it possible to obtain short activation times suitable for dynamic magnetic loads, by limiting losses due to eddy currents. The chemical analysis of UGIPERM® 12FM has been optimised to ensure good machinability properties that are particularly suited to the manufacture of mass-produced parts by bar turning. This grade has high magnetic characteristics and medium corrosion resistance, similar to that of 430FR / 4105Si.

In the as-delivered condition, the microstructure of UGIPERM® 12FM consists of ferrite, chromium carbides and manganese sulphides. It is therefore ferromagnetic ("attracted to a magnet").

Optimal magnetic properties are achieved after magnetic annealing that makes it possible to obtain a large-grained recrystallised microstructure. This heat treatment can either be performed by Ugitech on the delivered bars (after cold drawing and before surface finishing) or on machined parts by the customer.

UGIPERM® 12FM has higher magnetic properties than those of grades 430FR / UGI® 4005Si and IMRE / UGI® 4106. It is similar to iron-silicon steels, but has far better corrosion resistance properties, due to its chromium and molybdenum content and approximately double electrical resistivity. The magnetic properties of different ferritic grades, in the form of annealed drawn bars, are compared in the following table (indicative values):

Grade
UGIPERM® 12FM
UGI 4511
IMRE / UGI 4106
UGI 4105Si
Fe-Si steel

Saturation polarisation Js (T)
1.69
1.64
1.50
1.54
≥ 2.0

Coercive field Hc (A/m)
130
130
150
150
< 80

Maximum relative permeability µ_rmax
2000
2000
1600
1600
≥ 4000

Residual magnetism Br (T)
0.8
0.8
0.7
0.6
0.2 to 0.7

Resistivity ρ (µΩ.mm)
790
580
760
780
400

Equivalent material: DIN 1.4045, EN 1.4045