Rotor material type

Relative magnetic permeability (μ_r)

Open loop phase voltage (V_rms)

Steel (soft iron)

~4600

130.7 V

Stainless steel 304

1

91.34 V

Stainless steel 416

~750

128.3 V

Silicon steel

~3500

129.8 V

Electrical steel M19

~3700

130.2 V

Mild steel (1020 plain carbon steel)

~1000

128.5 V