CORROSION BEHAVIOR OF SOFTMAGNETIC IRON-NICKEL ALLOYS

The corrosion behaviour of different Fe-Ni alloys containing between 3 5 and 82 wt% nickel has been investigated in a humidity test between r oom temperature and 80 degrees C. It has been found that higher nickel contents improve the corrosion behaviour. The poor corrosion behaviou r of the low nickel containing alloys can be improved by grinding and cleaning the surface. With approximately 40 wt% nickel and 8 wt% chrom ium a softmagnetic alloy has been found with a corrosion behaviour sim ilar to a high nickel alloy with approximately 80 wt% nickel. This Fe- Ni-Cr alloy achieves also approximately the same saturation induction of 0.75 T as the 80 wt% nickel containing Fe-Ni-Mo alloy. The sufficie nt low coercive force of less than 2.5 A/m after an appropriate heat t reatment and the adequate corrosion behaviour make this alloy suitable as a material for stamped parts in electromagnetic relays.