MAGNETIC-PROPERTIES OF MARAGING STEELS IN RELATION TO NICKEL CONCENTRATION

Magnetic properties of maraging steels have been investigated as a function of nickel concentration. The alloys nickel content varied from 12 to 24 wt pet, while other alloying constituents were kept at a level maintained in the 18Ni-2400 MPA-grade maraging steel. The magnetic properties were determined following aging for 1 hour in the temperature range of 450 degrees C to 750 degrees C. In every alloy investigated, the coercive field increased with aging temperature, reaching a maximum around 670 degrees C +/- 30 degrees C. The saturation magnetization values were lowest around temperatures where maximum coercive field was observed. The coercive field increased from similar to 55 to similar to 175 Oe (similar to 4380 to similar to 13,900 amp/meter) and the corresponding saturation magnetization decreased from similar to 18,500 to similar to 4000 G (similar to 1.85 to similar to 0.4 T) in the alloys containing 12 and 24 wt pet Ni, respectively. The reverted austenite increased from 25 vol pet at 12 wt pet Ni to 100 vol pet at 24 wt pet Ni. The hardness and Charpy impact strength of the alloys have also been determined. An attempt has been made to correlate magnetic properties with different phase transformations occurring in maraging steels.