Effect of hot band temper rolling strain on the magnetic properties of low-carbon electrical steels

The effect of hot band temper rolling strain, in the range from 0 to 0.16, on the magnetic properties of low-carbon electrical steels has been investigated at 10, 15 and 17 kG induction. After annealing at 800 degrees C for 15 min, the grain structures of hot bands were changed by various amounts of temper rolling strain. A large proportion of fine grains over almost the whole thickness and a small proportion of large columnar grains near the surface occurred in the hot band without temper rolling strain. Large irregular grains over almost the whole thickness and a small proportion of fine grains in the central part of the plates occurred in the hot bands with temper rolling strain in the range 0.04-0.08. A uniform medium size grain structure was present in the hot bands with temper rolling strain in the range 0.12-0.16. After final annealing at 820 degrees C for 1 min, low-carbon electrical steels subjected to a hot band temper rolling strain in the range 0.04-0.12 exhibited a larger grain size than the others. The texture of low-carbon electrical steel with 0.16 hot band temper rolling strain was poorer than the others. Low-carbon electrical steels subjected to a hot band temper rolling strain in the range 0.04-0.12 exhibited lower ac core loss and hysteresis loss than the others. A hot band temper rolling strain in the range 0.04-0.12 improved the ac and de permeability measured at 17 kG induction and the magnetic flux density of low-carbon electrical steels.