Effect of nickel and manganese addition on ductility and magnetic properties of 6.5% silicon-iron alloy

The effect of nickel and manganese addition on the ductility and magnetic properties of 6.5% silicon-iron sheet has been studied. Ductility was studied by tensile tests and cold-rolling under various conditions. It was found that the nickel addition did not improve the cold-workability of the alloys. Alloys with 0.10-0.17% manganese can be cold-rolled from a thickness of 1 mm to less than 0.35 mm after hot-rolling with above 80% reduction at about 600-700°C and a subsequent annealing at 600°C for 1 h. This might be due to the small grain size caused by the manganese addition and the removal of internal stress without crystal growth by annealing at 600°C. The effect of nickel and manganese addition on the magnetic properties of 6.5% silicon-iron alloy is fairly small for nickel content of less than 4% and manganese content of less than 0.20%. A maximum permeability of 35 000 occurs at about 0.15% manganese content and at annealing temperature of 900°C for 20 h.