RELATION BETWEEN MICROSTRUCTURE AND CHIPPING RESISTANCE OF FE-SI-AL ALLOYS

Cast Fe-Si-Ai alloys containing 0.5%Ti, 0 similar to 0.06%C, 0.2% rare earth metal, were prepared using a 10-kg vaccum induction furnace. Fe-Si-Al alloy cores for magnetic recording head were produced by grinding from those alloys which were hot-rolled and annealed at 900 similar to 1100 degrees C. In this paper, the effect of grain size on chipping resistance in rough cutting, groove grinding and fine cutting of head-cores process is studied. The results obtained are as follows. 1 The methods to obtain a fine grain size of Fe-Si-Al alloy are ''hot-rolling'' and ''adding the minimum quantity of inhibiting grain-growth elements C, Ti, M. M. to alloy''. The former is the best method to obtain alloys with fine grains. 2 The larger the grain size in Fe-Si-Al alloys, the more the number of chips increases. 3 Both the depth and the number of chips are larger in cast alloys than hot-rolled and annealed alloys. 4 Alloys with fine grains are obtained by the adding two elements (Ti and C) to alloys rather than adding one element (Ti or C).