Abstract: A cylindrical part of a rotor for an eddy current deceleration device of the present embodiment has a chemical composition consisting of, by mass %, C: 0.05 to 0.15%, Si: 0.10 to 0.40%, Mn: 0.50 to 1.00%, P: 0.030% or less, S: 0.030% or less, Mo: 0.20 to 1.00%, Nb: 0.020 to 0.060%, V: 0.040 to 0.080%, sol. Al: 0.030 to 0.100%, B: 0.0005 to 0.0050%, N: 0.003 to 0.010%, Cu: 0 to 0.20%, Ni: 0 to 0.20%, Cr: 0 to 0.10%, and the balance: Fe and impurities, and in which the total area fraction of martensite and bainite in a microstructure is more than 95.0%, and the number density of carbides having an equivalent circular diameter of 100 to 500 nm is 0.35 to 0.75 particles/?m2.

Abstract: Provided are a granular inorganic filler which is highly effective in improving the physical properties of resins and excellent in working efficiency, working atmosphere, productivity and economical efficiency, a process for producing the filler, and resin compositions excellent in mechanical properties, surface appearance, flame retardance and antiblock properties. The filler is produced by granulating a mixture comprising inorganic filler particles having a mean particle diameter of 0.01 to 20 &mgr;m and a binder in such a way as to give an apparent density of 0.1 to 3.0 g/ml and a breakage rate of 5 to 80 wt %. The resin compositions are prepared by adding the granular inorganic filler to resins.