Abstract: A dispersion strenghened ferritic steel having excellent ductility and toughness which has been heat treated to produce a matrix having a tempered martensitic structure composed of 0.05 to 0.25% by weight of carbon, 0.1% by weight or less of silicon , 0.1% by weight or less of manganese, 8 to 12% by weight of chromium, 0.1 to 4.0% by weight in total of molybdenum and tungsten, and 0.02% by weight or less of oxygen (exclusive of oxide particles) with the balance being iron and inevitable impurities and, homogeneously dispersed in the matrix, composite oxide particles comprising Y.sub.2 O.sub.3 and TiO.sub.2 in an amount of 0.1 to 1.0% by weight in total of Y.sub.2 O.sub.3 and TiO.sub.2 and a TiO.sub.2 to Y.sub.2 O.sub.3 molar ratio of 0.5 to 2.0.

Abstract: A grinding machine includes a casing having intake apertures for introducing the air and discharge apertures for discharging the air. A motor is mounted within the casing and has a rotatable shaft. A fan member is fixedly mounted on the shaft for rotation therewith and has a mounting portion and a plurality of blades provided on the mounting portion for flowing the air through the casing from the intake apertures to the discharge apertures for cooling the motor. A grinding wheel is secured to the mounting portion.