HIGH CARBON STEEL STRIP AS MATERIAL OF HARDENED STEEL STRIP FOR VALVE

摘要

PURPOSE:To obtain a high carbon steel strip having superior fatigue resistance and flatness and suitable for use in the manufacture of a hardened steel strip for a valve by specifying the average grain size of spheroidal carbides in a hot rolled high carbon steel strip. CONSTITUTION:A hot rolled high carbon steel strip is pickled and subjected to repeated annealing and cold rolling to obtain a high carbon steel strip (strip steel) of a prescribed thickness. At this time, the finish annealing temp. is properly selected so as to adjust the average grain size of spheroidal carbides in the steel strip to =0.7mum. The resulting high carbon steel strip is hardened and tempered to manufacture a hardened steel strip for a valve with prescribed hardness.