METHOD FOR TREATING HOLLOW STEEL RODS

摘要

The invention relates to manufacturing hollow drill steel, preferably in the form of percussion drilling rods. For improving operation strength of rods and increasing service life of thermal equipment elements the rods are carbonized in an atmosphere containing ammonia at temperature of 870-880 degree C, then hardened twice with an intermediate high-temperature tempering, wherein second hardening is carried out in liquid hardening medium simultaneously for both outer and inner surfaces with compressive forces applied to the rod side surface and radial directed to its section center.