| 摘要 |
The invention relates to ferrous metallurgy, and more particularly to the production of free-machining structural steel with high machining properties for the manufacture of parts for use in mechanical engineering. The claimed steel contains the following components (in wt%): 0.32-0.42 carbon; not more than 0.35 silicon; 1.4-1.8 manganese; not more than 0.04 phosphor; 0.08-0.4 sulphur; not more than 0.03 aluminium; 0.03-0.12 bismuth; the balance iron and impurities. The steel has uniformly distributed slightly deformed sulphide inclusions with a score of 2.1-2.2, said inclusions having an ellipsoidal shape and a total oxygen content of 0.002-0.020%. In a gauged state, the steel is tempered at a temperature of 400-450°C, held for 4-6 hours and cooled in air. The resulting gauged product has enhanced strength and enhanced machining properties. |
