PRODUCTION OF CASE HARDENING STEEL

• Main Author: HITOMI YASUO
• Format: Patent
• Language: English
• Published: 28.03.1990
• Subjects: CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVINGMATERIAL; METALLURGY; PERFORMING OPERATIONS; PUNCHING METAL; ROLLING OF METAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; TRANSPORTING

PURPOSE:To prevent the growth of crystalline grains at the time of carburizing heat treatment and to produce a high-quality case hardening steel by carrying out reheating rolling at a specific temp. twice or more in a product hot rolling stage and then exerting carburizing treatment. CONSTITUTION:In the hot rolling stage for steel product, reheating treatment is carried out at least twice or more at >=900 deg.C, by which Al and N in the steel are dispersedly precipitated finely and uniformly. Then, carburizing heat treatment is applied to the above steel. By this method, the problems of heat treatment strain and deterioration in mechanical properties can be obviated and the high-quality case hardening steel can be produced. This case hardening steel is applicable to gears, shafts, etc., used for civil engineering and construction machinery and industrial machinery.