MANUFACTURE OF SURFACE HARDENED STEEL FOR RAPID HEATING AND QUENCHING

• Main Authors: TAKADA KATSUNORI, ISOGAWA KENJI
• Format: Patent
• Language: English
• Published: 23.03.1988
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

PURPOSE:To manufacture a surface hardened steel having desired surface hardness, a desired depth of the hardened layer and increased core strength by hot working a steel having a specified compsn. and by cooling it under controlled cooling conditions to form a bainite-base structure. CONSTITUTION:A steel having a compsn. consisting of, by weight, 0.30-0.70% C, 0.03-1.0% Si, 0.20-2.0% Mn and the balance essentially Fe or further contg. one or more among <=3.5% Ni, <=3% Cr, <=0.7% Mo, <=0.5% Nb, <=0.005% B, <=0.1% sol. Al and <=0.2% Ti is hot worked to a prescribed dimensions and cooled under controlled cooling conditions to form a structure contg. >=75vol% bainite. Thus, superior suitability to rapid heating and quenching is provided and surface hardening giving high surface hardness and a hardened layer to a sufficient depth is carried out. Thermal refining before rapid heating and quenching is made unnecessary.